CHAPTER VI

LEPIDOPTERA—OR BUTTERFLIES AND MOTHS

ORDER VI. LEPIDOPTERA.

_Wings four; body and wings covered with scales usually variegate in colour, and on the body frequently more or less like hair: nervures moderate in number, at the periphery of one wing not exceeding fifteen, but little irregular; cross-nervules not more than four, there being usually only one or two closed cells on each wing, occasionally none. Imago with mouth incapable of biting, usually forming a long coiled proboscis capable of protrusion. Metamorphosis great and abrupt; the wings developed inside the body; the larva with large or moderate head and strong mandibles. Pupa with the appendages usually adpressed and cemented to the body so that it presents a more or less even, horny exterior, occasionally varied by projections that are not the appendages and that may make the form very irregular: in many of the smaller forms the appendages are only imperfectly cemented to the body._

Lepidoptera, or butterflies and moths, are so far as ornament is concerned the highest of the Insect world. In respect of intelligence the Order is inferior to the Hymenoptera, in the mechanical adaptation of the parts of the body it is inferior to Coleoptera, and in perfection of metamorphosis it is second to Diptera. The mouth of Lepidoptera is quite peculiar; the proboscis—the part of the apparatus for the prehension of food—is anatomically very different from the proboscis of the other Insects that suck, and finds its nearest analogue in the extreme elongation of the maxillae of certain Coleoptera, e.g. _Nemognatha_. {305}The female has no gonapophyses, though in certain exceptional forms of Tineidae, there are modifications of structure connected with the terminal segments, that have as yet been only imperfectly investigated. As a rule, the egg is simply deposited on some living vegetable and fastened thereto. Lepidoptera are the most exclusively vegetarian of all the Orders of Insects; a certain number of their larvae prey on Insects that are themselves filled with vegetable juices (Coccidae, Aphidae) and a very small number (_Tinea_, etc.) eat animal matter. In general the nutriment appears to be drawn exclusively from the fluids of the vegetables, the solid matter passing from the alimentary canal in large quantity in the form of little pellets usually dry, and called frass. Hence the quantity of food ingested is large, and when the individuals unduly increase in number, forest trees over large areas are sometimes completely defoliated by the caterpillars.

[Illustration: Fig. 157.—Metamorphosis of a Lepidopteron (_Rhegmatophila alpina_, Notodontidae). (After Poujade, _Ann. Soc. ent. France_, 1891.) Europe. A, Egg; B, young larva, about to moult; C, adult larva; D, head and first body-segment of adult larva, magnified; E, pupa, × 2/1; F, male moth in repose; G, female moth in repose.]

Lepidoptera pass a larger portion of their lives in the pupal stage than most other Insects do; frequently during nine months of the year the Lepidopteron may be a pupa. In other Orders of {306}Insects it would appear that the tendency of the higher forms is to shorten the pupal period, and when much time has to be passed between the end of the feeding up of the larva and the appearance of the imago, to pass this time as much as possible in the form of a resting-larva, and as little as may be in the form of a pupa; in Lepidoptera the reverse is the case; the resting-larva period being usually reduced to a day or two. Hence we can understand the importance of a hard skin to the pupa. There are, however, numerous Lepidopterous pupae where the skin does not attain the condition of hardness that is secured for the higher forms by the chitinous exudation we have mentioned; and there are also cases where there is a prolonged resting-larva period: for instance _Galleria mellonella_ spins a cocoon in the autumn and remains in it as a resting larva all the winter, becoming a pupa only in the spring. In many of these cases the resting-larva is protected by a cocoon. It is probable that the chief advantage of the perfect chitinous exudation of the Lepidopterous pupa is to prevent the tiny, complex organisation from the effects of undue transpiration. Bataillon has suggested that the relation of the fluid contents of the pupa to air and moisture are of great importance in the physiology of metamorphosis.

The duration of life is very different in various forms of Lepidoptera. It is known that certain species (_Ephestia kuehniella_, _e.g._) may go through at least five generations a year. On the other hand, certain species that feed on wood or roots may take three years to complete their life-history; and it is probable that some of the forms of Hepialidae are even longer lived than this.

Lepidoptera have always been a favourite Order with entomologists, but no good list of the species has ever been made, and it would be a difficult matter to say how many species are at present known, but it can scarcely be less than 50,000. In Britain we have about 2000 species.

The close affinity of the Order with Trichoptera has long been recognised: Réaumur considered the latter to be practically Lepidoptera with aquatic habits, and Speyer pointed out the existence of very numerous points of similarity between the two. Brauer emphasised the existence of mandibles in the nymph of Trichoptera as an important distinction: the pupa {307}of _Micropteryx_ (Fig. 211) has however been recently shown to be similar to that of Trichoptera, so that unless it should be decided to transfer _Micropteryx_ to Trichoptera, and then define Lepidoptera and Trichoptera as distinguished by the condition of the pupa, it would appear to be very difficult to retain the two groups as distinct.

STRUCTURE OF IMAGO.—The head of a Lepidopteron is in large part made up of the compound eyes; in addition to these it frequently bears at the top a pair of small, simple eyes so much concealed by the scales as to cause us to wonder if seeing be carried on by them. The larger part of the front of the head is formed by the clypeus, which is separated by a well-marked line from the epicranium, the antennae being inserted on the latter near its point of junction with the former. There is sometimes (_Saturnia_, _Castnia_) on each side of the clypeus a deep pocket projecting into the head-cavity. The other parts of the head are but small. The occipital foramen is very large.[164]

[Illustration: Fig. 158—External structure of a female butterfly, _Anosia plexippus_. (After Scudder.) _a_, Base of antenna; _b_, pronotum; _b^2_, scutum of mesothorax; _c_, clypeus; _cx_, coxa; _d_, scutellum; _d^1_, scutellum of metathorax; _e_, post-scutellum (= base of phragma); _em_, epimeron; _ep_, episternum; _f_, scutum of metathorax; _m_, basal part of proboscis (= maxilla); _o_, eye; _p_, labial palp; _r_, mesosternum; _s_, prothoracic spiracle; _t_, tegula; _tr_, trochanter; 1-9, dorsal plates of abdomen.]

The antennae are always conspicuous, and are very various in form; they are composed of numerous segments, and in the males of many species attain a very complex structure, especially in Bombyces and Psychidae; they doubtless function in such cases as sense-organs for the discovery of the female.

The largest and most important of the mouth-parts are the maxillae and the labial palpi, the other parts being so small as to render their detection difficult. The labrum is a very short, {308}comparatively broad piece, visible on the front edge of the clypeus; its lateral part usually forms a prominence which has often been mistaken for a mandible; Kellogg has applied the term "pilifer" to this part. In the middle of the labrum a small angular or tongue-like projection is seen just over the middle of the base of the proboscis; this little piece is considered by several authorities to be an epipharynx.

[Illustration: Fig. 159—Mouth of Lepidoptera. Tiger-moth, _Arctia caja_. A, Seen from front; B, from front and below, _a_, Clypeus; _b_, labrum; _c_, epipharynx; _d_, mandibular area; _d′_, prominence beneath mandibular area; _e_, one side of haustellum or proboscis; _f_, maxillary palp; _g_, labial palp.]

MANDIBLES.—Savigny, Westwood, and others considered the parts of the labrum recently designated pilifers by Kellogg to be the rudimentary mandibles, but Walter has shown that this is not the case.[165] The mandibles are usually indistinguishable, though they, or some prominence possibly connected with them,[166] may frequently be detected in the neighbourhood of the pilifers; they are, according to Walter, largest and most perfectly developed in _Eriocephala_, a genus that was not distinguished by him from _Micropteryx_ and was therefore termed "niedere Micropteryginen," _i.e._ lower Micropteryges. The opinion entertained by Walter that _Micropteryx_ proper (his "höhere Micropteryginen") also possesses rudimentary mandibles is considered by Dr. Chapman, no doubt with reason, to be erroneous.[167] The mandibles, however, in the vast majority of Lepidoptera can scarcely be said to exist at all in the imago; there being only an obtuse projection—without trace of {309}articulation—on each side of the labrum; and even this projection is usually absent. Meinert recognised these projections as mandibles in _Smerinthus populi_, and Kellogg in _Protoparce carolina_, another large Sphinx moth. They appear to be unusually well developed in that group. In _Castnia_ they are even more definite than they are in Sphingidae.

The MAXILLAE are chiefly devoted to the formation of the proboscis. Their basal portions are anatomically very indefinite, though they exist very intimately connected with the labium. Each usually bears a small tubercle or a segmented process, the representative of the maxillary palpus. The proboscis itself consists of the terminal, or outer, parts of the two maxillae, which parts are closely and beautifully coadapted to form the spirally coiled organ, that is sometimes, though incorrectly, called the tongue. The exact morphology of the Lepidopterous proboscis has not been established. The condition existing in the curious family Prodoxidae (see p. 432), where a proboscis coexists with another structure called a maxillary tentacle, suggests a correspondence between the latter and the galea of a typical maxilla; and between the proboscis and the lacinia or inner lobe of a maxilla: but J. B. Smith is of opinion that the tentacle in question is a prolongation of the stipes. The condition of the parts in this anomalous family (Prodoxidae) has not, however, been thoroughly investigated, and Packard takes a different view of the proboscis; he considers that "it is the two galeae which become elongated, united and highly specialised to form the so-called tongue or glossa of all Lepidoptera above the Eriocephalidae."[168] The proboscis in some cases becomes very remarkable, and in certain Sphingidae is said to attain, when unrolled, a length of ten inches. In some cases the maxillary lobes do not form a proboscis, but exist as delicate structures, pendulous from the mouth, without coadaptation (_Zeuzera aesculi_, the Wood-leopard moth). In other forms they are absent altogether (_Cossus_, _e.g._), and in _Hepialus_ we have failed to detect any evidence of the existence of the maxillae. On the other hand, in _Micropteryx_ the maxillae are much more like those of a mandibulate Insect; and various other Microlepidoptera approach more or less a similar condition. In the genus last mentioned {310}the maxillary palpi are largely developed, flexible and slender. According to Walter various forms of palpus intermediate between that of _Micropteryx_ and the condition of rudimentary tubercle may be found amongst the Microlepidoptera.[169]

LABIUM.—The labial palpi are usually largely developed, though but little flexible; they form conspicuous processes densely covered with scales or hairs, and curve forwards or upwards, rarely downwards, from the under side of the head, somewhat in the fashion of tusks. The other parts of the labium are frequently represented merely by a membranous structure, united with the maxillae and obstructing the cavity of the pharynx. Where the proboscis is absent it is difficult to find any orifice leading to the alimentary canal, such opening as may exist being concealed by the overhanging clypeus and labium. In some forms, _Saturnia_, _e.g._, there appears to be no buccal orifice whatever. In _Hepialus_ the labium is in a very unusual condition; it projects externally in the position usually occupied by the labial palpi, these organs being themselves extremely short. It is very difficult to form an opinion as to the structure of the labium and other mouth-parts when the maxillae are not developed, as in these cases the parts are of a delicate membranous nature, and shrivel after death. This is the explanation of the fact that in descriptive works we find vague terms in use such as "mouth aborted" or "tongue absent."

The mouth of the Lepidopterous imago is a paradoxical structure; it differs very greatly from that of the larva, the changes during metamorphosis being extreme. We should thus be led to infer that it is of great importance to the creatures; but, on the other hand, the various structures that make up the mouth, as we have remarked, are frequently absent or reduced to insignificant proportions; and even in forms where the apparatus is highly developed the individuals seem to be able to accomplish oviposition without taking food, or after taking only very minute quantities. It is therefore difficult to understand why so great a change should occur during the metamorphosis of the Insects of this Order. It has been ascertained that in some forms where the mouth is atrophied the stomach is in a correlative condition; but we are not aware that any investigations have been made as to whether this correspondence is general or exceptional.

{311}The exact mode in which the proboscis acts is in several respects still obscure, the views of Burmeister and Newport being in some points erroneous. Towards the tip of the proboscis there are some minute but complex structures considered by Fritz Müller to be sense-organs, and by Breitenbach to be mechanical instruments for irritating or lacerating the delicate tissues of blossoms. It is probable that Müller's view will prove to be correct. Nevertheless the proboscis has considerable power of penetration; there being a moth, "_Ophideres fullonica_" that causes considerable damage to crops of oranges by inserting its trunk through the peel so as to suck the juices.[170] The canal formed by each maxilla opens into a cavity inside the front part of the head. This cavity, according to Burgess,[171] is a sort of sac connected with five muscles, and by the aid of this apparatus the act of suction is performed: the diverticulum of the alimentary canal, usually called a sucking-stomach, not really possessing the function formerly attributed to it.

The PROTHORAX is very small, being reduced to a collar, between the head and the alitrunk, of just sufficient size to bear the front pair of legs. Its most remarkable feature is a pair of processes, frequently existing on the upper surface, called "patagia." These in many cases (especially in Noctuidae) are lobes capable of considerable movement, being attached only by a narrow base. In _Hepialus_, on the contrary, they are not free, but are merely indicated by curved marks on the dorsum. The patagia are styled by many writers "tegulae." They are of some interest in connection with the question of wing-like appendages on the prothorax of Palaeozoic insects, and they have been considered by some writers[172] to be the equivalents of true wings. The Mesothorax is very large, especially its upper face, the notum, which is more or less convex, and in the higher forms attains a great extension from before backwards. The notum consists in greater part of a large anterior piece, the meso-scutum, and a {312}smaller part, the meso-scutellum behind. In front of the scutum there is a piece termed prae-scutum by Burgess. It is usually small and concealed by the front part of the scutum; but in _Hepialus_ it is large and horizontal in position. It is of importance as being the chief point of articulation with the prothorax. The scutellum is more or less irregularly rhomboidal in form; its hinder margin usually looks as if it were a lobe or fold placed in front of the base of the abdomen or metathorax, according to whether the latter is concealed or visible. In some of the higher forms this meso-scutellar lobe is prominent, and there may be seen under its projection a piece that has been called the post-scutellum, and is really the base of the great mesophragma, a chitinous piece that descends far down into the interior of the body. In addition to the front pair of wings the mesothorax bears on its upper surface another pair of appendages, the tegulae: in the higher forms they are of large size; they are fastened on the front of the mesothorax, and extend backwards over the joint of the wing with the body, being densely covered with scales so that they are but little conspicuous. These appendages are frequently erroneously called patagia, but have also been called scapulae, pterygodes, paraptera, and shoulder-tufts, or shoulder-lappets. The lower surface of the mesothorax is much concealed by the large and prominent coxae, but the sternum and the two pleural pieces on each side, episternum and epimeron, are easily detected. The area for attachment of the anterior wing on each side is considerable, and appears to be of rather complex structure; its anatomy has been, however, but little studied.

The METATHORAX is small in comparison with the preceding segment, to which it is intimately co-adapted, though the two are really connected only by delicate membrane, and can consequently be separated with ease by dissection. The metanotum consists of (1) the scutum, which usually appears externally as an anterior piece on each side; (2) the scutellum, forming a median piece placed behind the scutum, which it tends to separate into two parts by its own extension forwards. In order to understand the structure of the metathorax it is desirable to dissect it off from the larger anterior segment, and it will then be found that its appearance when undissected is deceptive, owing to its being greatly arched, or folded in the {313}antero-posterior direction. A broad, but short phragma descends from the hind margin of the metascutellum into the interior of the body. It should be noted that though the metanotum is forced, as it were, backwards by the great extension of the mesonotum in the middle line of the body, yet at the sides the metanotum creeps forward so as to keep the points of attachment of the hind wings near to those of the front wings. In many forms of Hesperiidae, Sphingidae, Noctuidae, etc. the true structure of the metanotum is further concealed by the back of the mesoscutellum reposing on, and covering it.

Difference of opinion exists as to the thoracic Spiracles; there is one conspicuous enough in the membrane behind the pronotum, and it is thought by some writers that no other exists. Westwood and Scudder, however, speak of a mesothoracic spiracle, and Dr. Chapman considers that one exists. Minot describes[173] a structure behind the anterior wing, and thinks it may be an imperfect spiracle, and we have found a similar stigma in _Saturnia pavonia_. At the back of the thorax there is on each side in some Lepidoptera (Noctuidae, _Arctia_, etc.), a curious large cavity formed by a projection backwards from the sides of the metasternum, and a corresponding development of the pleura of the first abdominal segment. Minot and others have suggested that this may be an organ of hearing.

The ABDOMEN differs according to the sex. In the female seven segments are conspicuous dorsally, but only six ventrally, because the first segment is entirely membranous beneath, and is concealed between the second abdominal ventral plate and the posterior coxae. Besides these segments there are at the hind end two others smaller, more or less completely withdrawn into the body, and in certain cases forming an ovipositor. These nine segments are usually considered to constitute the abdomen; but according to Peytoureau,[174] a tenth dorsal plate is represented on either side of the anal orifice, though there is no trace of a corresponding ventral plate. In the male the segments, externally conspicuous, are one more than in the female. According to the authority quoted,[175] this sex has also truly ten abdominal segments, the ninth segment being withdrawn to a greater or {314}less extent to the inside of the body, and modified to form part of a copulatory apparatus; its dorsal portion bears a process called the "uncus"; the anal orifice opens on the inner face of this process, and below it there is another process—developed to a greater or less extent—called the "scaphium." The ventral portion of the ninth segment bears a lobe, the "saccus" (Peytoureau, _l.c._). On each side of the ninth abdominal segment there is a process called the "valve," the internal wall of which bears some hook-like or other processes called "harpes"; it is continued as a membrane surrounding the "oedeagus," or penis, and—bearing more or less distinct prominences—connects with the scaphium. In many forms the parts alluded to, other than the valves, are concealed by the latter, which come together when closed, and may be covered externally with scales like the rest of the abdomen. Peytoureau considers that the uncus is really the dorsal plate of a tenth segment, and that the scaphium is the tenth ventral plate. Thus, according to this view, the ninth segment is extensive and complex, being very highly modified in all its parts: while the tenth segment is greatly reduced. The structure of the male organs is simpler in Lepidoptera, and less varied than it is in the other great Orders of Insects. There are seven pairs of abdominal spiracles on the upper parts of the membranous pleurae.

[Illustration: Fig. 160—_Acherontia atropos._ The termination of ♂ body, one side removed. _IX_, Ninth dorsal plate; _IX’_, ninth ventral; _s_, lobe, saccus, of ninth ventral plate; _X_, tenth dorsal plate, or uncus; _sc_, scaphium, or tenth ventral plate; _a_, position of anus; _b_, chitinised band of scaphium; _V_, valve or clasper; _c_, hooks, or harpes, of clasper; _p_, penis (or oedeagus). (After Peytoureau.)]

LEGS.—The legs are long, slender, covered with scales, and chiefly remarkable from the fact that the tibiae sometimes bear articulated spurs on their middle as well as at the tip. The front tibia usually possesses on its inner aspect a peculiar mobile pad; this seems to be in some cases a combing organ; it also often acts as a cover to peculiar scales. The tarsi are five-jointed, with two small claws and a small apparatus, {315}the functional importance of which is unknown, between the claws.

WINGS.—The wings are the most remarkable feature of this Order; it is to them that butterflies owe their beauty, the surfaces of the wings being frequently adorned with colours and patterns of the most charming and effective nature. These effects are due to minute scales that are implanted in the wing-membrane in an overlapping manner, somewhat similar to the arrangement of slates on the roof of a house. The scales are very readily displaced, and have the appearance of a silky dust. We shall describe their structure and allude to their development subsequently. The wings are usually of large size in comparison with the Insect's body: in the genus _Morpho_, the most gorgeous of the butterflies, they are enormous, though the body is small; so that when deprived of these floats the Insect is insignificant. The great expanse of wing is not correlative with great powers of flight, though it is perhaps indicative of flying with little exertion; for the small-winged Lepidoptera, Sphingidae, etc., have much greater powers of aërial evolution than the large-winged forms. The area of the wing is increased somewhat by the fact that the scales on the outer margin, and on a part or on the whole of the inner margin, project beyond the edges of the membrane that bears them: these projecting marginal scales are called fringes. In many of the very small moths the actual size of the wing-membranes is much reduced, but in such cases the fringes may be very long, so as to form the larger part of the surface, especially of that of the hind wings. Frequently the hind wings are of remarkable shape, being prolonged into processes or tails, some of which are almost as remarkable as those of _Nemoptera_ in the Order Neuroptera.

The wings are very rarely absent in Lepidoptera; this occurs only in the female sex, no male Lepidopterous imago destitute of wings having been discovered. Although but little is known of the physiology of flight of Lepidoptera, yet it is clearly important that the two wings of the same side should be perfectly coadapted or correlated. This is effected largely by the front wing overlapping the hind one to a considerable extent, and by the two contiguous surfaces being pressed, as it were, together. This is the system found in butterflies and in some of the large moths, such as Lasiocampidae and Saturniidae; in these cases the hind {316}wing always has a large shoulder, or area, anterior to its point of insertion. In most moths this shoulder is absent, but in its place there are one or more stiff bristles projecting forwards and outwards, and passing under a little membranous flap, or a tuft of thick scales on the under face of the front wing; the bristle is called the "frenulum," the structure that retains it a "retinaculum." In _Castnia_ (Fig. 162) and in some Sphingidae there is the unusual condition of a highly-developed shoulder (_s_) coexisting with a perfect frenulum (_f_) and retinaculum (_r_). The frenulum and retinaculum usually differ in structure, and the retinaculum in position, in the two sexes of the same moth; the male, which in moths has superior powers of flight, having the better retaining organs. Hampson says "the form of the frenulum is of great use in determining sex, as in the males of all the forms that possess it, it consists of hairs firmly soldered together so as to form a single bristle, whilst in nearly all females it consists of three or more bristles which are shorter than that of the male; in one female Cossid I have found as many as nine. Also in the large majority of moths the retinaculum descends from the costal nervure in the male, while in the female it ascends from the median nervure."[176] This sexual difference in a structure for the discharge of a function common to the two sexes is a very remarkable fact. There are a few—very few—moths in which the bases of the hind wings are not well coadapted with the front wings, and do not possess a frenulum, and these species possess a small more or less free lobe at the base of the front wing that droops towards the hind wing, and may thus help to keep up an imperfect connexion between the pair; this lobe has been named a jugum by Professor Comstock. Occasionally there is a jugum on the hind as well as on the front wing. There is usually a very great difference between the front and the hind wings; for whereas in the front wing the anterior portion is doubtless of great importance in the act of flight and is provided with numerous veins, in the hind wing, on the other hand, the corresponding part has not a similar function, being covered by the front wing; hence the hind wing is provided with fewer nervures in the anterior region, the divisions of the subcostal being less numerous than they are in the front wing. In the moths possessing a jugum the two wings differ but little from one {317}another, and it is probable that they function almost as four separate wings instead of as two pairs.

WING-NERVURES.—The nervures or ribs of the wings are of great importance in Lepidoptera, as at present they furnish the chief characters for classification and for the discussions of phylogeny that are so numerous in entomological literature. On looking at wings that have been deprived of their scales it will be noticed (Fig. 161) that the ribs are much more numerous at the outer margins than they are near the points of attachment of the wings, and that there is usually but one cell (or area completely enclosed by ribs). This latter point is one of the chief peculiarities of the Lepidopterous wing; in Insect-wings generally the number of cells in proportion to the area of the wings and to the number of nervures is greater than it is in Lepidoptera, for in the latter there are few or no cross-nervures. Hence there is sometimes no closed cell at all on the wing (Fig. 161, II. B). The maximum number of closed cells is six; this is found in some species of _Micropteryx_, while in _Hepialus_ there may be three or four; but the rule is that there is only one cell in the Lepidopterous wing. When the number of cells is increased this is not necessarily due to an increase in the cross-nervures; and in fact it is generally due to irregular forking or to the sinuous form of the longitudinal nervures themselves (see wing of _Castnia_, Fig. 162, A.). Some authorities consider that all transverse or cross-veins in Lepidoptera are merely portions of longitudinal veins having diverted courses. When a portion of a nervure beyond the basal or primary portion serves as a common piece to two forked parts external to it, it is called a stalk (Fig. 162, A, _e_). There are cases in which the furcation takes place in the opposite direction, so that a nervure is double at the base of the wing (Fig. 161, I, A, 1_a_, and B, 1_b_). This important condition has not yet been adequately discussed.

{318}[Illustration: Fig. 161.—Wing-nervuration of Lepidoptera. I, Diagram of moths' wings (after Hampson); II, of a butterfly's wings (_Morpho menelaus_ ♂, after Staudinger and Schatz). A, front, B, hind wing. I.—_c_, costal; _sc_, subcostal; _m_, median; 1_a_, 1_b_, 1_c_, internal nervures; _f_, frenulum; 2, 3, 4, branches of median nervure; 5, lower radial; 6, upper radial; 7-11, divisions of the subcostal; 12, termination of costal; _c_, cell; _d_, discocellular nervure. II.—C, costal; SC, subcostal; M, median; SM and SN, submedian nervures; 1A, inner-margin nervure; UR, lower radial; OR, upper radial; SC^1 to SC^5, divisions of subcostal; M^1 to M^3, divisions of median nervure; C, cell; DC, discocellulars.]

Turning to the mode of designation of the nervures,[177] we may commence by remarking that no system satisfactory from a practical as well as from a theoretical point of view has yet been devised. The diagrams given in figure 161 will enable us to explain the methods actually in vogue; I. representing the system, dating from the time of Herrich-Schaeffer, chiefly used by British naturalists, and II. that adopted by Staudinger and Schatz in their recent great work on the Butterflies of the world. The three anterior nervures in both front and hind wings correspond fairly well, and are called, looking at them where they commence at the base of the wing, "costal," "subcostal," and "median" nervures. The nervures near the inner margin of the wing (that is the lower part in our figures) differ much in the front and hind wings, consisting either of two or of three separate portions not joined even at the base. British entomologists call these "branches or divisions of the internal nervure": the Germans call the more anterior of them the "submedian," and the more internal the "inner-margin nervure"; they are also frequently called anal nervures. The cross-nervure that closes the cell is called discocellular; when apparently composed of two or three {319}parts joined so as to form angles, the parts are called, according to position, upper, lower, and middle discocellulars. One or more short spurs may exist on the front part of the basal portion of the hind wing; these are called praecostal. The branches or terminal divisions of the nervures should be called nervules; they are usually mentioned by the numbers shewn in the diagram (Fig. 161, I.). In addition to this, it is only necessary to remember that number 2 is always assigned to the posterior division of the median nervure, the nervules below this being all called 1, and distinguished by the addition of _a_, _b_, _c_ when requisite. This course is necessary, because if it were not adopted the corresponding nervules on the front and hind wings would bear different numbers.

The use of this system of numbers for the nervules is becoming general, and it answers fairly well for practical purposes. On the other hand, extreme discrepancy exists as to the nomenclature of the nervures and nervules, and there are almost as many systems as there are authorities.

The normal number of nervules is, on the front wing, 11 + 1 or 2 inner marginal, and on the hind wing 7 + 2 or 3 inner marginal. In the aberrant moths of the genus _Castnia_ the nervuration is unusually complex and irregular (Fig. 162), and an analogous condition occurs in our common Goat-moth (_Cossus ligniperda_). In _Hepialus_ and _Micropteryx_ (the jugate moths of Comstock) the hind wings are less dissimilar in nervuration from the front wings than they are in other Lepidoptera.[178]

[Illustration: Fig. 162—Wing-nervuration of _Castnia_. Undersides of, A, front, B, hind wings. 1_a_, 1_b_, 1_c_, 1_d_, Inner marginal nervures; 2, lower branch of median; 8, subcostal of hind wing; 12, subcostal of front wing; _e_, "stalk" of 8 and 9; _f_, frenulum; _r_, retinaculum; _s_, shoulder; _g_, articulation of wing.]

INTERNAL ANATOMY.[179]—The alimentary canal extends as a long, {320}slender oesophagus through the length of the thorax, dilating when it reaches the abdomen to form a tubular stomach; before this it is somewhat enlarged to form an indistinct crop, and gives off a large diverticulum usually called a sucking stomach. According to Burgess, this structure does not possess the function ascribed to it by this name, and he terms it a food-reservoir. The Malpighian tubes are six in number, three on each side, and each set of three unite to form a common tube opening into the posterior extremity of the stomach; behind them the alimentary canal continues in the form of a slender, tortuous intestine, expanding at the extremity of the body to form a rectum. The dorsal or circulatory vessel commences near the posterior extremity of the body, but in the front part of the abdomen is deflexed to pass under the great phragma into the thorax, where it rises abruptly to the dorsal wall, but is again abruptly deflexed, forming a loop, and is then prolonged above the oesophagus into the head: at the summit of the thoracic loop there may be a dilatation called the aortal chamber. The supra- and infra-oesophageal ganglia are consolidated into a mass pierced by the oesophagus: there is a minute frontal ganglion; the ventral chain consists of three much approximated thoracic ganglia and four abdominal ganglia separated from the thoracic by a long interval.

[Illustration: Fig. 163—Internal anatomy of Lepidoptera. Section of the body of a female butterfly, _Anosia plexippus_. (After Scudder.) The portion to the left of the vertical line more magnified. I. II. III. thoracic segments; 1-9, abdominal segments; _a_, antenna; _a_, anus; _ac_, aortal chamber; _ag^1_, etc., abdominal ganglia; _agl^1_, _agl^2_, accessory glands; _ao_, aorta; _br_, brain; _c_, colon; _cp_, copulatory pouch; _cx^1_, _cx^2_, _cx^3_, coxae; _fr_, food-reservoir; _g^1_, suboesophageal ganglion; _h_, dorsal vessel; _i_, intestine; _lm_, area filled by wing muscles; _l.or_, ovary, or egg-tubes of left side; _mv_, Malpighian tube (the two others of the right side cut away, except small portions); _mx_, maxilla; _o_, oviduct; _oo_, its orifice; _oe_, oesophagus; _ov.c_, end of left ovary; _p_, labial palp; _ph_, pharynx; _r.ov_, terminal parts of right ovarian tubes, turned to one side, after the tubes have been cut away; _sd_, salivary duct; _sgl_, salivary gland; _sp_, spermatheca; _st_, stomach; _tg_, thoracic ganglia; _v_, copulatory orifice.]

{321}The male sexual organs consist of the two testes placed in a common capsule, from which proceed a pair of contiguous vasa deferentia (dilated soon after their origin to form the vesiculae seminales); into each vas there opens a long, tubular gland; the two vasa subsequently unite to form a long, coiled, ejaculatory duct. It is in the structure of the female sexual organs that the most remarkable of the anatomical characters of Lepidoptera is found, there being two external sexual orifices. The imago has, in the great majority of cases, four egg-tubes in each ovary; the pair of oviducts proceeding from them unite to form a single unpaired (azygos) oviduct which terminates by an orifice quite at the posterior extremity of the body. There is a sac, the bursa copulatrix or copulatory pouch, which is prolonged in a tubular manner, to open externally on the eighth ventral plate: a tube, the seminal duct, connects the bursa with the oviduct, and on this tube there may be a dilatation—the spermatheca. Besides these structures two sets of accessory glands open into the oviduct, an unpaired gland, and a pair of glands. The development of these structures has been described by Hatchett Jackson,[180] and exhibits some very interesting features. The exact functions of the bursa copulatrix and of the other structures are by no means clear. According to Riley,[181] the spermatheca in _Pronuba_ contains some curious radiate bodies, and Godman and Salvin describe something of the same sort as existing in butterflies. Several variations in the details of the structure of these remarkably complex passages have been described, and the various ducts are sometimes rendered more complex by diverticula attached to them. Some noteworthy diversities in the main anatomical features exist. According to Cholodkovsky, there is but one sexual aperture—the posterior one—in _Nematois metallicus_; while, according to Brandt, the number of egg-tubes in a few cases exceeds the normal—four—being in _Sesia scoliaeformis_ fourteen. In _Nematois metallicus_ there is individual variation, the number of tubes varying from twelve to twenty.

The EGG has been more extensively studied in Lepidoptera than in any other Order of Insects. It displays great variety: we meet with elongate forms (Fig. 164) and flat forms like buttons, while in _Limacodes_ (Fig. 83, Vol. V.) the egg is a {322}transparent scale of somewhat inconstant outline. Some are coloured and mottled somewhat after the fashion of birds'-eggs; this is the case with some eggs of Lasiocampidae and Liparidae; in some the sculpture of the egg-shell is of the most elaborate character (Figs. 77, 78, Vol. V.). The egg-shell or chorion is, according to Korschelt[182] and others, a cuticular product of the epithelium of the egg-chambers of the ovaries. The number of eggs deposited by an individual differs greatly in different species, and has been ascertained to be variable within certain limits in the same species. Speyer thought about 250 to be the average number of eggs deposited by an individual. The number in the case of _Aporia crataegi_ is believed to be from 60 to 100, and in some _Hepialus_ to be several thousands. The mode of deposition also differs greatly; where the eggs are very numerous they seem to be discharged almost at random in suitable spots; but moths such as _Clisiocampa neustria_ fasten their eggs round the stems of the food-plant in a very perfect and artistic manner. Butterflies seem as a rule to prefer to oviposit by placing an egg here and there rather than risk many in one situation; but to this there are many conspicuous exceptions especially in the cases where the larvae live gregariously, as in the Vanessae. Some moths cover the eggs with fur from their own body, which, in the case of certain of the Eggers (Lasiocampidae), seems to have a special supply for the purpose. The period that intervenes between deposition and hatching of the eggs varies from a few days to many months. There seems to be, as a rule, comparatively little power of extending the period of latency beyond a single season; though certain facts have been recorded that would lead us to believe that in Australia eggs may last over the proper time during a drought, and be hatched as soon as rain falls.

[Illustration: Fig. 164—Egg of Orange-tip butterfly, _Euchloe cardamines_, magnified. _a_, The egg of natural size on a stalk.]

LARVA.—The young condition or larva of the Lepidopterous Insect is commonly called a caterpillar. It is a somewhat worm-like creature—in old English it was sometimes called {323}palmer-worm—and is composed of a head and thirteen divisions or segments of the body; the first three of the latter are called thoracic, the other ten, abdominal segments; in most caterpillars the terminal two or three abdominal segments are more or less run together, and the ninth may be very small, so that the true number is indistinct. The first three segments bear each, on either side, a short limb, ending in a curved spine; the next two (or three or more) segments are destitute of legs, but on some of the following divisions another kind of leg of a more fleshy character appears, while the body is terminated by a pair of these thick legs of somewhat different form. The front legs are usually called the true legs, the others prolegs, but this latter designation is a most unfortunate one, the term "pro" being in entomology used to signify anterior; it is therefore better to call the three anterior pairs thoracic legs, and the others abdominal feet, distinguishing the hind pair of these latter as claspers. There is, too, an unfortunate discrepancy amongst entomologists in their manner of counting the body-segments, some count the head as the first segment, while others apply this term to the first thoracic segment. The latter is the more correct course, for, as the head is not a single segment it should not be called such in a terminology that affects to be morphologically exact, not simply descriptive. The thoracic legs are transversely jointed (Fig. 165, B), but this is not the case with the abdominal feet, which are usually armed beneath with a circle, or with rows, of little hooks. The thoracic legs are, independent of their form, of a different nature from the abdominal, for these latter disappear subsequently, while the former give rise to the legs of the imago. The number of thoracic legs is always six, except in a few cases where there are none at all; the abdominal feet are much more variable, and exhibit so many distinctions that we cannot here attempt to deal with them. M. Goossens has given a concise and interesting account of this subject,[183] and Speyer[184] a summary of the variety in number and position.

The anatomy of the larva is simple in comparison with that of the perfect Insect; its main features will be appreciated from Fig. 165, from which it will be seen that the stomach is enormous, and the silk-vessels are also very extensive.

{324}[Illustration: Fig. 165.—A, Section of male caterpillar of _Anosia plexippus_—muscular and tracheal systems and fat-body not shown: I, pro-, II, meso-, III, meta-thorax; 1-10, abdominal segments; _b_, supra-oesophageal ganglion; _c_, rectum; _d.v_, dorsal vessel; _g^3-g^9_, ganglia of ventral chain; _h_, head; _i_, intestine; _m.v_, Malpighian tube; _n.c_, nerve-cord of ventral chain; _oe_, oesophagus; _s_, spinneret; _s.o.g_, infra-oesophageal ganglion; _st_, stomach; _s.v_, silk-vessel; _t_, testis. B, One of the jointed prothoracic legs. C, An abdominal foot with its hooks. (After Scudder and Burgess, magnification about 2/1.)]

There are three sets of glands opening by canals on the head, viz. the salivary glands proper, which open into the cavity of the mouth, one close to the base of each mandible; the silk-glands, which terminate by a common canal, continued externally as the spinneret; and the glands of Filippi situate in the head itself, and opening into the ducts of the silk-glands, near their union into a common duct. It should be recollected that Fig. 165 does not indicate all the details of the anatomy; the muscular system, for instance, being entirely omitted, though there are an enormous number of muscles; these however are not very complex, they being mostly repetitions in the successive segments.[185] The mouth-parts are very different from those of the perfect Insect, inasmuch as the maxillae and labial palpi, which are the most remarkable structures of the imago, are small, and are differently constructed in the caterpillar, while the mandibles, which are the largest organs of the caterpillar, disappear in the adult. The little organ by which the caterpillar exudes its silk is called a spinneret; according to Packard it is a "homologue of the hypopharynx." It is a more or less prominent point on the middle of the labium (Fig. 166, _g_) and sometimes forms a conspicuous spine projecting downwards. The eyes are extremely imperfect organs, consisting merely of six, in some cases {325}fewer, transparent, somewhat prominent, little spaces placed on each side of the lower part of the head; they are called "ocelli," by Landois "ocelli compositi." Under each of these external facets there are placed percipient structures, apparently very imperfect functionally, the caterpillar's sight being of the poorest character.[186] The spiracles of the caterpillar are nine on each side, placed one on the first thoracic segment and one on each of the first eight abdominal segments; there are no true stigmata on the second and third thoracic segments, though traces of their rudiments or vestiges are sometimes visible.

[Illustration: Fig. 166—Front view of head of a caterpillar, with the jaws

## partially opened, _a_, Labrum; _b_, mandible; _c_, antenna; _d_, ocelli;

_e_, maxilla; _f_, lingua; _g_, spinneret; _h_, labial palp.]

In the caterpillar there are no traces of the external sexual organs, so that the two sexes cannot be distinguished on superficial inspection; it was however long ago demonstrated by Herold[187] that the ovaries and testes exist in the youngest caterpillars, and undergo a certain amount of growth and development in the larval instars; the most important feature of which is that the testes are originally separate but subsequently coalesce in the middle line of the body, and become enclosed in a common capsule. In a few forms—especially of Liparidae—(Lymantriidae of modern authors)—the caterpillars are said to be of different colours in the two sexes. Most of what is known on this point has been referred to by Hatchett Jackson.[188]

The Silk-glands of Lepidoptera are of great interest from the physiological point of view, as well as from the fact that they have furnished for many ages one of the most beautiful of the adornments made use of by our own species. The sericteria, or vessels that secrete silk, are of simple structure, and differ greatly in their size in the various forms of the Order; they sometimes become of great length; in the Silk-worm each of the two vessels is nearly five times as long as the body, while in _Bombyx yamamai_ and others, even this is exceeded. They {326}grow with remarkable rapidity, being in the young silk-worm only 3 mm. long, in the adult 22 mm. The increase in weight is still more remarkable; when the silk-worm is thirty-one days old, the sericteria weigh only 3 mgr., but when the age is fifty days their weight has increased to 541 mgr., being then ⅖ of the whole weight of the body. In the pupa they undergo a gradual atrophy, and in the moth they are, according to Helm, no longer to be found, though earlier authors were of a contrary opinion.[189] According to Joseph,[190] the silk-vessels begin to develop at an extremely early age of the embryo, and are very different in their nature from the salivary glands, the former being derivatives of the external integument (ectoderm), while the salivary glands belong to the alimentary system. This view is to some extent confirmed by the observations of Gilson as to the different manner in which these two sets of glands discharge their functions.

The chief feature in the anatomy of the larva is the great size of the stomach. There is a very short oesophagus and crop; the latter becomes enlarged, spreading out so as to form the stomach, a great sac occupying the larger part of the body-cavity (Fig. 165). On the hinder end of this sac the Malpighian tubes open; they are similar in their disposition to those of the imago; behind the stomach the canal expands into two successive, short dilatations, the first called an intestine, the second a rectum; they are connected by very short isthmuses. The dorsal vessel is a simple, slender tube, extending from the eighth abdominal segment to the head. The main nervous system consists of supra- and infra-oesophageal ganglia, a small frontal ganglion, and a ventral chain of eleven ganglia, three thoracic and eight abdominal, the last of these latter being double. The sexual organs are quite rudimentary, and the passages connected with them very incompletely developed.

PUPA.—The pupa, which is one of the most remarkable of the instars of an Insect's life, attains its highest development in Lepidoptera. The Lepidopterous pupa is frequently called a "chrysalis," a term originally applied to certain metallic butterfly pupae. The Lepidopterous pupa differs from that of other Insects in the fact that its outer skin forms a hard shell, all the appendages of {327}the body being glued together by an exudation so as to form a single continuous outer skin. This form of perfect pupa is called "pupa obtecta." The obtected pupa is exhibited in various stages of perfection in the Lepidoptera; the maximum of perfection is attained by the pupae of such butterflies as are exposed without protection or concealment; on the other hand, we find in various small moths conditions of the pupa that do not differ in any marked manner from the pupae of Insects of other Orders. Moreover, certain Coleoptera and Diptera exhibit obtected pupae of a more or less perfect kind. Hence the pupa obtecta is to be considered as a perfected condition that exists more frequently in the Lepidoptera than in other Orders.

[Illustration: Fig. 167.—Section of female pupa of _Anosia plexippus_, 3-4 days old. I, pro-, II, meso-, III, meta-thorax; 1-9, abdominal segments; _a_, antenna(?); _ac_, aortal chamber; _ag^1-ag^5_, abdominal ganglia; _agl_, accessory glands; _ao_, aorta; _br_, brain; _c_, colon; _cp_, bursa copulatrix; _cr_, cremaster; _f^1_, first femur; _fr_, food-reservoir; _h_, dorsal vessel; _i_, part of intestine; _mv_, Malpighian tube; _mx_, base of maxilla; _oe_, oesophagus; _ov_, ovary; _ph_, pharynx; _sd_, salivary duct; _sgl_, salivary gland; _st_, stomach; _t^1_ first tarsus; _tg_, compound thoracic ganglion; _ts^2_, _ts^3_, second and third tarsus. (After Scudder.)]

The pupa has no orifices to the alimentary canal or sexual organs, but the respiratory openings are pervious. It has no means of locomotion, but it can move a certain number of the posterior segments (the number variable according to kind). In some cases it is provided with spines, "adminicula," by means of which, aided by the wriggling movements of the abdominal segments, considerable changes of position can be effected. The pupae of the genus _Micropteryx_ apparently use the legs for locomotion, as do the pupae of Trichoptera.

The study of the pupa of Lepidoptera is less advanced than that of the imago and larva, between which it is, in many points of structure, intermediate.[191] The interior of the pupa contains a {328}quantity of cream-like matter, including the results of histolysis—but this, as well as the condition of the internal organs, differs much according to whether the change from the caterpillar to the moth is much or little advanced.

Many pupae are protected by cocoons. These are masses of silk—very various in form—disposed by the caterpillar around itself during the last stage of its existence. Some of these cocoons are so perfect that the moth has considerable difficulty in escaping when the metamorphosis is complete. Various devices are used for the purpose of emergence; the Puss-moth excretes a corrosive fluid, containing potassium hydroxide, and then protects itself from this by retaining on the head while passing through it a shield formed of a portion of the pupa-skin.[192] Lepidopterous pupae usually have the body terminated by a projection of very various and peculiar form called "cremaster." In certain cases these projections are used for the suspension of the pupa, and are then frequently provided with hooks (Fig. 177, C, D). In other cases the cremaster is frequently called the anal armature (Fig. 205, B).

[Illustration: Fig. 168—Wing-rudiments of _Pieris brassicae_. A, Rudiments of a wing before the first moult of the caterpillar: _ce_, embryonic cells; _ch_, external cuticle; _h_, hypodermis; _o_, opening of the invagination; _tr_, trachea. B, posterior wing-rudiment of full-grown caterpillar; _b_, semicircular pad; _c_, a bundle of the rolled tracheae; _e_, envelope; _i_, pedicel; _tr_, trachea. (After Gonin.)]

The DEVELOPMENT of the WINGS of Lepidoptera has recently been much studied. It has been known since the time of Lyonnet, that the rudiments of the wings exist inside the body of the caterpillar when it is nearly adult. Verson considers that he has detected the rudiments in the silk-worm larva even before hatching, and he attributes their origin to a modification of form of those hypodermal cells that occupy the spots where the spiracles of the second and third thoracic segments might be looked for. (It will be recollected that there are no spiracles on these two thoracic segments in Lepidopterous larvae). Gonin has examined the wing-rudiments in the caterpillar, a few days old, of {329}_Pieris brassicae_,[193] and finds that the future wing is then indicated by a thickening and bagging inwards of the hypodermis, and by some embryonic cells and a trachea in close relation with this mass (Fig. 168, A). The structure grows so as to form a sac projecting to the interior of the body, connected with the body-wall by a pedicel, and penetrated by a trachea forming branches consisting of rolled and contorted small tracheae (Fig. 168, B). If the body-wall be dissected off the caterpillar immediately before pupation the wings appear in crumpled form, as shown in Fig. 169. This fact was known to the older entomologists, and gave rise to the idea that the butterfly could be detected in a caterpillar by merely stripping off the integument.

The exact mode by which the wings become external at the time of appearance of the chrysalis is not ascertained; but it would appear from Gonin's observations that it is not by a process of evagination, but by destruction of the hypodermis lying outside the wing. However this may be, it is well known that, when the caterpillar's skin is finally shed and the chrysalis appears, the wings are free, external appendages, and soon become fastened down to the body by an exudation that hardens so as to form the shell of the chrysalis.

[Illustration: Fig. 169—Anterior parts of a caterpillar of _P. brassicae_, the body-wall having been dissected off, immediately before pupation. _a_, _a′_, Anterior and posterior wings; _st I_, first spiracle; _p_, _p′_, second and third legs. (After Gonin.)]

SCALES AND NERVURES.—Before tracing the further development it will be well to discuss the structure of the scales and nervures that form such important features in the Lepidopterous wing.

If a section be made of the perfect wing of a Lepidopteron, it is found that the two layers or walls of the wing are firmly held together by material irregularly arranged, in a somewhat columnar manner. The thickness of the wing is much greater where the section cuts through a nervure (Fig. 170, A). The nervures apparently differ as to the structures found in them. Spuler observed in a nervure of _Triphaena pronuba_, a body having in section a considerable diameter, that he considered to be a {330}trachea, and also a "wing-rib" and blood-cells. He remarks that even in nervures, perfectly formed as to their chitinous parts, either wing-rib or trachea or both may be absent.[194] Schäffer[195] was unable to find any tracheae in the completed wings he examined, and he states that the matrix of the tracheae and even their inner linings disappear. The wing-ribs were, however, found by him to be present (Fig. 170, A and B).

[Illustration: Fig. 170.—Structure of wing of imago. A, Transverse section of basal portion of wing [of _Vanessa_?] containing a nervure; _c_, cuticle; _fr_, wing-rib; _g_, wall of nervure ("Grundmembran"); _h_, hypodermis; _p_, connecting columns: _r_, lumen of nervure; B, section of a rib; _b_, one of the chitinous projections; _str_, central rod. (After Schäffer.)]

[Illustration: Fig. 171—Scales of male _Lepidoptera_. A, Scale from upper surface of _Everes comyntas_; B, from upper surface of _Pieris rapae_; C, from inner side of fold of inner margin of hind wing of _Laertias philenor_; D, one of the cover-scales from the costal androconium of _Eudamus proteus_; E, F, G, scales from androconium of _Thorybes pylades_. (After Scudder).]

The scales that form so conspicuous a feature in Lepidoptera exist in surprising profusion, and are of the most varied forms. They may be briefly described as delicate, chitinous bags; in the completed state these bags are flattened, so as to bring the sides quite, or very nearly, together. Their colour is due to contained pigments, or to striation of the exposed surface of the scale; the latter condition {331}giving rise to metallic "interference-colours." The walls of the scales are themselves, in some cases, tinted with pigment. It is said that some of the scales contain air, and that the glistening whiteness of certain scales is due to this. The exposed surface of the scale usually differs from the surface that is pressed down on the wing in being delicately and regularly striated; the colours of the upper and under surfaces of a scale may also be quite different. Scales are essentially of the nature of hairs, and all the transitions between hairs and true scales may be found on the wings of certain Lepidoptera that bear both hairs and scales, e.g. _Ithomia_. It has been calculated that there are a million and a half of scales on the wings of an individual of the genus _Morpho_. The scales are arranged on the wing in an overlapping manner, somewhat like slates on the roof of a house. Each scale has a short stalk, and is maintained in position by the stalk fitting into a cavity in a projection of the wing-membrane (Fig. 172).

[Illustration: Fig. 172—Insertion of scales. A, Socket holding the stalk in _Galleria mellonella_; B, insertion of the scale of _Polyommatus phloeas_. _b_, Base of scale; _r_, holding-ring; _w_, surface of wing. (After Spuler.)]

ANDROCONIA.—The males of numerous butterflies possess scales peculiar in kind and various in arrangement. They may be either irregularly scattered over the wing, or they may form very complex definite structures (Fig. 173). They were formerly called "plumules," but Scudder has replaced this name by the better one, "androconia." The function of the androconia is still obscure. An odour is believed to be connected with them. Thomas supposes[196] that these scales are hollow tubes in connection with glands at their bases, and that matter secreted by the glands passes through the scales and becomes diffused. In nearly all Lepidoptera it is the male that seeks the female; if therefore odorous scales were present in one sex only we should have supposed that this would have been the female rather than the male. As, however, the reverse is the case, the function of the androconia is supposed to be that of charming the female. Scudder considers that the covering part of the androconial {332}structures is sometimes ornamental. As a rule, however, the "brands" of male Lepidoptera detract from their beauty to our eyes.

[Illustration: Fig. 173—A, section of part of wing showing the complex androconia of _Thanaos tages_, a Skipper butterfly. The turning over of the costal margin of the wing is in this case part of the arrangement. _a_, Upper covering-scales attached to the costal portion of the under surface of the wing; _b_, edge of costal margin of the wing; _c_, costal nervure with its scales; _d_, field of the wing next the costal nervure, bearing stunted scales; _e_, the androconia proper, or male scales; _f_, posterior covering scales; _g_, lumen of the costal nervure: B, a portion of the costal area flattened out and seen from above; lettering as before: C, section of androconium on the second nervure of _Argynnis paphia_. (After Aurivillius.)]

Resuming our consideration of the DEVELOPMENT of the WINGS, we may remark that the history of the changes during the pupal state is still imperfect. By the changes of relative size of the thoracic segments the hind wing is brought to lie under the anterior one (_i.e._ between it and the body), so that in the newly formed pupa the arrangement is that shown in Fig. 174. The wings are two sacs filled with material surrounding peritracheal spaces in which run tracheae. The subsequent history of the tracheae is very obscure, and contrary opinions have been expressed as to their growth and disappearance. We have alluded to the fact that in some nervures tracheae are present, while in others they are absent; so that it is quite possible that {333}the histories of the formation of the nervures and of their relation to tracheae are different in various Lepidoptera. This conclusion is rendered more probable by the statement of Comstock and Needham,[197] that in some Insects the "peritracheal spaces" that mark out the position of the future nervures are destitute of tracheae. Gonin thinks the nervures are derived from the sheaths of the peritracheal spaces, and a review of all the facts suggests that the tracheae have only a secondary relation to the nervures, and that the view that a study of the pupal tracheae may be looked on as a study of the preliminary state of the nervures is not sufficiently exact. It is, however, probable that in Lepidoptera the pupal tracheae play an important though not a primary part in the formation of the nervures; possibly this may be by setting up changes in the cells near them by means of the air they supply. Semper long ago discovered hypodermal cylinders traversed by a string (Fig. 170, B), placed near the tracheae in the pupa.[198] It appears probable that the "wing-ribs" found in the nervures (Fig. 170, A _fr_ and B) are the final state of these cylinders, but the origin and import of the cylinders are still unknown.

[Illustration: Fig. 174—Transverse section of part of the newly disclosed chrysalis of _Pieris brassicae_, showing the position and structure of the wings, hanging from one side of the body. _aa_, Anterior wing; _ap_, posterior wing; _e_, _e_, peritracheal spaces; _t_, _t_, tracheae. (After Gonin.)]

The formation of the scales of the wing commences very early—apparently soon after the casting of the larval skin—though the completion of the scales and their pigmentation is delayed to a late period of the pupal life. The scales are formed by special cells of the hypodermis that are placed deeper in the interior of the wing than the other hypodermal cells. Each scale is formed by one cell, and protrudes through the overlying hypodermis; the membrane into which the scales are inserted is a subsequently developed structure, and the beautiful {334}articulation of the scale with the wing takes place by a division of the stalk of the scale where it is encompassed by the membrane. Semper was not able to show that the scale-forming cells are certainly hypodermal cells, but this has since been demonstrated by Schäffer, who also shows that each of the cells contains an excretory vesicle.

[Illustration: Fig. 175.—Early condition of scales and nervures. (After Semper.) A, Section of portion of wing of pupa of _Sphinx pinastri_; _a_, basal membrane with trachea beneath it; _c_, scale-forming cell; _d_, early state of a scale; _e_, _e_, more advanced stages; _f_, hypodermal cells. B, part of a cellular cylinder that excretes the nervure [or more probably the rib or "Rippe" of Schäffer; cf. Fig. 170, B]; _b_, epithelial [hypodermal] cells; _a_, central string [supposed by Semper to be a nerve].]

Very little is positively known as to the development of the colour in the wing-scales. It has been pointed out by Hopkins[199] that in some cases the colours are of the nature of urates; that is, of excretory matter of the kind that usually passes from the body by direct channels, and in the case of Lepidoptera, by the Malpighian tubes. Miss Newbigin suggests that the organic pigments used in scale-coloration will be found to be of two kinds, urates and melanins, the urates being derivatives from nitrogenous, the melanins from carbonaceous, matters.[200] Marchal, who has devoted a great deal of attention to the study of the Malpighian tubes, informs us that the subdermal pigments of caterpillars are frequently in large part deposits of urates, and he is of opinion that, the function of the Malpighian tubes being arrested at certain periods of the metamorphosis, elimination of the matter they separate when functionally active then takes place in a variety of other ways.[201] A similar condition as to the melanin-pigments and the respiratory functions appears also {335}probable. The scales when first formed are pallid, and the physiology of their pigmentation is not fully ascertained; it is, however, known that when the scales are pallid the hypodermis is either pigmented or in close contact with pigmentary matter, and that as the scales become coloured this pigmentation of the hypodermis diminishes; so that it is clear that the colour of the scales is obtained from matter in the interior of the developing wing, and probably by the agency of the hypodermis.

The pattern on the wings of Lepidoptera is formed before the emergence from the pupa. In the Tortoiseshell butterfly, according to Schäffer, it commences to appear about the ninth day of the pupal life, and the pattern is completed about the eleventh or twelfth day. He also states that the process varies in its rapidity, and this, he thinks, may depend on the previous condition of the larva. According to Buckell the pupa of _Nemeobius lucina_ is sufficiently transparent to allow the development of the colour of the imago to be watched. He says that the coloration occurred first in front; that its entire production occupied less than twenty-four hours, and only commenced about forty-eight hours before the imago emerged.[202] When the butterfly leaves the pupal skin the wings are soft, crumpled sacs, of comparatively small size, but, as everyone knows, they rapidly expand and become rigid; the physiology of this process is apparently still unknown.

A great deal of evidence, both direct and indirect, has accumulated showing that the organisation of many Lepidoptera is excessively sensitive, so that slight changes of condition produce remarkable results; and it has also been shown that in the early part of the life this sensitiveness is especially great at the period of ecdysis. Numerous butterflies produce more than one generation a year, and sometimes the generations are so different that they have passed current with entomologists as distinct species. The phenomena of this character are styled "seasonal variations" or "seasonal dimorphism." It has, however, been shown that, by careful management, the eggs of a generation (say form _a_) may be made to produce form _a_, whereas in the usual course of nature they would produce form _b_. A very remarkable condition is exhibited by the North American _Papilio ajax_. There are three forms of the species, known as _P. ajax_, _P. telamonides_, {336}and _P. marcellus_. It is uncertain how many generations there may be in one year of this species, as the length of the life-cycle varies greatly according to circumstances. But in West Virginia all the butterflies of this species that emerge from the chrysalis before the middle of April are the form _marcellus_; those produced between the middle of April and the end of May are _telamonides_; while those that appear after this are _ajax_. _P. telamonides_ is not, however, the offspring of _marcellus_, for both forms emerge from pupae that have passed through the winter (and are the offspring of _ajax_), those that emerge early being _marcellus_, those that appear later _telamonides_.

In various parts of Asia and Africa the butterflies produced during the wet season differ more or less markedly from those of the same species produced during the dry season. These are called "wet" and "dry season" forms. Their aetiology has not been investigated, this discovery being comparatively recent.

Turning to the early life we find that some larvae vary in colour, and that this variation is sometimes of a definite character, the larva being one of two different colours—green or brown. In other cases the variation of the species is less definitely dimorphic, a considerable range of variation being exhibited by the species. In tracing the life-histories of Lepidopterous larvae it is not rare to find species in which the larva abruptly changes its form and colour in the middle of its life, and so completely that no one would believe the identity of the individual in the two successive conditions had it not been shown by direct observation; in these cases the change in appearance is usually associated with a change in habits, the larva being, perhaps, a miner in leaves in its first stages, and an external feeder subsequently. In the case of the larval variation we have alluded to above, it is understood that there is no marked change of habits. Poulton has shown[203] that it is not infrequent for some of these latter kinds of variable larvae to change colour during life, and he considers that light or conditions of illumination, that he speaks of as "phytoscopic," are the inducing causes. Great difference is, however, exhibited according to species, some variable species not being so amenable to these influences as others are. In dimorphic forms the change was observed to take place at a moult, the larva changing its skin {337}and appearing of another colour. In some cases the result of the change was to bring the colour of the larva into harmony with its surroundings, but in others it was not so. During the final stage many larvae are susceptible, the result being made evident only when the pupa is disclosed. Variably coloured pupae of certain species of butterflies have long been known, and it has been shown that some of the varieties can be induced by changing the surroundings. The result of the changes is in certain cases correspondence between the colour of the individual and its surroundings. In the case of other species having pupae of variable colour, the colour of the pupa is without relation to, or harmony with, the surroundings.

Experiments have been made on pupae by Merrifield and others, with the result of showing that by changes of temperature applied at certain moments some of the colours or marks of the butterfly that will emerge can be altered.

It is found that in certain localities the colour of various kinds of butterflies more or less agrees, while it differs from that of the same butterflies found in other localities. Thus Weir speaks of a duskiness common to various butterflies in Java, and calls it "phaeism"; and Bates states that in the Amazon valley numerous species of butterflies vary in a similar manner, as regards colour, in a locality. This phenomenon is now called "homoeochromatism," and is supposed to be due to the effect of local conditions on a susceptible organisation, though there is no experimental evidence of this.

MIMICRY.—There are many cases in Lepidoptera of species that depart more or less strongly in appearance from those forms to which they are considered to be allied, and at the same time resemble more or less closely species to which they are less allied. This phenomenon is called mimicry.[204] Usually the resembling forms are actually associated during life. Bates, who observed this phenomenon in the Amazon valley, thought that it might be accounted for by the advantage resulting to the exceptionally coloured forms from the resemblance;[205] it being assumed that these were unprotected, while the forms they resembled were {338}believed to be specially protected by nauseous odours or taste. It was, in fact, thought that the destroying enemies were deceived by the resemblance into supposing that the forms that were in reality edible were inedible. This subject has been greatly discussed, and in the course of the discussion numerous cases that could not be accounted for by Bates's hypothesis have been revealed. One of these is the fact that resemblances of the kind alluded to very frequently occur amongst inedible forms. This also has been thought to be accounted for by a supposed advantage to the Insects; it being argued that a certain number of "protected" forms are destroyed by enemies the instincts of which are faulty, and which therefore always require to learn by individual experience that a certain sort of colour is associated with a nasty taste. The next step of the argument is that it will be an advantage to a protected butterfly to form part of a large association of forms having one coloration, because the ignorant enemies will more easily learn the association of a certain form of coloration with nastiness; moreover such destruction as does occur will be distributed over a larger number of species, so that each species of a large, similarly coloured, inedible association will have a less number of its individuals destroyed. It is scarcely a matter for surprise that many naturalists are very sceptical as to these explanations; especially as the phenomena are supposed to have occurred in the past, so that they cannot be directly verified or disproved. It has not, however, been found, as a matter of fact, that even unprotected butterflies are much destroyed in the perfect state by birds. Moreover, in endeavouring to realise the steps of the process of development of the resemblance, we meet with the difficulty that the amount of resemblance to the model that is assumed to be efficient at one step of the development, and to bring safety, is at the next step supposed to be inefficient and to involve destruction. In other words, while analysis of the explanation shows that it postulates a peculiar and well-directed discriminative power, and a persistent selection on the part of the birds, observation leads to the belief that birds have been but little concerned in the matter. If we add to this that there is no sufficient evidence that the species now similar were ever dissimilar (as it is supposed they were by the advocates of the hypothesis), we think it is clear that the explanation from our point of view is of but {339}little importance.[206] The comparatively simple, hypothetical explanation, originally promulgated by Bates, is sometimes called Batesian mimicry; while the "inedible association" hypothesis is termed Müllerian mimicry.

There is one branch of the subject of mimicry that we think of great interest. This is the resemblance between Insects of different Orders; or between Insects of the same Order, but belonging to groups that are essentially different in form and appearance. It is not infrequent for beetles to resemble Hymenoptera, and it is still more frequent for Lepidoptera to resemble Hymenoptera, and that not only in colour and form, but also in movements and attitude. Druce says: "Many of the species of Zygaenidae are the most wonderful of all the moths; in some cases they so closely resemble Hymenoptera that at first sight it is almost impossible to determine to which Order they belong."[207] W. Müller says: "The little Lepidoptera of the family Glaucopides, that are so like certain wasps as to completely deceive us, have when alive exactly the same manner of holding their wings, the same restless movements, the same irregular flight as a wasp."[208] Seitz and others record a case in which a Brazilian _Macroglossa_ exactly resembles a humming-bird, in company with which it flies; and the same naturalist also tells us[209] of a Skipper butterfly that greatly resembles a grasshopper of the genus _Tettix_, and that moreover makes movements like the jumping of grasshoppers. In most of these cases the probabilities of either original similarity, arrested evolution, or the action of similar conditions are excluded: and the hypothesis of the influence, by some means or other, of one organism on another is strongly suggested.

The CLASSIFICATION of Lepidoptera was said by Latreille a century ago to be a reproach to entomologists. Since that time an enormous number of new species and genera have been described, but only recently has much advance been made in {340}the way of improvement of classification. The progress made has been limited to a better comprehension and definition of the families. The nervuration of the wings is the character most in vogue for this purpose. As regards the larger groups, and Phylogeny, there is a general opinion prevalent to the effect that Micropterygidae, Eriocephalidae and Hepialidae are in a comparatively primitive condition, but as to the relations of these families one with the other, or with other Lepidoptera, there is a wide difference of opinion.

[Illustration: Fig. 176—Clubs of butterflies' antennae. Terminal portions of antenna of, 1, _Pieris brassicae_; 2, _Styx infernalis_; 3, _Hestia idea_ (sub-family Danaides); 4, _Eudamus proteus_, and 5, _Limochores taumas_ (Hesperiidae). (After Schatz and Scudder.)]

The primary divisions of the family most often met with in literature are:—either Rhopalocera (= butterflies) and Heterocera (= moths); or Macrolepidoptera and Microlepidoptera; the Macrolepidoptera including the butterflies and large moths, the Microlepidoptera being limited to the families Tineidae (now itself in process of division into numerous families) and Tortricidae; some entomologists including also Pyralidae, Pterophoridae and Orneodidae in Microlepidoptera. The division of all Lepidoptera into two series is merely a temporary device necessitated by imperfect acquaintance with morphology. The division into Macro- and Micro- lepidoptera is entirely unscientific.

Series 1. _Rhopalocera_ or Butterflies.—Antennae knobbed at the tip or thickened a little before the tip, without pectinations, projecting processes, or conspicuous arrangements of cilia. Hind wings without a frenulum, but with the costal nervure strongly curved at the base (Fig. 161, II, B).

Series II. _Heterocera_ or Moths.—Antennae various in form, only rarely knobbed at the tip, and in such cases a frenulum present. In the large majority a frenulum is present, and the costal nervure of the hind-wing is either but little arched at the base (as in Fig. 161, I, B) or it has a large area between it and the front margin; but in certain families the hind wing is formed much as in Rhopalocera.

{341}It may be inferred from these definitions that the distinction between the two sub-Orders is neither sharply defined nor of great importance. The club of the antenna of the Rhopalocera exhibits considerable variety in form (Fig. 176).[210] Butterflies are as a rule diurnal in their activity and moths nocturnal; but in the tropics there are numerous Heterocera that are diurnal, and many of these resemble butterflies not only in colour but even in the shapes of their wings.

SERIES I. RHOPALOCERA. BUTTERFLIES.

CLASSIFICATION AND FAMILIES OF BUTTERFLIES. Although considerable unanimity exists as to the natural groups of butterflies, there is much diversity of opinion as to what divisions are of equivalent value—some treating as sub-families groups that others call families—and as to the way the families should be combined. There is, however, a general agreement that the Hesperiidae are the most distinct of the families, and E. Reuter considers them a distinct sub-Order with the name Grypocera.[211]

Four categories may be readily distinguished, as follows, viz:—

1. The majority of butterflies; having the first pair of legs more or less strikingly different from the other pairs; frequently very much smaller and not used as legs; when not very small, then differing according to sex of the same species, being smaller in the male than in the female; the part most peculiar is the tarsus, which is modified in various manners, but in the males of this great series is always destitute of its natural form of a succession of simple joints five in number. There is no pad on the front tibia. Fam. Nymphalidae, Erycinidae, Lycaenidae. [The distinctions between these three families are found in the amount and kind of the abortion of the front legs; for definition refer to the heading of each of the families.]

2. The front legs are in general form like the other pairs; their tibiae have no pads; the claws of all the feet are bifid, and there is an empodium in connection with them. Fam. Pieridae.

3. The front legs are like the other pairs; their tibiae however possess{342} pads; the claws are large, not bifid, and there is no empodium; the metanotum is completely exposed at the base of the abdomen. Fam. Papilionidae.

4. The front legs are like the other pairs; their tibiae however possess pads; the claws are small, toothed at the base, and there is an empodium; the metanotum is concealed by the prolonged and overhanging mesonotum. Fam. Hesperiidae.

The relations between the families Erycinidae, Lycaenidae, and Nymphalidae are very intimate. All these have the front legs more or less modified, and the distinctions between the families depend almost entirely on generalisations as to these modifications. These facts have led Scudder to associate the Lycaenidae and Erycinidae in one group, which he terms "Rurales." It is however difficult to go so far and no farther; for the relations between both divisions of Rurales and the Nymphalidae are considerable. We shall subsequently find that the genus _Libythea_ is by many retained as a separate family, chiefly because it is difficult to decide whether it should be placed in Erycinidae or in Nymphalidae. Hence it is difficult to see in this enormous complex of seven or eight thousand species more than a single great Nymphalo-Lycaenid alliance. The forms really cognate in the three families are however so few, and the number of species in the whole is so very large, that it is a matter of great convenience in practice to keep the three families apart. It is sufficient for larger purposes to bear in mind their intimate connexions.

The Papilionidae and Pieridae are treated by many as two sub-divisions of one group. But we have not been able to find any justification for this in the existence of forms with connecting characters. Indeed it would, from this point of view, appear that the Pieridae are more closely connected with the Lycaenidae and Erycinidae than they are with Papilionidae; in one important character, the absence of the pad of the front tibia, the Nymphalo-Lycaenids and the Pierids agree. It has also been frequently suggested that the Papilionidae (in the larger sense just mentioned) might be associated with the Hesperiidae. But no satisfactory links have been brought to light; and if one of the more lowly Hesperiids, such as _Thanaos_, be compared with one of the lower Papilionidae, such as _Parnassius_, very little approximation can be perceived.

{343}It appears, therefore, at present that Hesperiidae, Papilionidae, Pieridae, and the Nymphalo-Lycaenid complex are naturally distinct. But in the following review of the families and sub-families of butterflies, we shall, in accordance with the views of the majority of Lepidopterists, treat the Lycaenidae and Erycinidae as families distinct from both Nymphalidae and Pieridae.[212]

The number of described species of butterflies is probably about 13,000; but the list is at present far from complete; forms of the largest size and most striking appearance being still occasionally discovered. Forty years ago the number known was not more than one-third or one-fourth of what it is at present, and a crowd of novelties of the less conspicuous kinds is brought to light every year. Hence it is not too much to anticipate that 30,000, or even 40,000 forms may be acquired if entomologists continue to seek them with the enthusiasm and industry that have been manifested of late. On the other hand, the species of Rhopalocera seem to be peculiarly liable to dimorphic, to seasonal and to local variation; so that it is possible that ultimately the number of true species—that is, forms that do not breed together actually or by means of intermediates, morphological or chronological—may have to be considerably reduced.

In Britain we have a list of only sixty-eight native butterflies, and some even of these are things of the past, while others are only too certainly disappearing. New Zealand is still poorer, possessing only eighteen; and this number will probably be but little increased by future discoveries. South America is the richest part of the world, and Wallace informs us that 600 species of butterflies could, forty years ago, be found in the environs of the city of Pará.

FAM. 1. NYMPHALIDAE.—_The front pair of legs much reduced in size in each sex, their tarsi in the male with but one joint, {344}though in the female there are usually five but without any claws. Pupa suspended by the tail so as to hang down freely._ We include in this family several sub-families treated by some taxonomists as families; in this respect we follow Bates, whose arrangement[213] still remains the basis of butterfly classification. With this extension the Nymphalidae is the most important of the families of butterflies, and includes upwards of 250 genera, and between 4000 and 5000 species. There are eight sub-families.

It is in Nymphalidae that the act of pupation reaches its acme of complication and perfection; the pupae hang suspended by the tail, and the cremaster, that is the process at the end of the body, bears highly-developed hooks (Fig. 177, C, D). The variety in form of the chrysalids is extraordinary; humps or processes often project from the body, making the Insect a fantastic object; the strange appearance is frequently increased by patches like gold or silver, placed on various parts of the body. It is believed that the term chrysalid was first suggested by these golden pupæ. The Purple Emperor, _Apatura iris_, differs strikingly in the pupa as well as in the larva-stage from all our other Nymphalids; it is of green colour, very broad along the sides, but narrow on the dorsal and ventral aspects (Fig. 177). The skin of this pupa is less hard than usual, and the pupa seems to be of a very delicate constitution. The Purple Emperor, like some of the Satyrides as well as some of its more immediate congeners, hibernates in our climate as a partially grown larva and passes consequently only a very brief period of its existence in the form of a pupa.

[Illustration: Fig. 177.—Pupa of the Purple Emperor butterfly, _Apatura iris_. New Forest. A, Lateral, B, dorsal aspect; C, enlarged view of cremaster with the suspensory hook; D, one hook still more enlarged.]

SUB-FAM. 1. DANAIDES.—_Front wing with inner-margin {345}(submedian) nervure, with a short fork at the base. Cell of hind wing closed. Front foot of the female ending in a corrugate knob. Caterpillars smooth, provided with a few long fleshy processes._ The claws are in a variable state, being sometimes simple, as in Papilionidae, sometimes with an empodium, apparently of an imperfect kind. The Danaides are usually large Insects with an imperfect style of ornament and colour; they have a great deal of black or very dark scaling, and in some _Euploea_ this is agreeably relieved by a violet or purple suffusion, and these are really fine Insects. Usually there are large pale spaces, of some neutral indefinite tint, on which black blotches are distributed in a striking but inartistic manner. In many of the species the markings are almost spot for spot the same on the upper and under sides. About seven genera and 250 species are recognised. Danaides occur in all the warmer parts of the world, but are most numerous in the Eastern tropics. In Europe the family is represented only by an Asiatic and African species, _Limnas chrysippus_, that has extended its range to Greece. Besides this another species, _Anosia erippus_, Cr. (unfortunately also called _Anosia menippe_, Hb., and _Danais archippus_ or even _D. plexippus_) has in the last two or three decades extended its range to various islands and distant localities, concomitantly, it is believed, with an extension of the distribution of its food-plant, _Asclepias_. This Insect has several times been taken in this country, and may probably be a natural immigrant. It is a common butterfly in North America, where it is called the Monarch.[214]

Some, at least, of the Danaides are unpleasant to birds in odour or in taste, or both. Among them there occur, according to Moore[215] and others, numerous cases of resemblance between forms that are thus protected. It is possible that the odour and taste are of some value to the Insects;[216] as, however, butterflies of any kind appear to be but rarely attacked in the imago-state by birds, and as their chief enemies are parasitic Insects that attack the larval instar, it is impossible to consider this protection of such prime importance to the species as many theorists assume it to be.

{346}[Illustration: Fig. 178—_Ithomia pusio._ Brazil.]

SUB-FAM. 2. ITHOMIIDES.—_Differs from Danaides by the female front foot having a true, though somewhat abbreviate tarsus. The caterpillers have no long processes._ There has been considerable difference of opinion as to this division of butterflies. It is the family Neotropidae of Schatz, the Mechanitidae of Berg; also the "Danaioid Heliconiidae" of several previous writers, except that _Ituna_ and _Lycorea_ do not belong here but to Danaides. Godman and Salvin treat it as a group of the Danaid sub-family. The Ithomiides are peculiar to tropical America, where some 20 or 30 genera and about 500 species have been discovered. There is considerable variety amongst them. _Ithomia_ and _Hymenitis_ are remarkable for the small area of their wings, which bear remarkably few scales, these ornaments being in many cases limited to narrow bands along the margins of the wings, and a mark extending along the discocellular nervule. Wallace says they prefer the shades of the forest and flit, almost invisible, among the dark foliage. Many of these species have the hind-wings differently veined in the two sexes on the anterior part, in connection with the existence in the male of peculiar fine hairs, placed near the costal and subcostal veins. _Tithorea_ and other forms are, however, heavily scaled insects of stronger build, their colours usually being black, tawny-red or brown, yellow, and white. In the sub-fam. Danaides, according to Fritz Müller, the male has scent-tufts at the extremity of the abdomen, whereas in Ithomiides analogous structures exist on the upper side of the hind-wing. Ithomiides have various colour-resemblances with members of the Heliconiides and Pieridae; _Tithorea_ has colour analogues in _Heliconius_, and _Ithomia_ in _Dismorphia_ (formerly called _Leptalis_). Crowds of individuals of certain species of _Ithomia_ are occasionally met with, and mixed with them there are found a small number of examples of _Dismorphia_ coloured like themselves. They are placed by Haase in his category of secondary models. Belt states that some Ithomiides are distasteful to monkeys and spiders, but are destroyed by Fossorial Hymenoptera, which use the butterflies as food for their young; and he also says that {347}they are very wary when the wasp is near, and rise off their perches into the air, as if aware that the wasp will not then endeavour to seize them. Much information is given about the habits by Bates in the paper in which he first propounded the "theory of mimicry."[217] The larvae are said to live on Solanaceae.

The genus _Hamadryas_ is placed by some writers in Danaides, by others in Ithomiides; and Haase has proposed to make it the group "Palaeotropinae." The species are small, black and white Insects, somewhat like Pierids. They are apparently hardy Insects, and are abundant in certain parts of the Austro-Malay region.

SUB-FAM. 3. SATYRIDES.—_Palpi strongly pressed together, set in front with long, stiff hairs. Front wings frequently with one or more of the nervures swollen or bladder-like at the base of the wing. Cells of both wings closed. Caterpillar thickest at the middle, the hind end of the body bifid. Pupa generally suspended by the cremaster, without girth: but sometimes terrestrial._ This is a very extensive group, consisting of upwards of 1000 species. The Insects are usually of small size, of various shades of brown or greyish colours, with circular or ringed marks on the under sides of the wings. It is found all over the world, and is well represented in Europe; our Meadow-browns, Heaths, and Marbled-whites, as well as the great genus _Erebia_ of the highlands and mountains belonging to it. Most of these Insects have but feeble powers of flight, and rise but little from the surface of the ground. The caterpillars live on various grasses. They are usually green or brown, destitute of armature, and a good deal like the caterpillars of Noctuid moths, but the hind end of the body is thinner and divided to form two corners, while the head is more or less free, or outstanding. The pupae are of great interest, inasmuch as in a few cases they do not suspend themselves in any way, but lie on the ground; sometimes in a very feeble cocoon or cell. There are no cremasteral hooks. The pupae of the Grayling butterfly, _Hipparchia semele_, has been found in loose soil a quarter of an inch below the surface. The chrysalis of the Scotch Argus, _Erebia aethiops_, was found by Mr. Buckler to be neither suspended nor attached, but placed in a perpendicular position, head upwards, amongst the grass. {348}In the majority of cases the pupa is, however, suspended as is usual in Nymphalidae. Nothing is known as to the nature of the peculiar inflation of the bases of the nervures of the front wings; it is well shown in our common species of _Coenonympha_; this character is not, however, constant throughout the family. There is in South America a very remarkable group of Satyrides consisting of the genera _Cithaerias_ and _Haetera_, in which the wings are very delicate and transparent, bearing on the greater part of their area remote fine hairs instead of scales; there are nevertheless some scaled patches about the margins, and one or more of the ringed marks characteristic of the Satyrides; while in some species the distal portions of the hind wings are tinted with carmine. The species of the genus _Pierella_ connect these transparent Satyrids with the more ordinary forms. According to Wallace the habits of these fairy-like forms are those characteristic of the family in general. The genus _Elymnias_ has been separated by some authorities as a sub-family, or even as a family, Elymniidae, chiefly on the ground of a slight peculiarity in the termination of the branches of the veins at the outer angle of the front wings. The _Elymnias_ are said to be of a mimetic nature, having a greater or less resemblance to butterflies of various other divisions; there is also a considerable difference in appearance between their own sexes. The larva of _E. undularis_ is known; it is of the form usual in Satyrides, and lives on the palm _Corypha_. About 50 species, ranging from India to Australia, with two in Africa, are known of this interesting group.

SUB-FAM. 4. MORPHIDES.—_There is no cell on the hind wing, the discocellular nervule being absent_ (Fig. 161, II. B). _Caterpillars smooth or spiny, with the extremity of the body divided; frequently gregarious._ These Insects have become notorious from the extraordinary brilliancy of blue colour exhibited by the upper surface of the wings of the typical genus _Morpho_. The species of _Morpho_ are all Insects of large size, but with wings enormous in proportion to the body; this latter part is carried in a sort of cradle formed by the inner parts of the margins of the hind wings. Although an arrangement of this kind is seen in numerous other butterflies, yet there is perhaps none in which it is carried to quite such a pitch of perfection as it is in _Morpho_, where, on the under surface no part of the body behind the posterior legs can {349}be seen. There are only about 100 species of Morphides, and 50 of these are included in _Morpho_, which is peculiar to tropical and sub-tropical America; the other half of the family is divided among ten or twelve genera, found in the Indo-Malay region; there being none in Africa. The eastern Morphides, though fine Insects, are not to be compared, either in size or brilliancy, with their American allies. The species of _Morpho_ are apparently found only in the great forests of South America, where they are far from rare; some have a flapping and undulating flight, straight onwards along the alleys of the forest, and near the ground; others are never seen except steadily gliding with outstretched wings from 20 to 100 feet above the ground, where they move across sunny spaces between the crowns of the taller trees; the low-flyers settle frequently on the ground to suck the juices from fallen fruit, but the members of the other section never descend to the ground. As regards the caterpillars, W. Müller tells us[218] that the spines they are armed with break off, and enter the skin, if the creatures are carelessly handled. Four of the five species known to him are conspicuously coloured with black, red, yellow and white. The individuals are gregarious. The larvae of _M. achilles_ sit in companies, often of more than 100 individuals, on trunks of trees, and so form a conspicuous patch. The caterpillars of _M. epistrophis_ hang together as red clumps on the twigs of their food-plants. Hence it appears that in this genus we have an exception to the rule that night-feeding caterpillars rest in a hidden manner during the day.

SUB-FAM. 5. BRASSOLIDES.—_Large butterflies, with the cell of the hind wing closed, and usually with a small adjoining prediscoidal cell. Larva not very spiny; thinner at the two ends, the tail bifid, the head perpendicular and margined with spines._ This small sub-family includes less than 100 species arranged in about eight genera, all South American. They have the very unusual habit of resting during the day like moths, becoming active only late in the afternoon. They are truly noble Insects; although not possessed of the brilliant colours of _Morpho_, they are adorned, especially on the under surface, with intricate lines and shades most harmoniously combined, while the upper surface is frequently suffused with blue or purple. This sub-family {350}attains its highest perfection in the genus _Caligo_; they are enormous Insects, and some of them not rare. The larva of _C. eurylochus_ (Fig. 179) during early life is green, and sits on the leaf of a _Musa_, but after the third moult it becomes brown and hides itself among the dry leaves. It is common in the gardens of Rio de Janeiro, where its pupae are found on the walls, like those of our white butterflies here.

SUB-FAM. 6. ACRAEIDES.—_Submedian nervure of fore wings not forked at the base; the median without spur. Cells closed. Palpi in section cylindric, sparingly set with hairs. Larva armed with branched spines._ A somewhat monotonous and uninteresting division; the size is moderate or small, and the colours not artistic, but consisting of ill-arranged spots; the under side of the hind wings very frequently diversified by numerous line-like marks, radiately arranged, and giving place at the base to a few spots. There are about 200 species known, of which the majority are African; there are but few Oriental or South American species. Some authorities consider there is only one genus, but others prefer to adopt seven or eight divisions. _Alaena_ is now placed in Lycaenidae, though until recently it was considered to belong here. The females of some species possess an abdominal pouch somewhat similar to that of _Parnassius_.

The members of this sub-family are considered to be of the protected kind.

[Illustration: Fig. 179—Larva of _Caligo_ (_Pavonia_) _eurylochus_. Rio de Janeiro. × 1. (After Burmeister.)]

{351}SUB-FAM. 7. HELICONIIDES.—_Submedian nervure of front wing not forked; median with a short spur near the base. Cell of hind wing closed by a perfect nervule. Palpi compressed, with scales at the sides, in front covered with hairs. Male with an elongate unjointed, female with a four-jointed, front tarsus. Caterpillars set with branched spines._ This family is peculiar to tropical America and consists of only two genera, _Heliconius_ and _Eueides_, with about 150 species; but it is one of the most characteristic of the South American groups of Butterflies. It is very closely allied to the Nymphalides, especially to the genera _Metamorpha_ and _Colaenis_, but is readily distinguished by the perfectly-formed nervules that close the wing-cells. The wings are longer and narrower than in Nymphalides, and the colour, though exhibiting much diversity, is on the whole similar to that of the heavily-scaled forms of Ithomiides of the genera _Tithorea_, _Melinaea_, _Melanitis_; there being in several cases a great resemblance between species of the two groups. A frequent feature in one group of _Heliconius_ is that the hind wing bears a patch of red prolonged outwards by angular radiating marks. The individuals of certain species—_H. melpomene_ and _H. rhea_—are known to execute concerted dances, rising and falling in the air like gnats; when some of them withdraw from the concert others fill their places. _H. erato_ exhibits the very rare condition of trichroism, the hind wings being either red, blue, or green. Schatz states that the different forms have been reared from a single brood of larvae. The caterpillars of Heliconiides live on Passiflorae, and are said to be very similar to our European _Argynnis_-caterpillars. The chrysalids are very spinous. We may here remark that considerable confusion exists in entomological literature in consequence of Ithomiides having been formerly included in this sub-family; for remarks formerly made as to "Heliconiides," but that really referred only to Ithomiides, have been interpreted as referring to Heliconiides of the present system.

The Heliconiides seem remarkably plastic as regards colour, and are therefore exponents of "homoeochromatism." Bates says, as regards them: "In tropical South America a numerous series of gaily-coloured butterflies and moths, of very different families, which occur in abundance in almost every locality a naturalist may visit, are found all to change their hues and markings together, as if by the touch of an enchanter's wand, at {352}every few hundred miles, the distances being shorter near the eastern slopes of the Andes than nearer the Atlantic. So close is the accord of some half-dozen species (of widely different genera) in each change, that he had seen them in large collections classed and named respectively as one species."[219] Many of them are believed to be permeated by nauseous fluids, or to possess glands producing ill-smelling secretions.

SUB-FAM. 8. NYMPHALIDES.—_Cells, of both front and hind wing, either closed only by imperfect transverse nervules or entirely open. Front tarsus of the male unjointed and without spines, of the female four- or five-jointed. Caterpillar either spined or smooth; in the latter case the head more or less strongly horned or spined, and the apex of the body bifid._ This sub-family is specially characterised by the open cells of the wings; the discocellulars, even when present, being frequently so imperfect as to escape all but the most careful observation. The Nymphalides include upwards of 150 genera and 2000 species. The divisions having smooth larvae are separated by Kirby[220] and others as a distinct sub-family (Apaturides). In Britain, as in most other parts of the world, Nymphalides is the predominant group of butterflies. We have eighteen species, among which are included the Fritillaries, Admirals, Purple Emperor, and the various _Vanessa_—Peacock, Camberwell Beauty, Red Admiral, Tortoise-shells, and Painted Lady. All have spined caterpillars except the Emperor. In the temperate regions of the northern hemisphere Vanessa may be considered the dominant butterflies, they being very numerous in individuals, though not in species, and being, many of them, in no wise discomfited by the neighbourhood of our own species. Several of them are capable of prolonging and interrupting their lives in the winged condition to suit our climate; and this in a manner that can scarcely be called hibernation, for they frequently take up the position of repose when the weather is still warm, and on the other hand recommence their activity in the spring at a very early period. This phenomenon may frequently be noticed in the Tortoise-shell butterfly; it is as if the creature knew that however warm it may be in the autumn there will be no more growth of food for its young, and that in the spring vegetation {353}is sure to be forthcoming and abundant before long, although there may be little or none at the time the creature resumes its activity. It is probable that the habit may be in some way connected with an imperfect activity of the sexual organs. It should, however, be recollected that many larvae of butterflies hibernate as young larvae after hatching, and, sometimes, without taking any food. _Pyrameis cardui_, the Painted Lady, is, taking all into consideration, entitled to be considered the most ubiquitous of the butterfly tribe. Its distribution is very wide, and is probably still extending. The creature is found in enormous numbers in some localities, especially in Northern and Eastern Africa; and when its numbers increase greatly, migration takes place, and the Insect spreads even to localities where it cannot maintain itself permanently. In Britain it is probably during some years nearly or quite absent, but may suddenly appear in large numbers as an immigrant. The favourite food of the larva is thistles, but many other plants serve the Insect at times.

_Vanessa_, or _Pyrameis_,[221] _atalanta_, the Red Admiral, is common in the Palaearctic and Nearctic regions, and extends its range to various outlying spots. The most remarkable of these is the remote Hawaiian Islands, where the Insect appears really to be now at home, though it is associated with a larger and more powerful congener, _P. tameamea_. Another interesting Vanessid is _Araschnia levana_, which is peculiar to Europe, where it produces annually two generations so dissimilar to one another that they passed current as two species, _V. levana_ and _V. prorsa_. Although intermediate forms are rare in nature they can be induced by certain treatments applied to the larvae under human control.

The dead-leaf butterflies of the genus _Kallima_ belong to Nymphalides. They are so shaped and coloured that when settled, with wings closed, on a twig, the appearance is exactly that of a dry leaf; the exposed surface is mottled with spots that look just like the patches of minute fungi, etc. that are so common on decaying vegetation. The colour and the spots on the under surface of this butterfly are very variable. According to Mr. Skertchly,[222] we may presume that in the minute details of {354}these resemblances we have a case of hypertely similar to that of the resemblance to Insects' minings exhibited by certain marks on the tegmina of _Pterochroza_ (mentioned in Vol. V. p. 322).

In South America there is a somewhat peculiar genus of Nymphalides—_Ageronia_—that delights in settling on the trunks of trees rather than on flowers or leaves. It was long since noticed that the the species of _Ageronia_ make a clicking noise; in some cases when on the wing, in other cases by moving the wings when the Insect is settled. The object of the noise is quite uncertain; it has been suggested that it is done in rivalry or courtship, or to frighten away enemies. Bigg-Wether found, however, that in South Brazil there is a lazy little bird to which this sound serves as a signal, inducing it to descend from its perch and eat the clicker. The mode in which the noise is produced is not quite clear. Sir George Hampson has pointed out[223] that the fore wing bears at the extreme base a small appendage bearing two hooks, and that two other processes on the thorax play on these when the wing moves. His suggestion that these hooks are the source of the sound seems highly probable.

There is a great variety in the larvae of Nymphalides. In the _Vanessa_ group the body is armed with spines, each one of which bears shorter thorns, the head being unadorned. The Fritillaries (_Argynnis_, _Melitaea_) also have caterpillars of this kind. In many other forms the head itself is armed with horns or spines of diverse, and frequently remarkable, character. In _Apatura_ and its allies the body is without armature, but the head is perpendicular, the vertex bifid and more or less prolonged. The caterpillar of our Purple Emperor, _Apatura iris_, is quite unlike any other British caterpillar; in colour it is like a Sphingid larva—green with oblique lateral stripes of yellow and red—but in form it is slug-like, pointed behind, and it has on the head two rather long tentacle-like horns. In the South American genus _Prepona_, the larva of which in general form resembles that of _Apatura_ there are no anal claspers, but the extremity of the body is prolonged, forming a sort of tail.

FAM. 2. ERYCINIDAE (LEMONIIDAE of some authors).—_The female has six perfectly formed legs, though the front pair is smaller. The male has the coxae of the front legs forming a spine, and the tarsi unjointed, without claws._ This family consists of about 1000 {355}species, usually of rather small size, exhibiting a great variety of shape and coloration, some of them being remarkably similar to some of the gay, diurnal moths of South America. The palpi are usually small, but in _Ourocnemis_ they are large and porrect. The family is specially characteristic of tropical America, but there is one small group of 30 or 40 species, _Nemeobiides_, in the Eastern Hemisphere. We have one species in Britain, _Nemeobius lucina_, the Duke of Burgundy Fritillary. Neither the larvae nor the pupae of Erycinidae present any well-marked characteristic feature, but exhibit considerable variety. According to Bar,[224] some of the larvae are like those of moths; the caterpillar of _Meliboeus_ is said to be like that of a _Liparis_: the chrysalis has the short, rounded form of that of the _Lycaenidae_, and is suspended with the head down, and without a band round the body. The larvae of _Eurygona_ are gregarious. The pupae of some other forms adhere, heads downwards, to branches. Scudder considers that this family is not distinct from Lycaenidae, and that the Central American genus _Eumaeus_ connects the two. Reuter also treats Erycinidae as a division of Lycaenidae.

SUB-FAM. 1. ERYCINIDES.—[_Characters of the family._] _Palpi not unusually large._ We place all the Erycinidae in this sub-family except the following—

SUB-FAM. 2. LIBYTHEIDES.—_Butterflies of average size, with the palpi large and porrect: the front legs of the male small, the tarsus reduced to one joint: the front leg of the female of the normal structure, and but little reduced in size._ This division consists of the single genus _Libythea_, with only a score of species. They are Insects somewhat like _Vanessa_ in appearance, but cannot fail to be recognised on account of the peculiar palpi. The genus is of very wide distribution, occurring in most parts of the warm and temperate continental regions, and it also occurs in Mauritius and the Antilles.

The Libytheides have given rise to much difference of opinion amongst systematists, some of whom assign them as a sub-family to the Erycinidae, some to the Nymphalidae; while others treat them as a family apart. The families Nymphalidae, Erycinidae and Lycaenidae are so intimately allied, that Scudder is probably correct in considering them to form really one huge family; if this view were adopted there would be no difficulty {356}in locating _Libythea_ therein. If they be kept apart, it is almost necessary to separate _Libythea_ also; though possibly its claims to be placed in Erycinidae slightly preponderate. The recently described genus _Ourocnemis_ to some extent connects Erycinides with Libythaeides.[225]

FAM. 3. LYCAENIDAE.—_The front legs but little smaller than the others: in the male, however, the tarsus, though elongate, is only of one joint, and is terminated by a single claw. No pad on the front tibia. Claws not toothed._ The Lycaenidae, or Blues, are, as a rule, of small size, but in the tropics there are many that reach the average size of butterflies, _i.e._ something about the stature of the Tortoise-shell butterfly. The family is one of the larger of the divisions of butterflies, considerably more than 2000 species being at present known, and this number is still rapidly increasing. Although blue on a part of the upper surface is a very common feature in the group, it is by no means universal, for there are many "Coppers," as well as yellow and white Lycaenidae. Many species have delicate, flimsy appendages—tails—to the hind wings, but in many others these are quite absent; and there are even tailed and tailless forms of the same species. The members of the group Lipteninae (_Liptena_, _Vanessula_, _Mimacraea_, etc.) resemble members of other sub-families of Nymphalidae, and even of Pieridae. Lycaenidae are well represented wherever there are butterflies; in Britain we have 18 species.

The larvae of this family are very peculiar, being short, thicker in the middle, and destitute of the armature of spines so remarkable in many other caterpillars. It has of late years been frequently recorded that some of these larvae are attended by ants, which use their antennae to stroke the caterpillars and induce them to yield a fluid of which the ants are fond. Guénée had previously called attention[226] to the existence of peculiar structures contained in small cavities on the posterior part of the caterpillar of _Lycaena baetica_. These structures can be evaginated, and, it is believed, secrete a fluid; Edwards and M‘Cook are of opinion that they are the source of the matter coveted by the ants. The larvae are without spines.

The caterpillars of the Blues have some of them strange tastes; more than one has been recorded as habitually feeding on Aphidae {357}and scale-Insects. The pupae are, like the larvae, of short inflated form. By a remarkable coincidence, the pupae of two species bear a considerable resemblance to the heads of monkeys, or mummies. The Lycaenid pupa is usually extremely consolidated, destitute of movement, and is supported—in addition to the attachment by the cremaster—by a silk thread girdling the middle. There are exceptions to these rules, and according to Mr. Robson the pupa of _Tajuria diaeus_ hangs free, suspended from a leaf, and can move the body at the spot where the abdominal segments meet the wing-cases in the dorsal line.[227]

FAM. 4. PIERIDAE.—_The six legs well developed, and similar in the sexes; there is no pad on the front tibia. The claws of all the feet are bifid, or toothed, and there is an empodium._ There are upwards of 1000 species of Pieridae already known. Although several taxonomists treat the Pieridae and Papilionidae as only subdivisions of one family, yet they appear to be quite distinct, and the relationships of the former to be rather with Lycaenidae. In Pieridae, white, yellow, and red are the predominant colours, though there is much black also. It has recently been ascertained that the yellow and red pigments, as well as the white, are uric acid or derivatives therefrom.[228] The physiology of this peculiarity has not yet been elucidated, so that we do not know whether it may be connected with some state of the Malpighian vessels during metamorphosis.

Our Garden-White, Brimstone, Clouded-yellows and Orange-tip butterflies belong to this family; as does also the South American genus formerly called _Leptalis_. This generic name, which is much mentioned in literature owing to the resemblance of the species of the genus to _Heliconiides_, has now disappeared; _Leptalis_ having been divided into various genera, while the name itself is now considered merely a synonym of _Dismorphia_.

The African Insect, _Pseudopontia paradoxa_, has nearly transparent wings, no club to the antennae, a remarkably small cell on the wing, and an arrangement of the nervules not found in any other butterfly; there being only ten nervules at the periphery of the front wing, and both upper and lower radial nervules uniting with the posterior branch of the subcostal. It has been treated as a moth by several entomologists. Aurivillius considers that it {358}is certainly a butterfly; but as the metamorphoses are unknown, we cannot yet form a final opinion as to this curious form. The extraordinary Peruvian Insect, _Styx infernalis_, is also placed in this family by Staudinger; it is a small, pale Insect, almost white, and with imperfect scales; a little recalling a Satyrid. It appears to be synthetic to Pieridae and Erycinidae.

[Illustration: Fig. 180—Pupation of the Orange-tip butterfly, _Euchloe cardamines_. A, The completed pupa; B, the larva, with its girdle, prepared for the change.]

The caterpillars of Pieridae are perhaps the least remarkable or attractive of all butterfly-caterpillars; their skins are as a rule bare, or covered only with fine, short down or hair; their prevalent colour is green, more or less speckled with black and yellow, and they are destitute of any prominent peculiarities of external structure. Pupation is accomplished by the larva fixing itself to some solid body by the posterior extremity, with the head upwards (or the position may be horizontal), and then placing a girdle round the middle of the body. The pupa never hangs down freely as it does in Nymphalidae. It has been ascertained by experiment that if the girdle round the larva be cut, the pupation can nevertheless be accomplished by a considerable proportion of larvae. Some of the pupae are of very peculiar form, as is the case in the Orange-tip (Fig. 180, A) and Brimstone butterflies. The Orange-tip butterfly passes nine or ten months of each year as a pupa, which is variable in colour; perhaps to some extent in conformity with its surroundings. The North American _E. genutia_ has a similar life-history, but the larva leaves its Cruciferous food-plant, wanders to an oak tree, and there turns to a pupa, resembling in colour the bark of the tree.

[Illustration: Fig. 181—Newly-hatched larva of _Euchloe cardamines_. A, The larva in profile; B, one segment more magnified, showing the liquid-bearing setae; C, one of the setae still more magnified, and without liquid.]

It is not unusual for caterpillars to change their habits and {359}appearance in a definite manner in the course of the larval life. The caterpillar of _Euchloe cardamines_ exhibits a larval metamorphosis of a well-marked character. The young larva (Fig. 181) is armed with peculiar setae, furcate at the tip, each of which bears a tiny ball of fluid. In this stage the caterpillar makes scarcely any movement. In the middle of the caterpillar's life a new vestiture appears after an ecdysis; numerous fine hairs are present, and the fluid-bearing spines nearly disappear, being reduced to a single series of spines of a comparatively small size on each side of the upper middle region of the body (Fig. 182). The colour is also a good deal changed, and concomitantly there is a much greater voracity and restlessness.

[Illustration: Fig. 182—Larva of _Euchloe cardamines_ in middle life. A, the larva in profile; B, one segment more magnified.]

FAM. 5. PAPILIONIDAE.—_All the legs well developed. Claws large, simple, without empodium. Front tibiae with a pad. The metanotum free, conspicuously exposed between mesonotum and abdomen._ This series of butterflies includes some of the most magnificent of the members of the Insect world. It is considered by some authorities to be the highest family of butterflies; and in one very important feature—sexual differentiation—it certainly is entitled to the rank. There are about 700 recorded species, the larger portion of which are included in the genus _Papilio_. The great variety of form has led to this genus being divided; the attempts have, however, been partial, with the exception of an arrangement made by Felder, who adopted 75 sections, and a recent consideration of the subject by Haase, who arranges Felder's sections into three sub-genera. Many of the sections have received names, and are treated by some authors as genera, so that an unfortunate diversity exists as to the names used for these much-admired Insects. The genus is distributed all over the world, but is perhaps nowhere more numerous in species than in South America.

{360}[Illustration: Fig. 183—_Ornithoptera_ (_Schoenbergia_) _paradisea_, male. New Guinea. × 1. (Colours, velvet-black, golden-yellow and green.)]

Wallace informs us that the great majority of the species of the Amazon valley frequent the shady groves of the virgin forest. In many cases the sexes are extremely different in appearance and habits, and are but rarely found together in one spot. The genus _Ornithoptera_ is closely allied to _Papilio_, and contains some of the most remarkable of butterflies, the homes of the species being the islands of the Malay Archipelago, and outlying groups of islands, there being a smaller number of species in the neighbouring continents. The females are of great size, and are so excessively different from their consorts of the other sex, as to arouse in the student a feeling of surprise, and a strong desire to fathom the mysteries involved. {361}[Illustration: Fig. 184—_Ornithoptera (Schoenbergia) paradisea_, female. × 1. (The wings, on the right side, detached, showing the under surface. Colours, black, white, and gray.)]

{362}It would be difficult to surpass the effective coloration of the males in many of the species of _Ornithoptera_; they are, too, very diverse in this respect; _O. brookiana_ is of an intense black colour, with a band of angular green marks extending the whole length of its wings, while behind the head there is a broad collar of crimson colour. Perhaps the most remarkable of all is the _O. paradisea_, recently discovered in New Guinea; in this species the sexual disparity reaches its maximum. The female (Fig. 184) is a large, sombre creature of black, white and grey colours, but the male (Fig. 183) is brilliant with gold and green, and is made additionally remarkable by a long tail of unusual form on each hind wing.

We may anticipate that these extraordinary cases of sexual total dissimilarity in appearance are accompanied by equally remarkable habits and physiological phenomena. In the case of _O. brookiana_ the female is extremely rare, so that the collector, Künstler, could only obtain fifteen females to a thousand males. According to Mr. Skertchly, instead of the crowd of males being eager to compete for the females, the reverse is the case; the female diligently woos the male, who exhibits a reluctance to coupling. This observer apparently considered that the "emerald feathers" of the male are a guide or incitement to the female.[229]

In Africa _Ornithoptera_ is to a certain extent represented by two extremely remarkable forms, _Papilio zalmoxis_ and _P. (Drurya) antimachus_. There are about a dozen other genera of Papilionidae; most of them contain but few species. _Parnassius_, however, is rich in species inhabiting the mountains and elevated plateaus of the northern hemisphere in both the Old and New Worlds; it is remarkable for the small amount of scales on the wings, and for the numerous variations of the species. The female possesses a peculiar pouch at the end of the body; although only formed during the process of coupling, it has a special and characteristic form in most of the species. The curious Indian genus _Leptocircus_ has parts of the front wings transparent, while the hind pair form long tails. This genus is of interest in that {363}it is said to connect Papilionidae to some extent with Hesperiidae. The larvae of this family are remarkable on account of a curious process on the thoracic segment called an "osmeterium." It is usually retracted, but at the will of the caterpillar can be everted in the form of a long furcate or Y-shaped process; there is a gland in the osmeterium, and as a result a strong odour is emitted when the exstulpation occurs.

The pupation of Papilionidae is similar to that of Pieridae, the pupa being placed with the head upwards, fixed by the tail, and girt round the middle. A very curious diversity of pupation occurs in the genus _Thais_, in which the pupa is attached by the tail as usual, and—which is quite exceptional—also by a thread placed at the top of the head. Scudder thinks there is also a girdle round the middle, but Dr. Chapman inclines to the view that the thread attaching the head is really the median girdle slipped upwards. The pupation of _Parnassius_ is exceptional, inasmuch as, like Satyrides, it is terrestrial, in a slight construction of silk.

FAM. 6. HESPERIIDAE (_Skippers_).—_Six perfect legs: metanotum not free, largely covered by the mesonotum. A pad on the front tibia. Claws short and thick; empodium present._ Although this family has been comparatively neglected by entomologists, upwards of 2000 species and more than 200 genera are known, and it is not improbable that it may prove to be as extensive as Nymphalidae. We have already said that Hesperiidae is generally admitted to be the most distinct of the butterfly groups. It has been thought by some taxonomists to be allied to Papilionidae, but this is a mistake. It is undoubtedly more nearly allied to Heterocera, and when the classification of Lepidoptera is more advanced, so that the various natural groups placed in that sub-Order are satisfactorily distinguished, it is probable that Hesperiidae will be altogether separated from Rhopalocera. We have already mentioned that E. Reuter considers the Hesperiidae to be phylogenetically unconnected with Rhopalocera proper; but though quite ready to admit that he will probably prove correct in this, we think Lepidopterists will not be willing to recognise the family as a sub-Order equivalent in value to all Heterocera.

The body is shorter and thicker than it is in most butterflies, and is pointed at the tip rather than knobbed or bent downwards; the wings are less ample; the antennae are not truly {364}knobbed, but are thicker before the actual tip, which is itself pointed and more or less bent backwards, so that the antennae are somewhat hook-shaped.

In habits as well as structure the family is markedly distinct from butterflies; the pupation is peculiar, and the name Skipper has been applied to the perfect Insects, because so many of them indulge in a brief, jerky flight, instead of the prolonged aerial courses characteristic of the higher butterflies.

There is great difference among the members of the family, and some of them possess a very high development of the powers of locomotion, with a correspondingly perfect structure of the thoracic region, so that, after inspection of these parts, we can quite believe Wallace's statement that the larger and strong-bodied kinds are remarkable for the excessive rapidity of their flight, which, indeed, he was inclined to consider surpassed that of any other Insects. "The eye cannot follow them as they dart past; and the air, forcibly divided, gives out a deep sound louder than that produced by the humming-bird itself. If power of wing and rapidity of flight could place them in that rank, they should be considered the most highly organised of butterflies." It was probably to the genera _Pyrrhopyge_, _Erycides_, etc., that Mr. Wallace alluded in the above remarks. Although the Hesperiidae are not as a rule beautifully coloured, yet many of these higher forms are most tastefully ornamented; parts of the wings, wing-fringes, and even the bodies being set with bright but agreeable colours. We mention these facts because it is a fashion to attribute a lowly organisation to the family, and to place it as ancestral to other butterflies. Some of them have crepuscular habits, but this is also the case with a variety of other Rhopalocera in the tropics.

In their early stages the Skippers—so far as at present known—depart considerably from the majority of butterflies, inasmuch as they possess in both the larval and pupal instars habits of concealment and retirement. The caterpillars have the body nearly bare, thicker in the middle, the head free, and more or less notched above. They make much greater use of silk than other butterfly-larvae do, and draw together leaves to form caves for concealment, and even make webs and galleries. Thus the habits are almost those of the Tortricid moths.

{365}[Illustration: Fig. 185—Pupation of _Badamia exclamationis_. (After Dudgeon. _J. Bombay Soc._ x. 1895, p. 144). A, One side of the leaf-cradle, the other (nearest to the observer) being broken away; B, transverse section of entire cradle, _a_, The pupa; _b_, fastenings of perpendicular threads round pupa; _c_, cross thread retaining the leaf in cradle form; _d_, margins of the leaf; _e_, midrib of leaf.]

Pupation takes place under similar conditions; and it is interesting to find that Chapman considers that the pupa in several points of structure resembles that of the small moths. Not only does the larva draw together leaves or stalks to make a shelter for the pupa, but it frequently also forms a rudimentary cocoon. These arrangements are, however, very variable, and the accounts that have been given indicate that even the same species may exhibit some amount of variation in its pupation. Scudder considers that, in the North American Skippers, the cremaster is attached to a single Y-like thread. In other cases there is a silk pad on the leaf for the cremaster to hook on. An interesting account given by Mr. Dudgeon of the pupation of a common Indian Skipper, _Badamia exclamationis_, shows that this Insect exercises considerable ingenuity in the structure of the puparium, and also that the arrangements it adopts facilitate one of the acts of pupation most difficult for such pupae as suspend themselves, viz. the hooking the cremasters on to the pad above them. _Badamia_ uses a rolled-up leaf (Fig. 185); the edges of the leaf are fastened together by silk at _d_; from this spot there descends a thread which, when it reaches the pupa, _a_, forks so as to form an inverted Y, and is fastened to the leaf on either side; the two sides of the leaf are kept together by a cross thread, _cc_. Mr. Dudgeon was fortunate enough to observe the act of pupation, and saw that "although the anal prolegs of the larva were attached to a tuft or pad of silk in the usual way, and remained so until nearly the whole skin had been shuffled off, yet when the last segment had to be taken out, the pupa drew it entirely away from the skin and lifted it over the {366}empty skin, and by a series of contortions similar to those made by an Insect in depositing an egg, it soon re-attached its anal segment or cremaster to the web, throwing away the cast-off skin by wriggling its body about."

SERIES II. HETEROCERA. MOTHS.

Although Rhopalocera—if exclusion be made of the Hesperiidae—is probably a natural group, yet this is not the case with Heterocera. The only definition that can be given of Heterocera is the practical one that all Lepidoptera that are not butterflies are Heterocera. Numerous divisions of the Heterocera have been long current, but their limits have become more and more uncertain, so that at the present time no divisions of greater value than the family command a recognition at all general. This is not really a matter of reproach, for it arises from the desire to recognise only groups that are capable of satisfactory definition.

Several attempts have recently been made to form a rough forecast of the future classification of moths. Professor Comstock, struck by some peculiarities presented by the Hepialidae, Micropterygidae (and Eriocephalidae), recently proposed to separate them from all other Lepidoptera as a sub-order Jugatae. Comstock's discrimination in making this separation met with general approval. The character on which the group Jugatae is based is, however, comparatively trivial, and its possession is not sufficient, as pointed out by Packard,[230] to justify the close association of Hepialidae and Micropterygidae, which, in certain important respects, are the most dissimilar of moths. The characters possessed by the two families in common may be summarised by saying that the wings and wing-bearing segments remain in a low stage of development. In nearly all other characters the two families are widely different. Packard has therefore, while accepting Comstock's separation of the families in question, proposed a different combination. He considers that Eriocephalidae should be separated from all others as "Protolepidoptera" or "Lepidoptera Laciniata," while the whole of the other Lepidoptera, comprised under the term "Lepidoptera Haustellata," are divided into Palaeolepidoptera (consisting only of Micropterygidae) and Neolepidoptera, comprising all Lepidoptera {367}(inclusive of Hepialidae) except the Eriocephalidae and Micropterygidae. The question is rendered more difficult by the very close relations that exist between Micropterygidae and a sub-Order, Trichoptera, of Neuroptera. Dr. Chapman, by a sketch of the classification of pupae,[231] and Dyar, by one on larval stages,[232] have made contributions to the subject; but the knowledge of early stages and metamorphosis is so very imperfect that the last two memoirs can be considered only as preliminary sketches; as indeed seem to have been the wishes of the authors themselves.

Simultaneously with the works above alluded to, Mr. Meyrick has given[233] a new classification of the Order. We allude, in other pages, to various points in Mr. Meyrick's classification, which is made to appear more revolutionary than it really is, in consequence of the radical changes in nomenclature combined with it.

As regards the various aggregates of families that are widely known in literature by the names Bombyces, Sphinges, Noctuae, Geometres, Pyrales, we need only remark that they are still regarded as to some extent natural. Their various limits being the subject of discussion and at present undecided, the groups are made to appear more uncertain than is really the case. The group that has to suffer the greatest changes is the old Bombyces. This series comprises the great majority of those moths that have diurnal habits. In it there were also included several groups of moths the larvae of which feed in trunks of trees or in the stems of plants, such as Cossidae, that will doubtless prove to have but little connection with the forms with which they were formerly associated. These groups with aberrant habits are those that give rise to the greatest difficulties of the taxonomist.

The following key to the families of Heterocera is taken from Sir G. F. Hampson's recent work, _Fauna of British India—Moths_.[234] It includes nearly all the families at present recognised among the larger Lepidoptera; certain families[235] not mentioned in this key are alluded to in our subsequent remarks on the families:—

{368}Key to the Families of Moths[236]

N.B.—_This table is not simply dichotomic; three contrasted categories are used in the case of the primary divisions, A, B, C, and the secondary divisions, I, II, III_.

A. Fore wing with nervule 5 coming from the middle of the discocellulars, or nearer 6 than 4 (Categories I, II, III = 1-18).

I. Frenulum rudimentary. Fam. 38. EPICOPEIIDAE, see p. 418.

II. Frenulum absent (Categories 1-8).

1. Proboscis present, legs with spurs (Cat. 2-5).

2. Hind wing with nervule 8 remote from 7 (Cat. 3 and 4).

3. Fore wing with nervule 6 and 7 stalked Fam. 39. URANIIDAE, see p. 419.

4. Fore wing with nervules 6 and 7 not stalked Fam. 5. CERATOCAMPIDAE, see p. 375.

5. Hind wing with nervule 8 nearly touching 7 beyond end of cell Fam. 4. BRAHMAEIDAE, see p. 374.

6. Proboscis absent, legs without spurs (Cat. 7 and 8).

7. Hind wing with one internal nervure Fam. 3. SATURNIIDAE, see p. 372.

8. Hind wing with two or three internal nervures Fam. 6. BOMBYCIDAE, see p. 375.

III. Frenulum present (Cat. 9-18).

9. Antennae fusiform [spindle-shaped] Fam. 9. SPHINGIDAE, see p. 380.

10. Antennae not fusiform (Cat. 11-18).

11. Proboscis absent Fam. 7. EUPTEROTIDAE, see p. 376.

12. Proboscis present (Cat. 13-18).

13. Hind wing with nervule 8 curved and almost touching 7 after end of cell; nervure 1a reaching anal angle Fam. 12. CYMATOPHORIDAE, see p. 386.

14. Hind wing with nervule 8 remote from 7 after end of cell (Cat. 15-18).

15. Tarsi as short as tibia, hairy; stoutly built moths Fam. 11. NOTODONTIDAE,[237] see p. 383.

16. Tarsi long and naked; slightly built moths (Cat. 17 and 18)

17. Fore wing with nervule 7 remote from 8, and generally stalked with 6 Fam. 40. EPIPLEMIDAE, see p. 420.

18. Fore wing with nervule 7 given off from 8; hind wing with nervure 1a short or absent Fam. 36. GEOMETRIDAE, see p. 411.

B. Fore wing with nervule 5 coming from lower angle of cell or nearer 4{369} than 6 [see figures 161 and 162, pp. 318, 319] (Categories 19-58).

19. Hind wing with more than 8 nervules (Cat. 20, 21).

20. Proboscis absent, no mandibles nor ligula; size not very small Fam. 23. HEPIALIDAE, see p. 396.

21. Mandibles, long palpi and ligula present; size very small Fam. 47. MICROPTERYGIDAE, see p. 435.

22. Hind wing with not more than 8 nervules (Cat. 23-58).

23. Hind wing with nervule 8 remote from 7 after origin of nervules 6 and 7 (Cat. 24-51).

24. Frenulum absent (Cat. 25-29).

25. Hind wing with one internal nervure; nervule 8 with a precostal spur, Fam. 31. PTEROTHYSANIDAE, see p. 406.

26. Hind wing with two internal nervures (Cat. 27 and 28).

27. Hind wing with a bar between nervules 7 and 8 near the base; nervure 1a directed to middle of inner margin Fam. 30. ENDROMIDAE, see p. 406.

28. Hind wing with no bar between nervules 7 and 8; nervure 1a directed to anal angle Fam. 29. LASIOCAMPIDAE, see p. 405.

29. Hind wing with three internal nervures Fam. 21. ARBELIDAE, see p. 396.

30. Frenulum present (Cat. 31-51).

31. Hind wing with nervule 8 aborted Fam. 15. SYNTOMIDAE, see p. 388.

32. Hind wing with nervule 8 present (Cat. 33-51).

33. Antennae knobbed, Fam. 1. CASTNIIDAE, see p. 371.

34. Antennae filiform, or (rarely) dilated a little towards the tip (Cat. 35-51).

35. Fore wing with nervure 1c present (Cat. 36-43).

36. Hind wing with nervule 8 free from the base or connected with 7 by a bar (Cat. 37-42).

37. Proboscis present Fam. 16. ZYGAENIDAE, see p. 390.

38. Proboscis absent (Cat. 39-42).

39. Palpi rarely absent; ♀ winged; larvae wood-borers Fam. 20. COSSIDAE, see p. 395.

40. Palpi absent; ♀ apterous (Cat. 41, 42).

41. ♀ rarely with legs; ♀ and larvae case-dwellers Fam. 19. PSYCHIDAE, see p. 392.

42. ♀ and larvae free[238] Fam. 18. HETEROGYNIDAE, see p. 392.

43. Hind wing with nervule 8 {370} anastomosing shortly with 7 Fam. 26. LIMACODIDAE, see. p. 401.

44. Fore wing with nervure 1c absent (Cat. 45-51).

45. Hind wing with nervule 8 rising out of 7 Fam. 34. ARCTIIDAE, see p. 408.

46. Hind wing with nervule 8 connected with 7 by a bar, or touching it near middle of cell (Cat. 47, 48).

47. Palpi with the third joint naked and reaching far above vertex of head; proboscis present Fam. 33. HYPSIDAE, see p. 408.

48. Palpi not reaching above vertex of head; proboscis absent or very minute Fam. 32. LYMANTRIIDAE, see p. 406.

49. Hind wing with nervule 8 anastomosing shortly with 7 near the base; proboscis well developed (Cat. 50, 51).

50. Antennae more or less thick towards tip Fam. 35. AGARISTIDAE, see p. 410.

51. Antennae filiform Fam. 37. NOCTUIDAE, see p. 414.

52. Hind wing with nervule 8 curved and nearly or quite touching nervure 7, or anastomosing with it after origin of nervules 6 and 7 (Cat. 53-58).

53. Hind wing with nervure 1c absent (Cat. 54-57).

54. Hind wing with nervule 8 with a precostal spur Fam. 24. CALLIDULIDAE, see p. 400.

55. Hind wing with nervule 8 with no precostal spur (Cat. 56, 57).

56. Hind wing with nervure 1a absent or very short Fam. 25. DREPANIDAE, see p. 400.

57. Hind wing with nervure 1a almost or quite reaching anal angle Fam. 28. THYRIDIDAE, see p. 404.

58. Hind wing with nervure 1c present Fam. 41. PYRALIDAE, see p. 420.

C. Fore wing with 4 nervules arising from the cell at almost even distances apart (Cat. 59-66).

59. Wings not divided into plumes (Cat. 60-63).

60. Hind wing with nervule 8 coincident with 7 Fam. 13. SESIIDAE, see p. 386.

61. Hind wing with nervule 8 free (Cat. 62, 63).

62. Fore wing with nervure 1b simple or with a very minute fork at base Fam. 14. TINAEGERIIDAE, see p. 387.

63. Fore wing with nervure 1a forming a large fork with 1b at base Fam. 45. TINEIDAE, see p. 428.

64. Wings divided into plumes (Cat. 65, 66). {371}

65. Fore wing divided into at most two, hind wing into three plumes Fam. 42. PTEROPHORIDAE, see p. 426.

66. Fore wing and hind wing each divided into three plumes Fam. 43. ALUCITIDAE (= ORNEODIDAE), see p. 426.

FAM. 1. CASTNIIDAE.—_The Insects of this family combine to a large extent the characters of butterflies and moths. The antennae are knobbed or hooked at the tip, there is a large precostal area to the hind wing. The nervules of the front wing are complex and anastomose so as to form one or more accessory cells_ (Fig. 162). This important, but not extensive, family consists chiefly of forms found in tropical America and Australia. The diversity of size, form and appearance is very great, and it is probable that the members of the family will be separated; indeed, taxonomists are by no means in agreement as to the limits of the family. The Castniidae are diurnal Insects, and the North American genus _Megathymus_ is by many considered to belong to the Rhopalocera. _Euschemon rafflesiae_ (Fig. 186) is extremely like a large Skipper with long antennae, but has a well-marked frenulum. The members of the Australian genus _Synemon_ are much smaller, but they also look like Skippers. Their habits are very like those of the Hesperiidae; they flit about in the hot sunshine, and when settling after their brief flights, the fore wings are spread out at right angles to the body, so as to display the more gaily coloured hind wings; at night, or in cloudy weather, the Insect rests on blades of grass with the wings erect, meeting vertically over the back, like a butterfly. _Hecatesia_, another Australian genus, is now usually assigned to _Agaristidae_; its members look like moths. The male of _H. fenestrata_ is provided with a sound-producing organ similar to that of the Agaristid genus _Aegocera_.

[Illustration: Fig. 186—_Euschemon rafflesiae._ Australia. (After Doubleday.)]

The _Castnia_ of South America are many of them like {372}Nymphalid butterflies, but exhibit great diversity, and resemble butterflies of several different divisions of the family.[239]

The species are apparently great, lovers of heat and can tolerate a very dry atmosphere.[240] The transformations of very few have been observed; so far as is known the larvae feed in stems; and somewhat resemble those of Goat-moths or Leopard-moths (Cossidae); the caterpillar of _C. therapon_ lives in the stems of Brazilian orchids, and as a consequence has been brought to Europe, and the moth there disclosed. The pupae are in general structure of the incomplete character, and have transverse rows of spines, as is the case with other moths of different families, but having larvae with similar habits.[241] _Castnia eudesmia_ forms a large cocoon of fragments of vegetable matter knitted together with silk. These Insects are rare in collections; they do not ever appear in numbers, and are generally very difficult to capture.

FAM. 2. NEOCASTNIIDAE.—The Oriental genus _Tascina_, formerly placed in Castniidae has recently been separated by Sir G. Hampson and associated with _Neocastnia nicevillei_, from East India, to form this family. These Insects have the appearance of Nymphalid butterflies. They differ from Castniidae by the want of a proboscis.

FAM. 3. SATURNIIDAE.—This is a large and varied assemblage of moths; the larvae construct cocoons; the products of several species being used as silk. These moths have no frenulum and no proboscis. The hind wings have a very large shoulder, so that the anterior margin or costa stretches far forward beneath the front wing, as it does in butterflies. The antennae of the males are strongly bipectinated and frequently attain a magnificent development. The family includes some of the largest and most remarkable forms of the Insect-world, _Coscinocera hercules_, inhabiting North Australia, is a huge moth which, with its expanded wings and the long tails thereof, covers a space of about 70 square inches. One of the striking features of the family is the occurrence in numerous forms of remarkable transparent spaces on the wings; these window-like areas usually occur in the middle of the wing and form a most remarkable contrast to the rest of the surface, which is very densely {373}scaled. In _Attacus_ these attain a large size. In other species, such as the South African _Ludia delegorguei_, there is a small letter-like, or symboliform, transparent mark towards the tip of each front wing. We have at present no clue to the nature or importance of these remarkable markings. In the genus _Automeris_, and in other forms, instead of transparent spaces there are large and staring ocellate marks or eyes, which are concealed when the Insect is reposing. In _Arceina_, _Copiopteryx_, _Eudaemonia_ and others, the hind wings are prolonged into very long tails, perhaps exceeding in length those of any other moths.

[Illustration: Fig. 187—Larva of _Attacus atlas_, India. A, at end of 1st instar, profile; B, 4th instar, dorsal view; C, full-grown larva, in repose. (After Poujade.)]

The cocoons are exceedingly various, ranging from a slight open network to a dense elaborate structure arranged as in our Emperor moth; in this latter case an opening is left by the larva for its exit after it has become a moth, but by an ingenious, chevaux-de-frise work, this opening is closed against external enemies, though the structure offers no resistance at all to the escape of the moth. Fabre has recorded some observations and experiments which seem to show that the instinct predominating over the formation of the cocoon is not cognoscent. The Insect, if interfered with, displays a profound stupidity. Its method is blind perseverance in the customary.[242] The cocoon of Saturniidae is more often continuous, _i.e._ entirely closed. Packard says that {374}_Actias luna_ effects its escape by cutting through the strong cocoon with an instrument situate at the base of the front wing. Other species were examined and were found to possess the instrument; but Packard is convinced that the majority of the species possessing the instrument do not use it, but escape by emitting a fluid that softens the cocoon and enables the moth to push itself through.[243] The cocoons of the species of _Ceranchia_ have a beautiful appearance, like masses of filagree-work in silver. The pupa in _Ceranchia_ is very peculiar, being terminated by a long, spine-like process. In _Loepa newara_ the cocoon is of a green colour and suspended by a stalk; looking like the pod, or pitcher, of a plant. The silk of the Saturniidae is usually coarse, and is known as Tusser or Tussore[244] silk.

The larvae of this family are as remarkable as the imagos, being furnished with spine-bearing tubercles or warts, or long fleshy processes; the colours are frequently beautiful. The caterpillar of _Attacus atlas_ (Fig. 187) is pale olive-green and lavender, and has a peculiar, conspicuous, red mark on each flank close to the clasper.

About seventy genera and several hundred species are already known of this interesting family. They are widely distributed on the globe, though there are but few in Australia. Our only British species, the Emperor moth, _Saturnia pavonia_, is by no means rare, and its larva is a beautiful object; bright green with conspicuous tubercles of a rosy, or yellow, colour. It affects an unusual variety of food-plants, sloe and heather being favourites; the writer has found it at Wicken flourishing on the leaves of the yellow water-lily. Although the Emperor moth is one of the largest of our native Lepidopterous Insects, it is one of the smallest of the Saturniidae.

The family Hemileucidae of Packard is included at present in Saturniidae.

FAM. 4. BRAHMAEIDAE.—The species forming the genus _Brahmaea_ have been placed in various families, and are now treated by Hampson as a family apart, distinguished from Saturniidae by the presence of a proboscis. They are magnificent, large moths, of sombre colours, but with complex patterns on the wings, looking as if intended as designs for {375}upholstery. About fifteen species are recognised; the geographical distribution is remarkable; consisting of a comparatively narrow belt extending across the Old World from Japan to West Africa, including Asia Minor and the shores of the Caspian Sea. Little has been recorded as to the life-histories of these Insects. The larva is said to have the second and third segments swollen and armed with a pair of lateral spines projecting forwards. A cocoon is not formed.

FAM. 5. CERATOCAMPIDAE.—This is a small family. They are fine moths peculiar to the New World, and known principally by scattered notices in the works of North American entomologists. Seven genera and about sixty species are known. The chief genus is _Citheronia_. Some of the larvae are remarkable, being armed with large and complex spines. A cocoon is not formed.

FAM. 6. BOMBYCIDAE.—In entomological literature this name has a very uncertain meaning, as it has been applied to diverse groups; even at present the name is frequently used for the Lasiocampidae. We apply it to the inconsiderable family of true silkworm moths. They are comparatively small and uninteresting Insects in both the larval and imaginal instars; but the cocoons formed by the well-known silkworm are of great value, and some other species form similar structures that are of more or less value for commercial purposes. The silkworm has been domesticated for an enormous period, and is consequently now very widely spread over the earth's surface; opinions differ as to its real home, some thinking it came originally from Northern China, while others believe Bengal to have been its native habitat. The silkworm is properly called _Bombyx mori_, but perhaps it is as often styled _Sericaria mori_. Besides being of so great a value in commerce, this Insect has become an important object of investigation as to anatomy, physiology and development. Its domestication has probably been accompanied by a certain amount of change in habits and instincts, the creature having apparently lost its appreciation of freedom and its power of flight; it is also said to be helpless in certain respects when placed on trees in the larval state; but the importance of these points has been perhaps somewhat exaggerated.[245]

Although the family Bombycidae is very widely distributed in the warmer regions of the world, it includes only 15 or 20 {376}genera, and none of them have many species. The Mustiliidae of some entomologists are included here. Like the Saturniidae, the Bombycidae are destitute of proboscis and of frenulum to the wings, but they possess two or three internal nervures on the hind wing instead of the single one existing in Saturniidae.

FAM. 7. EUPTEROTIDAE (Striphnopterygidae of Aurivillius).—This family has only recently been separated from Lasiocampidae; its members, however, possess a frenulum; while none is present in the larger family mentioned. Its limits are still uncertain, but it includes several extremely interesting forms. The larvae of the European processionary moth, _Cnethocampa processionea_, are social in habits; they sometimes occur in very large numbers, and march in columns of peculiar form, each band being headed by a leader in front, and the column gradually becoming broader. It is thought that the leader spins a thread as he goes on, and that the lateral leaders of the succeeding files fasten the threads they spin to that of the first individual, and in this way all are brought into unison. The hairs of these caterpillars are abundant, and produce great irritation to the skin and mucous membrane of any one unlucky enough to come into too close contact with the creatures. This property is, however, not confined to the hairs of the processionary moths, but is shared to a greater or less extent by the hairs of various other caterpillars of this division of Lepidoptera. In some cases the irritation is believed to be due to the form of the hair or spine, which may be barbed or otherwise peculiar in form. It is also thought that in some cases a poisonous liquid is contained in the spine.

The larvae of other forms have the habit of forming dense webs, more or less baglike, for common habitation by a great number of caterpillars, and they afterwards spin their cocoons inside these receptacles. This has been ascertained to occur in the case of several species of the genus _Anaphe_, as has been described and illustrated by Dr. Fischer,[246] Lord Walsingham,[247] and Dr. Holland.[248] The structures are said to be conspicuous objects on trees in some parts of Africa. The common dwelling of this kind formed by the caterpillars of _Hypsoides radama_ in Madagascar is said to be several feet in length; but the structures of most of the other species are of much smaller size.

{377}The larvae of the South American genus _Palustra_, though hairy like other Eupterotid caterpillars, are aquatic in their habits, and swim by coiling themselves and making movements of extension; the hair on the back is in the form of dense brushes, but at the sides of the body it is longer and more remote; when the creatures come to the surface—which is but rarely—the dorsal brushes are quite dry, while the lateral hairs are wet. The stigmata are extremely small, and the mode of respiration is not fully known. It was noticed that when taken out of the water, and walking in the open air, these caterpillars have but little power of maintaining their equilibrium. They pupate beneath the water in a singular manner: a first one having formed its cocoon, others come successively and add theirs to it so as to form a mass.[249] Another species of _Palustra_, _P. burmeisteri_, Berg,[250] is also believed to breathe by means of air entangled in its long clothing; it comes to the surface occasionally, to renew the supply; the hairs of the shorter brushes are each swollen at the extremity, but whether this may be in connexion with respiration is not known. This species pupates out of the water, between the leaves of plants.

_Dirphia tarquinia_ is remarkable on account of the great difference of colour and appearance in the two sexes. In the Australian genus _Marane_ the abdomen is densely tufted at the extremity with hair of a different colour.

FAM. 8. PEROPHORIDAE.—The moths of the genus _Perophora_ have for long been an enigma to systematists, and have been placed as abnormal members of Psychidae or of Drepanidae, but Packard now treats them as a distinct family. The larvae display no signs of any social instincts, but, on the contrary, each one forms a little dwelling for itself. Some twenty species of _Perophora_ are now known; they inhabit a large part of the New World, extending from Minnesota to Buenos Aires. The habits of _P. melsheimeri_ have been described by Harris, Packard[251] and Newman, and those of _P. batesi_ by Newman.[252] The larva is very peculiar; there is a flexible pair of appendages on the {378}head, the use of which is unknown;[253] they arise by slender stalks behind and above the eyes, are about as long as the head, and are easily broken off. After hatching, the young larva, when it begins to feed, fastens two leaves together with silk threads, and so feeds after the fashion of a Tortricid, rather than a case-making, larva. Subsequently, however, the caterpillar entirely detaches two pieces of leaves and fastens them together at the edges, thus constructing a case that it lives in, and carries about; it can readily leave the case and afterwards return to it. When at rest, the larva relieves itself from the effort of supporting this case by the device of fastening it to a leaf with a few silken threads; when the creature wished to start again, "it came out and bit off these threads close to the case." Subsequently it changes inside the case to a pupa armed with transverse rows of teeth, like so many other pupae that are capable of a certain amount of movement. The larva is of broad, short, peculiar form, and is said to be very bold in defending itself when attacked. The moth is somewhat like the silkworm moth, though of a more tawny colour. Newman does not allude to any cephalic appendages as existing in the larva of _P. batesi_. If we accept the eggs figured and described by Snellen,[254] as those of _P. batesi_, it is possible that this Insect possesses a peculiar mode of oviposition, the eggs being placed one on the other, so as to form an outstanding string; but we think this example probably abnormal; the mode is not shared by _P. melsheimeri_. The genus _Lacosoma_ is considered by Packard to be an ally of _Perophora_. The caterpillar of _L. chiridota_ doubles a leaf at the mid-rib and fastens the two edges together, thus forming an unsymmetrical case. Many larvae of Microlepidoptera do something like this, but the _Lacosoma_ cuts off the habitation thus formed and carries it about. Packard says it may have descended from ancestors with ordinary habits and that certain peculiar obsolete markings on the body of the caterpillar may be indications of this.[255]

{379}[Illustration: Fig. 188—Larvae of Hammock-moth, _Perophora sanguinolenta_, projecting from their Hammocks, built from their own excrement. South America. (After Jones.)]

The Argentinian Insect _Mamillo curtisea_[256] is also probably an ally of _Lacosoma_. The caterpillar of this moth spins a dwelling for itself, and is remarkable from the bright colour of the thoracic segments, the following somites being colourless; the head bears a pair of large processes, quite different from those figured by Harris. The moth itself is very Geometrid-like in colour and form. This species is now assigned to _Perophora_, but it seems to be very doubtful whether many of the species placed in this genus really belong to it. The diversity of habits and instincts evinced by these moths of exceptional modes of life, but considered to be closely allied, is very interesting. The most remarkable of all is the Hammock-moth, _Perophora sanguinolenta_, of the centre of South America, the larva of which constructs its portable habitations out of its own {380}excrement, which is of peculiar form, specially suitable for the purpose. The caterpillar, when wishing to enlarge its case, builds it up from excrement "flattened at the sides, so as to adapt it for building purposes."[257]

[Illustration: Fig. 189.—Antennae of Sphingidae. A, One joint of antenna of _Choerocampa elpenor_ ♂, enlarged; B, three joints of antenna of _Sphinx ligustri_, seen from one side, and enlarged.]

FAM. 9. SPHINGIDAE (_Hawk-moths_).—A very important family of moths of large or moderate size. They have a proboscis which is frequently very long; there is a frenulum; the body is stouter than in most other Lepidoptera, and the wings are of small superficies in comparison with it; the antennae are somewhat peculiar, having a thick, solid appearance, pointed at the tip. This is usually somewhat hooked, and bears a few hairs. In the males the antennae are formed in a manner specially characteristic of the family. In section, each joint shows a chitinous process on the under side (Fig. 189, A), forming with that of the other joints a continuous ridge, and on each side of this ridge there exists a series of short, delicate "cilia" arranged in a very beautiful manner (Fig. 189, B). This structure, with some modifications, appears to be usually present in the family; it attains a very perfect development in cases where the tips of two rows of cilia bend towards one another, meeting so as to form an arched cavity. This structure is different from what occurs in the males of other families of Lepidoptera, for though cilia are very common, they are usually placed either on two projections from the body of the antennae (instead of on the two sides of a single projection), or there is but a single whorl, or set, of them on each joint (_Catocala_, etc.). The front wings are usually pointed at the tip, and are long in proportion to their width; but in the Smerinthini they are of different form, with the outer margin scalloped; the hind wings are remarkably small; the abdomen is frequently pointed, but in the Macroglossini, or Humming-bird hawk-moths, it is furnished at the {381}tip with a tuft, or with two tufts, of dense, long scales, capable of expansion.

The larvae are remarkable for their colours and form. The anterior segments are attenuated, but are capable of great retraction, so that in repose (Fig. 190, A) this shape is concealed by the curious attitudes that are assumed. There is in nearly all cases a conspicuous horn on the eleventh segment, and the body at the extremity behind the horn is so much modified that the terminal two segments look like little more than a pair of large claspers. In the Choerocampini, the thoracic segments are retractile, and can be withdrawn into the more or less inflated fourth segment, and give the creature somewhat the appearance of a miniature hooded snake. The larvae of Sphingidae do not bear any conspicuous hairs—except during the first instar. They do not spin cocoons, but bury themselves in the earth. The pupa is remarkable from the deep cleft that exists to admit air to the first spiracle, and for a deep depression on each side of the anterior part of abdominal segments 5-7; in some cases the proboscis projects on the breast somewhat like the handle of a pitcher.

[Illustration: Fig. 190—Larva of the Poplar Hawk-moth, _Smerinthus populi_. × 1. A, in repose; B, in movement.]

A great deal has been written on the colours, markings, and attitudes of Sphingid larvae, and many interesting facts have been brought to light. We may refer the reader to the writings of Weismann[258] and Poulton,[259] without, however, recommending him to place an implicit confidence in their somewhat metaphysical disquisitions; for the views there shadowed will {382}necessarily became much modified with the advance of exact knowledge. It is certain that the position assumed by the same individual varies much according to age, and to the interval since the last moult; sometimes the attitude is much more remarkable than that shown in Figure 190, A, for the anterior segments are held erect, as well as contracted, the front part of the body being curled, and the Insect supported by the claspers and two pairs only of the abdominal feet. There is, too, a considerable difference in colour before and after an ecdysis. Piepers, who has had a long experience among Sphingid larvae in Java, considers that much of what has been written as to the protective value of their colours and attitudes, is mere fancy, and wild generalisation.[260]

Sphingidae have been recorded as capable of producing sounds in the larval and pupal, as well as in the perfect, instars; but the method in which this is done has not been ascertained, except in the case of the imago of the Death's-head moth, which is well known to emit a very audible cry when not on the wing; in this case it is highly probable that the method is the friction of the palpi against the proboscis, as stated by Réaumur and Landois; the inner face of the palp is said to be marked in this case with fine ridges or striae.

[Illustration: Fig. 191—_Cocytia durvillii._ New Guinea. (After Boisduval.)]

FAM. 10. COCYTIIDAE.—A single genus constitutes this family, and there are only three or four species known; they come from the region of New Guinea, whence the first was brought by D'Urville nearly a hundred years ago. They are still amongst {383}the rarest of Insects. Nothing is known as to their life-histories. In appearance they somewhat remind us of the Bee-hawk moths and Zygaenidae. Butler says[261] the family is characterised by the palpi, which differ much in the two sexes, and by the antennae resembling those of Castniidae or Hesperiidae. The form, transparency, and coloration of the wings reminds one vividly of the Sphingid genus _Hemaris_; the nervuration is somewhat like that of _Hemaris_, but has certain features of Zygaenidae. Butler places the family between Agaristidae and Zygaenidae.

[Illustration: Fig. 192—_Cerura vinula_ (Puss-moth) caterpillar. A, Moulting; B, the same individual a few hours after the moult.]

FAM. 11. NOTODONTIDAE (_Prominents_, _Puss-moths_, etc.).—This is one of the most extensive of the families of Bombyces; it consists in larger part of obscure-coloured moths, somewhat like the ordinary Noctuidae of temperate regions; to which family the Notodonts are indeed considered to be very closely allied. The family contains, however, some very remarkable forms. _Tarsolepis_ has an elongate body, terminated (in the female of _T. fulgurifera_) by a very conspicuous tuft of enormously long, battledore scales; while in the male of _T. sommeri_ the hind legs are provided with an appendage of beautiful, roseate hairs. A few of the larger kinds bear a considerable resemblance in form and proportions to the Sphingidae. Some of the larvae are most interesting objects; the Puss-moth caterpillar, the Lobster, and the Dragon larvae are of such strange forms that they have already interested several generations of observers. The Puss-moth is common in the southern half of England; its caterpillar (Fig. 192) has, instead of the claspers, a pair of tubes in which are concealed {384}two long, flexible whips, capable of being thrust out, and withdrawn, with rapidity. The structure and the mode of action of these flagella have been well elucidated by Professor Poulton.[262] The flagella are to be considered as actual prolongations of the receptacle in which each is placed, though they are of very different texture therefrom; they are everted by blood-pressure and drawn in by muscular action; this latter function is very perfectly accomplished, the amount of relaxation and contraction of the muscle being very great. It has been maintained that the whips have arisen as arms of protection against the attacks of Ichneumon flies; observation shows, however, that the proportion of these "protected" Insects destroyed by enemies of this sort is quite as large as it is in the case of forms that are not so protected. The Puss-moth larva is also believed to be protected by terrifying attitudes,[263] as well as by ejection (like so many other larvae and insects generally) of fluid. There is no reason for believing that these larvae are less eaten than others, and consequently a further hypothesis has been proposed, to the effect that if they had not acquired these means of defence they would have been exterminated altogether. This supposition is considered to account for their acquiring the defence by means of natural selection; realising the dictum of D. O'Phace, Esq.—

Some flossifers think that a fakkilty's granted, The minnit it's proved to be thoroughly wanted.

When the Puss-moth caterpillar is full grown it spins a peculiar cocoon of a solid and impervious nature, which it manages to make look very like the spots, crevices, or other places amongst which it is located; in this prison the creature remains for nine or ten months—by far the larger part of its existence. When it has changed to a moth it has to escape from the cell in which it so effectually confined itself. This is effected by the cocoon being thinner in front of the head of the moth, and by the emission from the alimentary canal of a fluid that softens the cocoon at the spot alluded to. Mr. Latter has ascertained[264] that this fluid is strongly alkaline, and contains potassium hydroxide. The front of the head of the moth is provided with a shield, consisting of a portion of the pupa shell, which enables the moth to {385}push through in safety, and at the same time protects the head from the emitted fluid. Figure 192 shows the great change that occurs in the period of a few hours in the size of the head of the larva, as well as in that of the spiracles: in A the old spiracles are seen surrounded by the much larger new orifices, which are at the moment of moulting quite visible through the skin that is about to be cast off.

The caterpillar of the Lobster-moth, _Stauropus fagi_, is more remarkable than that of the Puss-moth, but is unfortunately very rare. It has remarkably long thoracic legs, the abdomen is swollen at the tip, and instead of the terminal claspers has two long slender processes. The effect of these peculiarities is greatly enhanced by the extraordinary attitude assumed by the caterpillar, which holds the first five segments erect, with the second and third pairs of thoracic legs outstretched; the swollen terminal segment is also held erect. Hermann Müller states[265] that when seen from the front this caterpillar looks like a spider, and also that when alarmed it moves the long legs after the fashion of an Arachnid. He believes that it is thus effectually protected from the attacks of Ichneumons. Birchall says[266] that the young larva, when at rest, closely resembles, in colour and outline, one of the twigs of beech with unopened buds, on which it frequently stations itself; and that, when feeding, its likeness to a great earwig or to a _Staphylinus_ is very striking. Others say that this caterpillar resembles a dead and crumpled beech leaf.

The larva of _Hybocampa milhauseri_—the Dragon of old Sepp—is highly remarkable. When young it has grand lateral horns in front, and a dorsal row; as it grows the lateral horns disappear. Dr. Chapman says[267] that he could not understand at first why any larva should have such remarkable angular outlines, curiously conspicuous corners and humps. But he afterwards found that the creature exactly resembled a curled oak leaf, eaten and abandoned by a _Tortrix_ larva. This caterpillar also constructs an elaborate cocoon from which the moth escapes by an operation performed by the pupa, which is provided with two hard spines, called by Dr. Chapman sardine-openers. "By a lateral rotatory movement of the pupa, which obtains its fulcrum {386}from the tightness with which it is grasped by the cocoon, it traverses over and over again" the same part of the cocoon till it is cut through; at the same time the spines act as guides to a fluid which is emitted so as to soften the part that has to be sundered.

Though many other larvae of Notodontidae are of most curious form and assume remarkable attitudes, yet this is not the case with all, and some are quite ordinary and like the caterpillars of common Noctuidae. This is the case with the species _Rhegmatophila alpina_ we have selected to illustrate the metamorphosis of the Order (Fig. 157). Those who wish to form an idea of the variety of larval forms in this family will do well to refer to Packard's beautiful volume on the North American forms.[268] The family has a very wide distribution, but is absent from New Zealand and Polynesia, and appears to be but poorly represented in Australia. In Britain we have about two dozen species.

FAM. 12. CYMATOPHORIDAE.—A small family of nocturnal moths that connect the Bombyces with the Noctuids; they are usually associated with the latter, but are widely separated in Hampson's arrangement because of a slight difference of nervuration, nervule 5 being nearer to 6 than to 4, whereas in Noctuidae the reverse is the case. The Insects, however, in certain respects approach the Notodontidae, and are of interest if only as showing that the linear sequences we adopt in books are necessarily conventional, and to some extent deceptive. We have three genera in Britain; our pretty Peach-blossom, _Thyatira batis_, and the very different Buff-arches, _T. derasa_, being among them. Meyrick denies any connexion of this group with Noctuidae, and in his nomenclature _Cymatophora_ becomes _Polyploca_, and the family, consequently, Polyplocidae.

FAM. 13. SESIIDAE or AEGERIIDAE (_Clear-wings_).—A family of comparatively small extent; its members have frequently one or both pairs of wings in large part free from scales, the tip of the body tufted, the hind legs of one sex peculiar. The size is usually small, but in the largest forms the measurement may be but little less than two inches across the expanded wings. The pupa is of the kind classed as "incompletae" by Chapman, the appendages not being firmly glued to the body, and much {387}mobility existing; an "eye-collar" is present, and the segments of the abdomen are armed with series of teeth. The larva is a concealed feeder, nearly naked and colourless, but with the legs normal in number—three thoracic, four abdominal pairs of feet, and the terminal claspers; these are sometimes but poorly developed; the larvae have a greater or less resemblance to those of Longicorn beetles, the habits of which they share. The family was formerly associated with the Sphingidae, with which it has no true relationship; it is more closely allied to the Tineidae. Some of the species have a certain resemblance to Hymenoptera, which is probably in most, if not in all cases merely incidental. The proper position of the family was pointed out by Butler,[269] but he did not distinguish it from Tinaegeriidae. Meyrick calls the family Aegeriadae, and places it in his series Tineina.

[Illustration: Fig. 193—_Oedematopoda princeps._ Africa. (After Walsingham.)]

We have two genera of these Clear-wings in Britain. They are _Trochilium_ (called variously _Sesia_, _Sphecia_, and _Aegeria_), with two species of comparatively large size, and _Sesia_ (called variously _Trochilium_ and _Aegeria_), with nearly a dozen species of smaller size. A third genus, _Sciapteron_, is doubtfully native with us. They are much prized by collectors on account of the rarity of the Insects and their great difference in appearance from our other native Lepidoptera.

FAM. 14. TINAEGERIIDAE. This is one of the least known of the families of Lepidoptera, and has only recently been distinguished from Sesiidae. It is entirely exotic, and our knowledge of it is principally due to Lord Walsingham.[270] Nothing is known as to the life-histories, except that it has been stated by Stainton that a larva feeds in webs on shoots of a shrub of the genus _Clerodendron_. The family is widely distributed, but its metropolis will probably prove to be the tropics of Africa. It is of considerable interest as showing that the Sesiidae really {388}belong to the Tineid series of moths. The species we figure (Fig. 193) has a character otherwise peculiar to Sesiidae in the wings being inserted on the thorax remote from the head—a feature we do not find in the Tineidae proper; while on the other hand it has the long wing-fringes, and the shape of the wings that are characteristic of Tineidae. It is worth mentioning that though these Insects are of excessive rarity and very peculiar, there exists in the Solomon Islands[271] a species distinct from, though at first sight excessively similar to, the S. African one we figure.

FAM. 15. SYNTOMIDAE.—This family has usually been associated with the Zygaenidae. It includes a large number of moths having, as a rule, in external appearance little to distinguish them from the family named. Many of them are of gaudy colours, and probably of diurnal, but somewhat sedentary, habits. The wings are less ample than usual, the hind pair frequently very small, so that the Insects have somewhat the proportions of Hymenoptera. In some cases the resemblance is made more remarkable by the fact that the wings are transparent and bare of scales, or have scales only at the margins, so as to be like the wings of Hymenoptera. Not less remarkable is the fact that these Insects use the body itself for the purposes of adornment or display; thus adopting a system prevalent in the Hymenoptera, rather than that of their own Order, where the rule is that the wings are more ornamented than the body. In many cases the shape of the body is so very different from the normal that the disposition of the organs of life in the interior of the body must be materially affected. In some genera, such as _Andrenimorpha_, the form, colour and attitude of the body and some of the limbs are plainly similar to Hymenoptera. These Insects have a highly-developed frenulum, retinaculum, and proboscis; bipectinate antennae in the male, a complex organ at the base of the abdomen on each side, and are in fact highly-developed forms, except perhaps as regards the structures in connexion with flight.

Unfortunately little or nothing is known as to the habits and metamorphoses of these extraordinary creatures, but it is no doubt to them Seitz referred in saying, "How far one may be deceived by appearances of a mimetic nature can only be comprehended by visiting the tropics; in this part of the world {389}[Europe] one is prepared by knowledge gained from books for the appearance _Sesia_ presents. Had one no knowledge of this sort as to Sesiidae he would actually in the field [in Brazil] overlook dozens of these little creatures without being aware of his deception. The surprise at finding a quite different being in the net from what one believes he has caught occurs daily in Brazil, so rich in Lepidoptera."[272] The same intelligent observer says[273] that a species of _Macrocneme_ was observed by him to be exactly like one of the blue wasps of the genus _Pepsis_.

One remarkable point in these Hymenopteroid Syntomids is their complete dissimilarity from their immediate allies. They resemble very different Hymenoptera; and not only stinging Hymenoptera; the Sessiliventres have a large share of their attentions; the numerous species of _Dycladia_ partaking the appearance of the South American Sawflies in a wonderful manner. Bees, Wasps of the most different kinds, and a variety of Sawflies are beautifully paralleled, if one may use such an expression, by these Syntomids. That shown in Fig. 194 has the abdomen formed like that of a Petiolate Hymenopteron; the base of this part, moreover, resembles in a remarkable manner the "median segment" of that Order. The constriction is, however, placed not at the base of the abdomen but beyond the second segment. Thus the structure is not morphologically similar to that of the Hymenoptera, for the median segment of Aculeate Hymenoptera consists of only one abdominal segment, while in this moth the corresponding part is formed of two segments. Though anatomically inexact, the resemblance is, as to proportions, correct; and those who delight in the use of the imagination will see that had the moth used only one segment for the imitation, the result would have been less successful owing to insufficient size. In his very interesting account of some Brazilian Syntomids,[274] Seitz describes a species of _Trichura_ provided with a long appendage that is held straight backwards during life; and he informs us that this creature resembles a female Ichneumon, the long process looking like the elongate ovipositor of the Hymenopteron. Possibly the species from Demerara we figure may resemble an Ichneumon we are not acquainted with, though its colour and form rather suggest a likeness to an Aculeate. {390}This case of resemblance is of the most noteworthy character, for an appendage of this kind in a Lepidopterous Insect is without parallel, and is almost equivalent to the production of a new structure. An interesting feature of the case is that Ichneumonidae do not sting, and there is no evident reason why the enemies of the moth should be particularly afraid of an ovipositor.

The larvae appear to be in form somewhat like those of Zygaenidae; but with the same sort of remarkable clothing, in the form of tufts and brushes, that we find in Lymantriidae. A cocoon is formed. In Britain no member of this family is to be met with, but _Naclia ancilla_ may formerly have been a native; _Syntomis phegea_ has occurred here; probably an escaped example that had been introduced in one of its earlier stages.

[Illustration: Fig. 194—_Trichura_, sp. × 2/1. Demerara.]

FAM. 16. ZYGAENIDAE (_Burnet-Moths_).—This family is one about the limits and characters of which much difference of opinion prevails. As exemplified by our Burnet-moths it is characterised (in addition to the points given in the table) by the peculiar, flexible antennae; these are a little thicker before the tip, but are curved and pointed at the extremity, and without pectinations in the male. There is an elongate proboscis; bladder-like organs at the sides of the first abdominal segment are not present. The pupa is softer than is usual in the Macrolepidoptera, and the parts are less firmly fixed together, so that unusual mobility exists; six of the intersegmental membranes {391}are free, and the abdomen has much power of movement; there is no eye-collar; the antennae, hind legs, and proboscis-tips stretch backwards as far as the fifth or sixth abdominal segment, the tips being quite free; on the dorsal plates of the abdomen there are rows of minute elevations reminding one of the teeth existing in pupae that live in stems or galleries. This is altogether a peculiar pupa; it lives closely enclosed in a small hard cocoon, and its great capacity for movement is perhaps connected with the fact that the pupa itself manages to force its way through the cocoon in anticipation of the emergence of the moth. This cocoon is fastened tightly to a stem, and is covered with a substance that gives it a glazed appearance. The larvae are objects of a baggy nature, with inferior coloration, consisting of large dark blotches on a light ground, and without any remarkable development of their somewhat feeble system of hairs. Numerous small moths from the tropics are assigned to the family; they are most of them conspicuously marked and coloured, and like our Burnets are probably diurnal.

[Illustration: Fig. 195—_Hampsonia pulcherrima._ Wings on right side detached and denuded to show nervuration. India. (After Swinhoe.)]

The family Chalcosiidae is reduced by Hampson to the position of a sub-family of Zygaenidae. It consists of a large variety of diurnal moths of varied and brilliant colours, with an expanse of wing large in comparison with the typical Zygaenae, and with the antennae pectinate or flabellate to the tip. Some of these Insects (which are as conspicuous as possible in appearance, at any rate in a cabinet, the East Indian _Cadphises moorei_ _e.g._) are considered to be destitute of any special "protection." _Histia_ is a genus of remarkable cruciform moths, of a mixture of black and metallic colours, with carmine-tinted bodies. _Hampsonia pulcherrima_ (East India) is a curious moth of butterfly form and coloration, red and black with yellow patches, and with some of the nervules distorted, as if they had been forced apart in certain spots in order to accommodate these patches.

Two or three hundred species of Chalcosiidae are recorded. They are specially characteristic of the Indo-Malayan region.

{392}FAM. 17. HIMANTOPTERIDAE (THYMARIDAE of some authorities) are placed by Hampson in the sub-family Phaudinae of Zygaenidae characterised by the absence of the mouth-parts. The Himantopteridae are small moths, and have the scales on the wings very imperfect and hair-like; the hind wings form long slender tails, so that the Insects scarcely look like moths. They are peculiar to India and Africa. In the South African genus _Dianeura_ (belonging really to Phaudinae) also the wings are scaleless and nearly transparent.

FAM. 18. HETEROGYNIDAE.—Consists of the single genus _Heterogynis_ which has hitherto been found only in the south of Europe. This is an important form connecting Zygaenidae and Psychidae. The larvae resemble those of Zygaena, and construct an oval cocoon for their metamorphosis. The male issues as a small moth of smoky colour, the scales being but imperfect; the female chrysalis shows no trace of any appendages, and the imago is practically a maggot, and never leaves the cocoon; in it she deposits her eggs, and the young larvae hatch there.[275]

FAM. 19. PSYCHIDAE.—Small, or moderate-sized moths, with imperfect scales, and little or no colour beyond certain shades of duskiness; the sexes very different, the female being wingless and sometimes quite maggot-like; the male often with remarkable, bipectinate antennae, the branches sometimes very long and flexible. Larva inhabiting a case that it carries about. This family consists of Insects unattractive in appearance but presenting some points of great interest. It is frequently stated that the Psychidae are destitute of scales, but Heylaerts states[276] that, in addition to hairs, scales of a more or less imperfect formation are present in all, but that they are, like those of some Sphingidae (_Macroglossa_), very easily detached. There is much difference in the females, some having well-developed legs, while others are not only apterous, but are bare and destitute of appendages like a maggot, while in certain cases (Fig. 196, G), the head is reduced in size and is of peculiar form so as to make the Insect look really like the larva of one of the parasitic Diptera. These females never leave their cases, but deposit their eggs {393}therein, and inside, also, their former pupa-skin; and here the young hatch; the peculiar little larvae are very numerous, and it is suggested that they make a first meal on the body of their parent, but this we believe has not been satisfactorily ascertained. Great differences as to the condition of the legs, antennae, etc., are said to exist in species of the same genus. There is also a remarkable diversity in the pupae of the females; the male sex being normal in this respect. Some of the female pupae are destitute of wing-sheaths and all other appendages, while others are said to possess them, though there are no wings at all in the imago (_Fumea_, _e.g._).[277] Great difficulties attend the study of these case-bearing Insects, and several points require careful reconsideration, amongst them the one we have just mentioned. The males fly rapidly in a wild manner, and may sometimes be met with in swarms; their lives are believed to be very brief, rarely exceeding a couple of days, and sometimes being limited to a few hours.

[Illustration: Fig. 196—Metamorphosis of _Monda rhabdophora_. Ceylon. A, Larva in case, nat. size; B, larva itself, magnified; C, case of female during pupation; D, case of male during pupation; E, female pupa, magnified; F, male moth, nat. size; G, female moth, magnified. (From unpublished drawings by Mr. E. E. Green).]

The larvae are called basket-worms, and their baskets or cases are well worthy of attention. Their variety is remarkable; the most extraordinary are some of the genus _Apterona_ Fig. 197, B, which perfectly resemble the shells of Molluscs such as snails; indeed, the specimens in the collection at the British Museum were sent there as shells. This case is not, like those of other Psychidae, constructed of earth or vegetable matter, but is of silk and is in texture and appearance exactly {394}like the surface of a shell. _Psyche helix_ is, according to Ingenitzky,[278] found in great numbers near Lake Issyk-kul in Central Asia, where the larvae feed, in their snail-shell-like cases, on a grass, just like snails. Only females could be reared from these larvae. The case of _Chalia hockingi_ (Fig. 197, C) consists of little pieces of wood cut to the proper lengths, and spirally arranged, so as to form a construction that would be quite a credit to our own species. In some of the Canephorinae we meet with long cylindrical cases, like those of Caddis-worms, or of Tineid larvae.

[Illustration: Fig. 197—Baskets, or cases, of Psychidae. A, _Amicta quadrangularis_; B, _Apterona_ (or _Cochlophora_) _valvata_; C, _Chalia hockingi_.]

Riley has given an account of several points in the structure and natural history of one of the North American basket- or bag-worms, _Thyridopteryx ephemeraeformis_; one of his points being the manner in which the newly hatched larva forms its case.[279] This question has also been discussed by Packard.[280] The larvae when hatched in unnatural conditions will make use of fragments of paper, cork, etc., for the case; the act of construction takes one or two hours, and the larva does not eat till the case is completed. It walks in a peculiar manner, the legs of the third pair being moved forwards together, as if they were the prongs of a fork.

This family is already one of considerable extent, but its study, as already remarked, is but little advanced. Some naturalists are inclined to place it among the Tineidae, but it is connected with Zygaenidae by means of Heterogynidae. Mr. Meyrick divides it, placing _Psyche_ and _Sterrhopteryx_ (the forms representing, according to his ideas, the family Psychidae in Britain) in the series Psychina which includes Zygaenidae. He {395}removes the other British genera, _Fumea_, and _Epichnopteryx_, to Tineidae near _Solenobia_ and _Taleporia_. The group Canephorinae, to which the two genera in question belong, was long since separated from Psychidae by Herrich-Schäffer, but this course was condemned by Heylaerts. Parthenogenesis has been thought by some to occur in numerous species in this family, but Heylaerts says that it is limited to _Apterona crenulella_ var. _helix_, and even of this species males are found in certain localities.

FAM. 20. COSSIDAE (_Goat-Moths_, or _Carpenter-Worms_).—Moths of moderate, or rather large size, without proboscis, frequently with a dense covering of matted, imperfect scales; the pattern being vague. The larvae bore into trees in which they often make large burrows, leaving holes from which sap exudes. Our common Goat-moth is a good specimen of this family, which is a very widely distributed one. The Australian genus _Ptilomacra_ has very large, pectinated antennae in the male. The larvae of Cossidae are nearly bare of clothing and are unadorned; they form a slight cocoon of silk mixed with gnawed wood. The pupa of the Goat-moth is remarkable for the great development of the rows of teeth on the dorsal aspects of the segments of the abdomen, and for the absence of consolidation in this part, six of the intersegmental incisions being free, and the ventral aspect almost membranous. Very little is known as to other pupae of the family. It is believed that the generations of these Insects are fewer than usual, the growth of the larva occupying a period of two or three years. The larva of _Zeuzera aesculi_ forms a temporary cocoon in which it passes a winter-sleep, before again feeding in the spring.[281] It is a moot question whether the Zeuzeridae should be separated from the Cossidae or not. The group includes our Wood-leopard moth, which, like many other Zeuzerids, is spotted in a very striking but inartistic manner. The position the family Cossidae should occupy in an arrangement of the Lepidoptera is a very difficult question. Some consider the Insects to be allied to Tortricidae. The wing-nervuration of _Cossus_ is very peculiar and complex, there being four or five cells on the front wing, and three on the hind one. Meyrick places Zeuzeridae as a family of his series Psychina, but separates Cossidae proper (he calls them Trypanidae) as a family of the series Tortricina.

{396}FAM. 21. ARBELIDAE.—Closely allied to Cossidae, but without frenulum, and with less complex wing-nervures. A small family believed to be similar to Cossidae in the life-history. The tropical African Arbelidae are considered by Karsch to be a distinct family, Hollandiidae.

FAM. 22. CHRYSOPOLOMIDAE.—This family has been established by Dr. Aurivillius[282] for an African genus, allied in wing-nervuration to Cossidae; the Insects are like Lasiocampidae.

FAM. 23. HEPIALIDAE (_Ghost-_ and _Swift-Moths_).—Moths of very diverse size, some gigantic; wings not fitting together well at the bases; without a frenulum; no proboscis; the scales imperfect; the nervures complex. The Hepialidae are extremely isolated amongst the Lepidoptera; indeed, they have really no allies; the conclusion that they are connected with the Micropterygidae being certainly erroneous. Although but small in numbers—only about 150 species being known—they exhibit a remarkable variety in size and colour. Many are small obscure moths, while others are of gigantic size—six or seven inches across the wings—and are amongst the most remarkably coloured of existing Insects. The great _Charagia_ of Australia, with colours of green and rose, bearing white spots, are remarkable. The South African _Leto venus_ is of large size, and has an astonishing supply of glittering metallic splashes on the wings, making a barbaric but effective display. The South Australian _Zelotypia staceyi_, of enormous size, is also a handsome moth; but the majority of species of the family are adorned only in the feeblest manner.

Very little is known as to the larvae; they are either subterranean, feeding on roots, or they live in the wood of trees and shrubs. They are nearly bare, and are apparently the lowest type of Bombycid larva. At the same time, it would appear there is considerable variety amongst them. Packard says[283] the young larva of _Hepialus mustelinus_ has the arrangement of setae that is normal in Tineidae. The larva of _H. humuli_ seems to be a very simple form, but _H. hectus_ shows a considerable amount of divergence from it. They probably live for several years; the larva of _H. argenteo-maculatus_ in North America lives for three years, at first eating the roots of Alder and then entering the {397}stems. The pupae are also peculiar. They are of unusually elongate, cylindrical form, with comparatively feeble integument, but with a considerable development of chitinous, elevated, toothed ridges, on the dorsal aspect, and a very strong ridge of this kind on the ventral surface of the seventh segment; the wing-sheaths are short; it is very difficult to distinguish the full number of abdominal segments. These pupae are remarkably agile, and by wriggling and kicking are able to move a considerable distance; it is said that they can force themselves to the surface even when the superficial soil is quite hard. We cannot consider this pupa naturally placed amongst either the pupae obtectae or incompletae of Chapman.

[Illustration: Fig. 198—Pupa of _Hepialus lupulinus_. Britain. A, Ventral; B, dorsal aspect.]

We have already remarked that little is known as to the life-histories. The species are probably prolific, a female of _H. thule_ having been known to deposit more than 2000 eggs. Of the Australian forms little more is known[284] than that they live in the wood of trees and shrubs, and are rapidly disappearing; we may fear that some are extinct without ever having been discovered, and others, also unknown but still existing, may disappear only too soon; the wasteful destruction of timber in Australia having been deplorable.

The peculiar habits of the Hepialidae are not likely to bring the Insects to the net of the ordinary collector, and we believe they never fly to light, hence it is probable that we are acquainted with only a small portion of the existing species; their distribution is very wide, but Australia seems to be their metropolis, and in New Zealand twelve species are known. The genera as at present accepted are remarkable for their wide distribution. _Leto_ is said to occur in South Africa and in the {398}Fiji Islands; but we must repeat that the study of these interesting Insects is in a very primitive state, and our present knowledge of their distribution may be somewhat misleading.

The habits of the European _Hepialus_ in courtship have been observed to a considerable extent and are of great interest, an astonishing variety and a profound distinction in the methods by which the sexes are brought together having been revealed.

_H. humuli_, our Ghost-moth, is the most peculiar. Its habits were detected by Dr. Chapman.[285] The male is an Insect of exceptional colour, being white above, in consequence of a dense formation of imperfect scales; the female is of the brownish tints usual in Swift-moths. In the month of June the male selects a spot where he is conspicuous, and hovers persistently there for a period of about twenty minutes in the twilight; his colour has a silvery-white, glistening appearance, so that the Insect is really conspicuous notwithstanding the advanced hour. Females may be detected hovering in a somewhat similar manner, but are not conspicuous like the male, their colour being obscure; while so hovering they are ovipositing, dropping the eggs amongst the grass. Females that have not been fertilised move very differently and dash about in an erratic manner till they see a male; they apparently have no better means of informing the hovering male of their presence than by buzzing near, or colliding with him. Immediately this is done, the male abandons his hovering, and coupling occurs. There can be little doubt that the colour of the male attracts the female; but there is a variety, _hethlandica_, of the former sex coloured much like the female, and in some localities varieties of this sort are very prevalent, though in others the species is quite constant. This variation in the colour of the males is very great in Shetland,[286] some being quite like the females. In _H. hectus_ the two sexes are inconspicuously and similarly coloured. The male hovers in the afternoon or evening in a protected spot, and while doing so diffuses an agreeable odour—said by Barrett to be like pine-apple—and this brings the female to him, much in the same manner as the colour of _H. humuli_ brings its female. The hind legs of the male {399}are swollen, being filled with glands for secreting the odorous matter.[287] This structure has led to the suggestion of the generic name _Phymatopus_ for the Insect. Turning to other species of the genus, we find that the normal relative rôles of the sexes are exhibited, but with considerable diversity in the species. In _H. lupulinus_ the males fly about with rapidity, while the female sits on a stem and vibrates her wings; she thus attracts the males, but they do not perceive her unless happening to come within three or four feet, when they become aware of her proximity, search for and find her. It is doubtful whether the attraction is in this case the result of an odour; it would appear more probable that it may be sound, or that the vibration of the wings may be felt by the male.

In _H. sylvinus_, _H. velleda_ and _H. pyrenaicus_ less abnormal modes of attracting the males occur, the individuals of this latter sex assembling in great numbers at a spot where there is a female. In the first of the three species mentioned the female sits in the twilight on the stem of some plant and vibrates the wings with rapidity; she does not fly; indeed, according to Mr. Robson, she does not till after fertilisation move from the spot where she emerged. In _H. pyrenaicus_ the female is quite apterous, but is very attractive to the males, which as we have said, assemble in large numbers near her. Thus within the limits of these few allied forms we find radically different relations of the sexes.

1. The male attracts the female—(A) by sight (_H. humuli_); (B) by odour (_H. hectus_).

2. The female attracts the male—(A) by vibration of wings (_H. lupulinus_ and _H. sylvinus_); (B) without vibration, but by some means acting at a distance (_H. velleda_, _H. pyrenaicus_).

Little or nothing is known as to the habits of the great majority of the more remarkable forms of the family. The gigantic Australian forms are believed to be scarcely ever seen on the wing.

The Hepialidae differ from other Lepidoptera by very important anatomical characters. The absence of most of the {400}mouth-parts is a character common to them and several other divisions of Lepidoptera; but the labial palpi are peculiarly formed in this family, being short and the greater portion of their length consisting of an undivided base, which probably represents some part of the labium that is membranous in normal Lepidoptera. The thoracic segments are remarkably simple, the three differing less from one another than usual, and both meso- and meta-notum being much less infolded and co-ordinated. The wings are remarkable for the similarity of the nervuration of the front and hind wings, and by the cell being divided by longitudinal nervules so as to form three or four cells. On the inner margin of the front wing there is near the base an incision marking off a small prominent lobe, the jugum of Prof. Comstock. Brandt mentions the following anatomical peculiarities,[288] viz. the anterior part of the alimentary canal is comparatively simple; the respiratory system is in some points like that of the larva; the heart is composed of eight chambers; the appendicular glands of the female genitalia are wanting. The testes remain separate organs throughout life. The chain of nerve ganglia consists of the supra- and infra-oesophageal, three thoracic, and five abdominal, ganglia, while other Lepidoptera have four abdominal.

FAM. 24. CALLIDULIDAE.—A small family of light-bodied diurnal moths having a great resemblance to butterflies. In some the frenulum is present in a very rudimentary condition, and in others it is apparently absent. _Cleosiris_ and _Pterodecta_ are very like butterflies of the Lycaenid genus _Thecla_. Although fifty species and seven or eight genera are known, we are quite ignorant of the metamorphoses. Most of the species are found in the islands of the Malay Archipelago, but there are a few in East India.

FAM. 25. DREPANIDAE (or DREPANULIDAE). (_Hook-tips_).—The larger moths of this family are of moderate size; many of the species have the apex of the front wing pointed or even hooked; some have very much the appearance of Geometrid moths; they resemble very different members of that family. _Oreta hyalodisca_ is remarkable on account of the very large, transparent patch on each front wing, though the other species of the genus have nothing of the sort. In the genus _Deroca_ we {401}find Insects with the scales imperfect, they being few and small and approximating in form to hairs; in _D. hyalina_ scales are nearly entirely absent. In other genera, _e.g._ _Peridrepana_, _Streptoperas_, there is only a very inferior state of scale-formation. The few larvae that are known are peculiar; they are nearly bare of hair, without the pair of terminal claspers, while the body is terminated by a long tubular process. They form a slight cocoon among leaves.

The members of the family were formerly much misunderstood, and were assigned to various positions in the Order. There are now about 30 genera, and 150 species known, the geographical distribution of the family being very wide. In Britain we have half a dozen species. _Cilix glaucata_ (better known as _C. spinula_) is said "to undoubtedly imitate" the excrement of birds. No doubt the Insect resembles that substance so as to be readily mistaken for it. This Insect has a very wide distribution in North America, Europe and East India, and is said to vary so much in the structure of its organs as to justify us in saying that the one species belongs to two or three genera.

[Illustration: Fig. 199—Mature larva of _Apoda testudo_, on beech-leaf. Britain.]

FAM. 26. LIMACODIDAE (or EUCLEIDAE).—These are somewhat small moths, of stout formation, sometimes very short in the body, and with rather small wing-area. The family includes however at present many Insects of diverse appearance; there are numerous forms in which apple-green is a prominent colour; some bear a certain resemblance to the Swifts, others to Noctuids; some, _Rosema_ and _Staetherinia_, are of extraordinary shapes; certain very small forms, _Gavara_, _Ceratonema_, resemble Tortricids or Tineids; a few even remind one of Insects of other Orders; so that the group is a mimetic one. _Nagoda nigricans_ (Ceylon) has the male somewhat like a Psychid, while the female has a different system of coloration and wing-form. In _Scopelodes_ the palpi are in both sexes remarkable; elongated, stiff, directed upwards and brush-like at the tip. Altogether there are about 100 genera and 400 species known; the distribution of the family is very wide {402}in both hemispheres, but these Insects do not occur in insular faunas. In Britain we have two genera, _Heterogenea_ and _Apoda_ (better known as _Limacodes_[289]), each with a single species.

[Illustration: Fig. 200—Larva of _Apoda testudo_ just hatched. A, Dorsal view of larva; B, C, D, a spine in different states of evagination. All magnified. (After Chapman.)]

The early stages of these Insects are of great interest. The eggs, so far as known, are peculiar flat oval scales, of irregular outline and transparent; we have figured an example in Vol. V. Fig. 83. The eggs of the same moth are said to vary much in size, though the larvae that emerge from them differ little from one another in this respect. The latter are peculiar, inasmuch as they have no abdominal feet, and the thoracic legs are but small; hence the caterpillars move in an imperceptible gliding manner that has suggested for some of them the name of slug-worms. The metamorphoses of a few are known. They may be arranged in two groups; one in which the larva is spinose or armed with a series of projections and appendages persisting throughout life; while in the members of the second group the spines have only a temporary existence. At the moment the young larva of _Apoda testudo_ emerges from the egg it has no conspicuous spines or processes, and is an extremely soft, colourless creature,[290] but it almost immediately displays a remarkable system of complex spines. These really exist in the larva when it is hatched, and are thrust out from pits, as explained by Dr. Chapman. In the succeeding stages, the spines become modified in form, and the colour of the body and the nature of {403}the integument are much changed, so that in the adult larva (Fig. 199) the spines have subsided into the condition of mere prominences, different in colour from the rest of the surface. These larvae appear to be destitute of a head, but there really exists a large one which is retracted, except during feeding, into the body; the five pairs of abdominal feet of the larvae of allied families are replaced by sucker-like structures on the first eight abdominal segments. The spinneret of the mouth is not a pointed tubular organ, but is fish-tailed in shape, and hence disposes the silky matter, that aids the larva in moving on the leaves, in the form of a ribbon instead of that of a thread. It has been stated that these peculiar larvae "imitate" the coloured galls frequently found on the leaves of trees. The North American forms of this family have very varied and most extraordinary larvae.[291] In the pretty and conspicuous larva of _Empretia stimulea_, the tubercles or processes of the body are, in the later stages, armed with hairs, that contain a poisonous or irritating fluid, said to be secreted by glands at the bases of the processes. These hairs are readily detached and enter the skin of persons handling the caterpillars. The larva of the North American Hag-moth, _Phobetron pithecium_, is a curious object, bearing long, fleshy appendages covered with down. Hubbard makes the following statement as to the instincts of this larva:[292]—"The hag-moth larvae do not seek to hide away their cocoons, but attach them to leaves and twigs fully exposed to view, with, however, such artful management as to surroundings and harmonising colours that they are of all the group the most difficult to discover. A device to which this Insect frequently resorts exhibits the extreme of instinctive sagacity. If the caterpillar cannot find at hand a suitable place in which to weave its cocoon, it frequently makes for itself more satisfactory surroundings by killing the leaves, upon which, after they have become dry and brown in colour, it places its cocoon. Several of these caterpillars unite together, and selecting a long and vigorous immature shoot or leader of the orange tree, they kill it by cutting into its base until it wilts and bends over. The leaves of a young shoot in drying turn a light tan-color, which {404}harmonises most perfectly with the hairy locks of the caterpillar covering the cocoon. The latter is, consequently, not easily detected, even when placed upon the exposed and upturned surface of the leaf."

The cocoons of Limacodidae are unusually elaborate, the larva forming a perfect lid in order to permit itself to escape when a moth. Chapman states that the larva lies unchanged in the cocoon all winter, moulting to a pupa in the spring, and that the pupa escapes from the cocoon previous to the emergence of the moth.[293] Both Chapman and Packard look on the family as really nearer to Microlepidoptera than to Bombyces; Meyrick (calling it Heterogeneidae) places it at the end of his series Psychina next Zygaenidae.

We may allude here to the little moths, described by Westwood under the name of _Epipyrops_,[294] that have the extraordinary habit of living on the bodies of live Homopterous Insects of the family Fulgoridae in India. What their nutriment may be is not known. The larva exudes a white flocculent matter, which becomes a considerable mass, in the midst of which the caterpillar changes to a pupa. Westwood placed the Insect in Arctiidae; Sir George Hampson suggests it may be a Limacodid, and this appears probable.

FAM. 27. MEGALOPYGIDAE (or LAGOIDAE).—The American genera, _Megalopyge_ and _Lagoa_, are treated by Berg and by Packard[295] as a distinct family intermediate between Saturniidae and Limacodidae. The larva is said by the latter authority to have seven pairs of abdominal feet instead of five pairs—the usual number in Lepidoptera. When young the caterpillars of _Lagoa opercularis_ are white and resemble a flock of cotton wool. When full grown the larva presents the singular appearance of a lock of hair, moving in a gliding, slug-like manner. Under the long silky hair there are short, stiff, poison-hairs. The larva forms a cocoon, fitted with a hinged trap-door for the escape of the future moth. This curious larva is destroyed by both Dipterous and Hymenopterous parasites.

FAM. 28. THYRIDIDAE.—A small family of Pyraloid moths, exhibiting considerable variety of form and colour, frequently with hyaline patches on the wings. They are mostly small {405}Insects, and contain no very striking forms. Some of them look like Geometrids of various groups. The family is widely distributed in the tropical zone, and includes 25 genera, of which _Rhodoneura_, with upwards of 100 species, is the chief one. The larvae are said to be similar to those of Pyralidae. This family is considered by Hampson and Meyrick to be ancestral to butterflies.[296]

[Illustration: Fig. 201.—Lappet-moth, _Gastropacha quercifolia_, ♀. Britain.]

FAM. 29. LASIOCAMPIDAE (_Eggers_, _Lappet-moths_). Usually large Insects densely covered with scales, without frenulum, but with the costal area of the hind wing largely developed, and the male antennae beautifully pectinate, Lasiocampids are easily recognised. They are well known in Britain, though we have but few species. The flight of some of the species is powerful, but ill-directed, and the males especially, dash about as if their flight were quite undirected; as indeed it probably is. The difference in the flight of the two sexes is great in some species. In the genus _Suana_ and its allies we meet with moths in which the difference in size of the two sexes is extreme; the males may be but 1½ inches across the wings, while the very heavy females may have three times as great an expanse. Kirby separates these Insects to form the family Pinaridae; it includes the Madagascar silkworm, _Borocera madagascariensis_. The African genus _Hilbrides_ is remarkable for the wings being destitute of scales, and consequently transparent, and for being of very slender form like a butterfly. The eggs of Lasiocampidae are smooth, in certain cases spotted in an irregular manner like birds' eggs. Sometimes the parent covers them with hair. The larvae are clothed with a soft, woolly hair, as well as with a shorter and stiffer kind, neither beautifully arranged nor highly coloured, and thus differing from the caterpillars of Lymantriidae; this hair in some cases has very irritating properties. Cocoons of a close and compact nature are formed, and hairs from the body are frequently mixed with the cocoon. In {406}some species the walls of the cocoons have a firm appearance, looking very like egg-shell—a fact which is supposed to have given rise to the name of Eggers. Professors Poulton and Meldola have informed us that this appearance is produced by spreading calcium oxalate on a slight framework of silk, the substance in question being a product of the Malpighian tubes.[297] In various families of Lepidoptera it happens that occasionally the pupa exists longer than usual before the appearance of the perfect Insect, and in certain members of this family—notoriously in _Poecilocampa populi_, the December moth—this interval may be prolonged for several years. There is not at present any explanation of this fact. It may be of interest to mention the following case:—From a batch of about 100 eggs deposited by one moth, in the year 1891 (the Puss-Moth of the family Notodontidae), some sixty or seventy cocoons were obtained, the feeding up of all the larvae having been effected within fourteen days of one another; fourteen of the Insects emerged as moths in 1892; about the same number in 1893; in 1894, twenty-five; and in 1895, eleven emerged. Lasiocampidae is a large family, consisting of some 100 genera and 500 or more species, and is widely distributed. It is unfortunately styled Bombycidae by some naturalists.

FAM. 30. ENDROMIDAE.—The "Kentish glory," _Endromis versicolor_, forms this family; it is a large and strong moth, and flies wildly in the daytime in birch-woods. The larva has but few hairs, and is said when young to assume a peculiar position, similar to that of saw-fly larvae, by bending the head and thorax backwards over the rest of the body.

FAM. 31. PTEROTHYSANIDAE.—Consists of the curious East Indian genus _Pterothysanus_, in which the inner margins of the hind wings are fringed with long hairs. They are moths of slender build, with large wing-expanse, black and white in colour, like Geometrids. There is no frenulum. Metamorphoses unknown.

FAM. 32. LYMANTRIIDAE.—(Better known as LIPARIDAE). These are mostly small or moderate-sized moths, without brilliant colours; white, black, grey and brown being predominant; with highly-developed, pectinated antennae in the male. The larva is very hairy, and usually bears tufts or brushes of shorter hairs, {407}together with others much longer and softer, these being sometimes also amalgamated to form pencils; the coloration of these larvae is in many cases very conspicuous, the tufts and pencils being of vivid and strongly contrasted colours. Some of these hairy larvae are poisonous. A cocoon, in which much hair is mixed, is formed. The pupae are remarkable, inasmuch as they too are frequently hairy, a very unusual condition in Lepidoptera. The Lymantriidae is one of the largest families of the old group Bombyces; it includes some 180 genera and 800 species, and is largely represented in Australia. _Dasychira rossii_ is found in the Arctic regions. In Britain we have eight genera represented by eleven species; the Gold-tails, Brown-tails and Vapourer-moths being our commonest Bombyces, and the latter being specially fond of the London squares and gardens, where its beautiful larva may be observed on the leaves of roses. Most of the Lymantriidae are nocturnal, but the male Vapourer-moth flies in the daytime. In this family there are various species whose females have the wings small and unfit for flight, the Insects being very sluggish, and their bodies very heavy. This is the state of the female of the Vapourer-moth. The males in these cases are generally remarkably active, and very rapid on the wing.

Some of these moths increase in numbers to an enormous extent, and commit great ravages. _Psilura monacha_—the Nun, "die Nonne" of the Germans,[298]—is one of the principal troubles of the conservators of forests in Germany, and great sums of money are expended in combating it; all sorts of means for repressing it, including its infection by fungi, have been tried in vain. The caterpillars are, however, very subject to a fungoid disease, communicated by natural means. It is believed, too, that its continuance in any locality is checked after a time by a change in the ratio of the two sexes. It is not a prolific moth, for it lays only about 100 eggs, but it has been shown that after making allowance for the numerous individuals destroyed by various enemies, the produce of one moth amounts in five generations to between four and five million individuals. The larva feeds on Coniferae, and on many leafy trees and shrubs. The young {408}larva is provided with two sets of setae, one set consisting of very long hairs, the other of setae radiating from warts; each one of this second set of spines has a small bladder in the middle, and it has been suggested that these assist in the dissemination of the young caterpillars by atmospheric means.[299] These aerostatic setae exist only in the young larva. The markings of the moth are very variable; melanism is very common both in the larva and imago; it has been shown conclusively that these variations are not connected, as black larvae do not give a larger proportion of black moths than light-coloured caterpillars do. In England this moth is never injurious. A closely allied form, _Ocneria dispar_, was introduced by an accident into North America from Europe about thirty years ago; for twenty years after its introduction it did no harm, and attracted but little attention; it has, however, now increased so much in certain districts that large sums of money have been expended in attempting its extirpation.

_Dasychira pudibunda_ has occasionally increased locally to an enormous extent, but in the limited forests of Alsace the evil was cured by the fact that the caterpillars, having eaten up all the foliage, then died of starvation.[300] _Teara melanosticta_ is said to produce columns of processionary caterpillars in Australia.

FAM. 33. HYPSIDAE (or AGANAIDAE).—A family of comparatively small extent, confined to the tropical and sub-tropical regions of the Eastern hemisphere. The colours are frequently buff and grey, with white streaks on the outer parts of the wings. We have nothing very like them in the European fauna, our species of _Spilosoma_ are perhaps the nearest approach. In _Euplocia_ the male has a pouch that can be unfolded in front of the costa at the base of the anterior wing; it is filled with very long, peculiar, hair-like scales growing from the costal margin; both sexes have on each side of the second abdominal segment a small, projecting structure that may be a sense-organ. The female is more gaily coloured than the male.

FAM. 34. ARCTIIDAE.—With the addition recently made to it of the formerly separate family Lithosiidae, Arctiidae has become the most extensive family of the old Bombycid series of moths, comprising something like 500 genera and 3000 species. Hampson recognises four sub-families—Arctiinae, Lithosiinae, {409}Nolinae, Nycteolinae,—to which may be added others from America—Pericopinae, Dioptinae, Ctenuchinae; these sub-families being treated as families by various authors. The sub-family Arctiinae includes our Tiger- and Ermine-moths, and a great many exotic forms of very diverse colours and patterns; the species of this division are, on the whole, probably more variable in colour and markings than in any other group of Lepidoptera. There are many cases of great difference of the sexes; in the South American genus _Ambryllis_ the male is remarkable for its hyaline wings with a few spots; while the female is densely scaled, and very variegate in colour. There are some cases (the South European genus _Ocnogyna_) where the female is wingless and moves but little, while the male flies with great rapidity. _Epicausis smithi_, from Madagascar, one of the most remarkable of moths, is placed in this division of Arctiidae; it is of a tawny colour, variegate with black; the abdomen of this latter colour is terminated by a large tuft of long scarlet hairs; the Insect has somewhat the appearance of a Hummingbird-hawkmoth. _Ecpantheria_ is an extensive genus of tropical American moths (having one or two species in North America), of black and white or grey colours, with very complex markings; the male in some species has a part of the hind wing produced as a tail, or lobe, of a different colour.

The sub-family Pericopinae are almost peculiar to South America (two species of _Gnophaela_ exist in North America); some of this sub-family bear a great resemblance to Heliconiid butterflies.

The Dioptinae are likewise American moths of diurnal habits, and many of them bear a striking resemblance to the Ithomiid butterflies they associate with when alive.

The sub-family Lithosiinae is of great extent; our native "Footmen" give a very good idea of it; the moths are generally of light structure, with long, narrow front wings; a simple system of yellow and black colour is of frequent occurrence. Many of this group feed in the larval state on lichens. Hampson includes in this group the Nyctemeridae—light-bodied diurnal moths, almost exclusively of black and white colours, of Geometrid form, frequently treated as a distinct family.

The sub-family Nolinae is a small group of rather insignificant Insects, in appearance like Pyralids or Geometrids; four or five {410}species are native in Britain. Packard maintains the family Nolidae as distinct.[301]

The sub-family Nycteolinae consists of a few small moths the position of which has always been uncertain; _Nycteola_ (better known as _Sarrothripus_), _Halias_, and _Earias_ are all British genera that have been placed amongst Tortrices, to which they bear a considerable resemblance. _Sarrothripus_ is at present placed by Hampson in Noctuidae, by others in Lithosiidae, by Meyrick in Arctiidae. The sub-family forms the family Cymbidae of Kirby;[302] it includes at present only about 70 species, all belonging to the Eastern hemisphere. Two types of larvae are known in it: one bare, living exposed on leaves; the other, _Earias_, hairy, living among rolled-up leaves. _Halias prasinana_ is known from the testimony of numerous auditors to produce a sound when on the wing, but the _modus operandi_ has not been satisfactorily ascertained. Sound-production seems to be of more frequent occurrence in Arctiidae than it is in any other family of Lepidoptera; _Dionychopus niveus_ produces a sound by, it is believed, friction of the wings. In the case of the genera _Setina_ and _Chelonia_ the process is said to be peculiar to the male sex: Laboulbène believes it to proceed from drum-like vesicles situate one on each side of the base of the metathorax.[303]

FAM. 35. AGARISTIDAE.—An interesting assemblage of moths, many of them diurnal and of vivid colours, others crepuscular. There is considerable variety of appearance in the family, although it is but a small one, and many of its members remind one of other and widely separated families of Lepidoptera. The style and colour of the Japanese _Eusemia villicoides_ are remarkably like our _Arctia villica_. In some forms the antennae are somewhat thickened towards the tip and hooked, like those of the Skipper butterflies. The family consists at present of about 250 species, but we doubt its being a sufficiently natural one. It is very widely distributed, with the exception that it is quite absent from Europe and the neighbourhood of the Mediterranean Sea. In North America it is well represented. The larvae, so far as known, are not very remarkable; they have some lateral tufts of hair, as well as longer hairs scattered over the body.

{411}The male of the Indian _Aegocera tripartita_ has been noticed to produce a clicking sound when flying, and Sir G. Hampson has shown[304] that there is a peculiar structure on the anterior wing; he considers that this is rubbed against some spines on the front feet, and that the sound is produced by the friction. Though this structure is wanting in the acknowledged congeners of _A. tripartita_, yet it occurs in a very similar form in the genus _Hecatesia_, already noticed under Castniidae.

FAM. 36. GEOMETRIDAE (_Carpets_, _Pugs_, _etc._)—This very extensive family consists of fragile moths, only a small number being moderately stout forms; they have a large wing-area; the antennae are frequently highly developed in the males, but on this point there is much diversity. Either the frenulum or the proboscis is absent in a few cases. The caterpillars are elongate and slender, with only one pair of abdominal feet—placed on the ninth segment—in addition to the anal pair, or claspers. They progress by moving these two pairs of feet up to the thoracic legs, so that the body is thrown into a large loop, and they are hence called Loopers or Geometers. The family is universally distributed, and occurs even in remote islands and high latitudes; in Britain we have about 270 species. The family was formerly considered to be closely connected with Noctuidae, but at present the opinion that it has more intimate relations with the families we have previously considered is prevalent. Packard considers it near to Lithosiidae, while Meyrick merely places the six families, of which he treats it as composed, in his series Notodontina. Hampson adopts Meyrick's six families as subfamilies, but gives them different names, being in this respect more conservative than Meyrick, whose recent revision of the European forms resulted in drastic changes in nomenclature.[305] This classification is based almost exclusively on wing-nervuration. The number of larval legs and the consequent mode of walking is one of the most constant characters of the group; the few exceptions that have been detected are therefore of interest. _Anisopteryx aescularia_ has a pair of undeveloped feet on the eighth segment, and, according to Meyrick, its allies "sometimes show rudiments of the other two pairs." The larva of _Himera {412}pennaria_ is said to have in early life a pair of imperfect feet on the eighth segment, which disappear as the larva approaches maturity.

[Illustration: Fig. 202—Larva of _Amphidasis betularia_, reposing on a rose-twig. × 1. Cambridge.]

The position of the abdominal feet and claspers throws the holding power of the larva to the posterior part of the body, instead of to the middle, as in other caterpillars. This, combined with the elongate form, causes these larvae when reposing to assume attitudes more or less different from those of other larvae; holding on by the claspers, some of these Insects allow all the anterior parts of the body to project in a twig-like manner. The front parts are not, however, really free in such cases, but are supported by a thread of silk extending from the mouth to some point near-by. Another plan adopted is to prop the front part of the body against a twig placed at right angles to the supporting leaf, so that the caterpillar is in a diagonal line between the two (Fig. 202). Other Geometers assume peculiar coiled or spiral attitudes during a whole or a portion of their lives; some doing this on a supporting object—leaf or twig—while others hang down (_Ephyra pendularia_). Certain of the larvae of Geometridae vary in colour, from shades of brown to green; there is much diversity in this variation. In some species it is simple variation; in others it is dimorphism, _i.e._ the larvae are either brown or green. In other cases the larvae are at first variable, subsequently dimorphic. In _Amphidasis betularia_ it would appear that when the larva is hatched the dimorphism is potential, and that the future colour, whether {413}green or brown, is settled by some determining condition during the first period of larval life and cannot be subsequently modified.[306] According to Poulton, the dark tint is due in _A. betularia_ to colouring matter in the skin or immediately below it, and the green tint to a layer of fat between the hypodermis and the superficial muscles; this layer being always green, but more brightly green in the larvae that are of this colour externally. Much discussion has occurred about these larval attitudes and colours, and it seems probable that Professor Poulton has overrated the value of protection from birds, mammals and entomologists; the chief destroying agents being other than these, and not liable to be thus deceived, even if the vertebrates are. In some cases such resemblance as undoubtedly exists is not made the best use of. The larva shown in figure 202 bore a wonderful resemblance, when examined, to the rose-twigs it lived on, but the effect of this as a concealing agent was entirely destroyed by the attitude; for this, being on different lines to those of the plant, attracted the eye at once. This larva, and we may add numerous other larvae, could have been perfectly concealed by adopting a different attitude, but never did so; the position represented being constantly maintained except while feeding.

In some species of this family the adult females are without wings, or have them so small that they can be of no use for flight. This curious condition occurs in various and widely-separated groups of the Geometridae; and it would be naturally supposed to have a great effect on the economy of the species exhibiting it, but this is not the case. Some of the flightless females affect the highest trees and, it is believed, ascend to their very summits to oviposit. It has been suggested that they are carried up by the winged males, but this is probably only an exceptional occurrence; while, as they are known to be capable of ascending with rapidity by means of crawling and running, it may be taken for granted that this is the usual method with them. Some of these wingless females have been found in numbers on gas-lamps, and are believed to have been attracted by the light, as is the case with very many of the winged forms.[307] {414}Neither is the geographical distribution limited by this inferior condition of the most important of the organs of locomotion, for _Cheimatobia brumata_ (the Winter-moth) one of the species with flightless female, is a common and widely distributed Insect in Europe and North America.

Although the classification of this family is based almost entirely on wing-nervuration, yet there are some divisions of the Geometridae in which this character is remarkably variable, certain individuals frequently exhibiting considerable abnormality.[308] _Amphidasis betularia_ is believed to have changed its variation considerably in the course of the last fifty years. Previous to that time a black variety of the species was unknown, but it has now become common; and it is believed that other species of Geometridae are in process of exhibiting a similar phenomenon.[309]

FAM. 37. NOCTUIDAE (_Owlet-Moths_, _Eulen_ of the Germans).—This very extensive assemblage consists of moths rarely seen in the day-time, of generally sombre colours, with antennae destitute of remarkable developments in the male (except in a small number of forms); proboscis and frenulum both present; a complex sense-organ on each side of the body at the junction of the metathorax and abdomen. The number of species already known can scarcely be less than 8000; owing to their large numbers and the great general resemblance of the forms, their classification is a matter of considerable difficulty. Although the peculiar structure at the base of the thorax was long since pointed out, it has never received any thorough investigation. Few other remarkable structures have yet been discovered: the most interesting is perhaps the peculiarity in the hind wings of the males of certain Ommatophorinae recently pointed out by Sir G. F. Hampson[310]: in the genera _Patula_ and _Argiva_ the form of the hind wings is normal in the females, but in the male the anterior one-half of each of these wings is aborted, and the position of the nervures changed; this condition is connected with the development of a glandular patch or fold on the wing, and is remarkable as profoundly affecting a structure which is {415}otherwise so constant that the classification of the family is largely based on it.

[Illustration: Fig. 203—_Brephos notha._ Larva, newly hatched. Britain.]

The larvae are as a rule destitute of the remarkable adornments of hairs and armatures of spines that are so common in many of the families we have previously considered; they are fond of concealing themselves during the day and coming out at night to feed; many of them pass most of their time at, or beneath, the surface of the ground, finding nourishment in roots or the lower parts of the stems of plants; this is notably the case in the genus _Agrotis_, which is perhaps the most widely distributed of all the genera of moths. Such caterpillars are known as Cut-worms in North America.[311] The great resemblance, _inter se_, of certain of these Cut-worms, much astonished the American naturalist Harris, who found that larvae almost perfectly similar produced very different moths. The majority of Noctuid larvae have the usual number of legs, viz., three pairs of thoracic legs, four pairs of abdominal feet and the terminal claspers. In some divisions of the family there is a departure from this arrangement, and the abdominal feet are reduced to three, or even to two, pairs. One or two larvae are known—e.g. _Euclidia mi_—in which the claspers have not the usual function, but are free terminal appendages. When the abdominal legs are reduced in number (_Plusia_, e.g.) the larvae are said to be Half-loopers, or Semi-loopers, as they assume to some extent the peculiar mode of progression of the Geometrid larvae, which are known as Loopers. In the case of certain larvae, e.g. _Triphaena_, that have the normal number of feet, it has been observed that when first hatched, the one or two anterior pairs of the abdominal set are ill developed, and the larvae do not use them for walking. This is the case with the young larva of our British _Brephos notha_ (Fig. 203). Subsequently, however, this larva undergoes a considerable change, and appears in the form shown in Fig. 204. This interesting larva joins together two or three {416}leaves of aspen and lives between them, an unusual habit for Noctuid larvae. When about to pupate it bores into bark or soft wood to change to a pupa, Fig. 205; the specimen represented closed the hole of entry by placing two separate doors of silk across the burrow, as shown at _d_. The anal armature of this pupa is terminated by a curious transverse process. The systematic position of this interesting Insect is very uncertain: Meyrick and others associate it with the Geometridae.

[Illustration: Fig. 204—_Brephos notha._ Adult larva.]

[Illustration: Fig. 205 —_Brephos notha._ A, Pupa, ventral aspect; B, extremity of body, magnified; C, the pupa in wood; _d_, diaphragms constructed by the larva.]

The larva of _Leucania unipunctata_ is the notorious Army-worm that commits great ravages on grass and corn in North America. This species sometimes increases in numbers to a considerable extent without being observed, owing to the retiring habits of the larvae; when, however, the increase of numbers has been so great that food becomes scarce, or for some other cause—for the scarcity of food is supposed not to be the only reason—the larvae become gregarious, and migrate in enormous swarms: whence its popular name. The Cotton-worm, _Aletia xylinae_ is even more notorious on account of its ravages. Riley states[312] that in bad years the mischief it commits on the cotton crop causes a loss of £6,000,000, and that for a period of fourteen successive years the annual loss averaged about £3,000,000. This caterpillar strips the cotton plants of all but their branches. It is assisted in its work by another highly destructive Noctuid caterpillar, the Boll-worm, or larva of _Heliothis armigera_, which bores into the buds and pods. This {417}latter Insect attacks a great variety of plants, and has a very wide distribution, being found even in England, where happily it is always a rare Insect.

In Britain, as well as in parts of Northern Europe, a Noctuid moth, _Charaeas graminis_, occasionally increases to an enormous extent: its larva is called the Hill-grub and lives on the grass of pastures, frequently doing great damage in hill-lands. The increase of this moth seems to take place after the manner of an epidemic; a considerable number of years may pass during which it is scarcely seen, and it will then appear in unusual numbers in widely separated localities. This moth lays a large number of eggs, and is not completely nocturnal in habits; sometimes it may be seen on the wing in great numbers in the hottest sunshine, and it has been noticed that there is then a great disproportion of the sexes, the females being ten or twenty times as numerous as the males. In Australia, the Bugong moth, _Agrotis spina_, occurs in millions in certain localities in Victoria: this moth hibernates as an imago, and it formerly formed, in this instar, an important article of food with the aborigines. The powers of increase of another Noctuid moth—_Erastria scitula_—are of great value. Its habits have been described by Rouzaud.[313] On the shores of the Mediterranean the larva of this little moth lives on a Scale-Insect—_Lecanium oleae_—that infests the peach; and as the moth may have as many as five generations in a year, it commits laudable havoc with the pest. The larva is of remarkable form, very short and convex, with small head, and only two pairs of abdominal feet. The scale of the _Lecanium_ is of larger size than is usual in that group of Insects, and the young larva of the _Erastria_ buries itself, as soon as hatched, in one of the scales; it destroys successively numerous scales, and after having undergone several moults, it finds itself provided, for the first time, with a spinneret, when, with the aid of its silk, it adds to and adapts a Coccid scale, and thus forms a portable habitation; this it holds on to by means of the pair of anal claspers, which are of unusual form. The case is afterwards subjected to further alteration, so that it may serve as a protection to the creature when it has changed to a pupa. This moth is said to be free from the attacks of parasites, and if this be the case it is probable that its increase is regulated by the fact that {418}when the creature becomes numerous it thus reduces the food supply, so that its own numbers are afterwards in consequence diminished.

One of the most remarkable genera of British Noctuidae is _Acronycta_,[314] the larvae of which exhibit so much diversity that it has been suggested that the genus should be dismembered and its fragments treated as allied to several different divisions of moths. There are many points of interest in connection with the natural history of these _Acronycta_. _A. psi_ and _A. ridens_ are practically indistinguishable as moths, though the larvae are easily separated: the former species is said to be destroyed to an amazing extent by parasites, yet it remains a common Insect. The genus _Apatela_ is very closely allied to _Acronycta_, and Harris says that "_Apatela_ signifies deceptive, and this name was probably given to the genus because the caterpillars appear in the dress of Arctians and Liparians, but produce true owlet-moths or Noctuas."[315] The species of another British genus, _Bryophila_, possess the exceptional habit of feeding on lichens. Some of the American group Erebides are amongst the largest Insects, measuring seven or eight inches across the expanded wings.

The Deltoid moths are frequently treated as a distinct family, Deltoidae, perhaps chiefly because of their resemblance to Pyralidae. At present, however, they are considered to be separated from Noctuidae by no valid characters.

FAM. 38. EPICOPEIIDAE.—The genus _Epicopeia_ consists of only a few moths, but they are amongst the most extraordinary known: at first sight they would be declared without hesitation to be large swallow-tail butterflies, and Hampson states that they "mimic" the Papilios of the _Polyxenus_ group. Very little is known about these extremely rare Insects, but the larva is stated, on the authority of Mr. Dudgeon, to surpass the moths themselves in extravagance; to be covered with long processes of snow-white efflorescence, like wax, exuded from the skin, and to "mimic" a colony of the larva of a Homopterous Insect. Some ten species of this genus are known from Java, India, China, and Japan. In this family there is said to be a rudimentary frenulum, but it is doubtful whether the hairs that have given rise to this definition really justify it.

{419}FAM. 39. URANIIDAE.—A family of small extent, including light-bodied moths with ample wings and thread-like antennae; most of them resemble Geometridae, but a few genera, _Urania_ and _Nyctalemon_, are like Swallow-tail butterflies and have similar habits. The Madagascar moth, _Chrysiridia madagascariensis_ (better known as _Urania rhipheus_), is a most elegant and beautiful Insect, whose only close allies (except an East African congener) are the tropical American species of _Urania_, which were till recently treated as undoubtedly congeneric with the Madagascar moth. The family consists of but six genera and some sixty species. The question of its affinities has given rise to much discussion, but on the whole it would appear that these Insects are least ill-placed near Noctuidae.[316] The larva of the South American genus _Coronidia_ is in general form like a Noctuid larva, and has the normal number of legs; it possesses a few peculiar fleshy processes on the back. A description of the larva of _Chrysiridia madagascariensis_ has been widely spread; but according to Camboué,[317] the account of the metamorphoses, first given by Boisduval, is erroneous. The larva, it appears, resembles in general form that of _Coronidia_, and has sixteen feet; it is, however, armed with long, spatulate black hairs; it changes to a pupa in a cocoon of open network.

[Illustration: Fig. 206—Abdomen of _Chrysiridia madagascariensis_. A, Horizontal section showing the lower part of the male abdomen: 1, first segment; 2, spiracle of second segment; 4-8, posterior segments. B, the abdomen seen from the side, with the segments numbered. The section is that of an old, dried specimen.]

In all the species of this family we have examined, we have noticed the existence of a highly peculiar structure that seems hitherto to have escaped observation. On each side of the second abdominal segment there is an ear-like opening (usually {420}much concealed by overlapping scales), giving entrance to a chamber in the body; this chamber extends to the middle line, being separated from its fellow by only a thin partition. At its anterior and lateral part there is a second vesicle-like chamber, formed by a delicate membrane that extends as far forwards as the base of the abdomen. There can be little doubt that this is part of some kind of organ of sense, though it is much larger than is usual with Insect sense-organs.

FAM. 40. EPIPLEMIDAE.—Under this name Hampson has assembled certain Geometroid moths, some of them placed previously in Chalcosiidae, some in Geometridae. They form a varied group, apparently closely allied to Uraniidae, and having a similar peculiar sense-organ; but are distinguished by the presence of a frenulum. The larva seems to be like that of Uraniidae.

FAM. 41. PYRALIDAE.—This division is to be considered rather as a group of families than as a family; it includes a very large number of small or moderate-sized moths of fragile structure, frequently having long legs; antennae simple, only in a few cases pectinate; distinguished from Noctuidae and all the other extensive divisions of moths by the peculiar course of the costal nervure of the hind wing, which either keeps, in the middle of its course, near to the sub-costal or actually unites with it, subsequently again separating. Members of the Pyralidae are found in all lands; in Britain we have about 150 species. The larvae are usually nearly bare, with only short, scattered setae, and little coloration; they have most varied habits, are fond of concealment, and are very lively and abrupt in movement, wriggling backwards as well as forwards, when disturbed; a cocoon is formed for the metamorphosis.

The family as a whole consists of Insects of unattractive appearance, although it contains some very elegant and interesting moths and numerous forms of structural interest. In the genus _Thiridopteryx_ little transparent spaces on the wings occur as a character peculiar to the males; the spaces are correlative with a greater or less derangement of the wing-nervures. In some other forms there is a remarkable retinaculum, consisting of large scales, and this, too, is connected with a distortion of the wing-nervures. The Pyralidae—Pyralites of Ragonot,[318] Pyralidina of {421}Meyrick—have recently been revised by two naturalists of distinction almost simultaneously; unfortunately their results are discrepant, Meyrick including Pterophoridae and Orneodidae, and yet admitting in all only eight families; while Ragonot does not include the two groups named, but defines seventeen tribes of the two families—Pyralidae and Crambidae—that he admits.

The Pyraustidae of Meyrick is an enormous division including the Hydrocampidae and Scopariidae of many authors, as well as the Pyraustinae proper and a small group of Ragonot's, the Homophysinae. The division Scopariinae is believed to be amongst the "most ancient" of Lepidoptera; the food of the larvae consists of moss and lichens. This group is widely distributed, being richly represented in Australia, New Zealand, and the Hawaiian Islands, as well as in Europe; and probably really occurs wherever their food-plants exist accompanied by a tolerable climate. The statistics of the distribution of this group, so far as at present known, have been furnished by Mr. Meyrick, as follows:—European region, about 25 species; Madeira, 3; St. Helena, 6; South Africa, 2 or 3; India, 9; Malayan region, 3 or 4; Australia, 24; New Zealand, 64; Hawaiian Islands, 50; North America, 17 (one of them European); South America, 10. The Hydrocampinae—the China-marks—are of great interest, as being amongst the few forms of Lepidoptera adapted for aquatic life. It is believed that all their larvae are aquatic, though of only a few is there much known. The diversity amongst these forms is of considerable interest. The habits of _Hydrocampa nymphaeata_ were long since described by Réaumur, and have more recently been dealt with by Buckler,[319] W. Müller[320] and Prof. Miall.[321] Although there are some discrepancies in their accounts, due we believe to the observations being made at different periods of the life and under somewhat different circumstances, yet the account given by Müller is we feel no doubt substantially correct. The larvae when hatched mine in the leaves of a water-plant for a short time—thirty hours to three days according to Buckler—and are completely surrounded by water, which penetrates freely into their burrows; at this period the caterpillar breathes by its skin, the spiracles being very small, and the tubes leading from {422}them closed and functionless. After this brief period of mining life, the larva moults and then constructs a habitation by cutting a piece out of a leaf, and fastening it to the under side of another leaf; it is thus provided with a habitation, but it is one into which the water freely enters, and the respiratory apparatus remains in the state we have described. The Insect passes through several moults, and then hibernates in the water. On its revival in the spring a change occurs, and the larva constructs a portable, or we should rather say free, habitation out of two large pieces of leaf of lens-shape, fastened together at the edges; but the larva has some method of managing matters so that the water can be kept out of this house; thus the creature lives in air though immersed in the water. A correlative change occurs in the structure of the skin and tracheal system. The former becomes studded with prominent points that help to maintain a coat of air round the Insect, like dry velvet immersed in water; the spiracles are larger than they were, and they and the tracheal tubes are open. One or two moults take place and the creature then pupates. There is a good deal of discrepancy in the accounts of this period, and it seems probable that the pupa is sometimes aerial, sometimes aquatic. Buckler's account of the formation of the case shows that the larva first cuts off, by an ingenious process, one piece of leaf, leaving itself on this, as on a raft; this it guides to a leaf suitable for a second piece, gets the raft underneath, and fastens it with silk to the upper portion, and then severs this, leaving the construction free; afterwards the larva goes through a curious process of changing its position and working at the two extremities of the case, apparently with the object of making it all right as regards its capacity for including air and keeping out water. He believes that Réaumur was correct in his idea that the larva regulates the admission of air or of water to the case in conformity with its needs for respiration. Müller calls special attention to the great changes in habit and in the structure of the integument during the life of this larva; but the reader will gather from what we relate as to various terrestrial Lepidopterous larvae, that these phenomena are not very dissimilar from what frequently take place in the latter; a change of habits at some particular moult, accompanied by great changes in the integument, and even in the size of the stigmata, being of frequent occurrence.

{423}The larva of _Nymphula stagnata_, a close ally of _H. nymphaeata_, has aquatic habits of a somewhat similar but simpler nature; while _N._ (_Paraponyx_) _stratiotata_ is very different. This larva is provided with eight rows of tufts of flexible branchiae, occupying the position of the spots or setigerous warts usual in caterpillars, and reminding one of the spines of certain butterfly-larvae, though they are undoubtedly respiratory filaments. These caterpillars protect themselves by forming silken webs or cases, or by adopting the case of some other larva, and are in the habit of holding on by the anal claspers, and rapidly and energetically moving the anterior parts of the body in an undulating fashion. The spiracles exist, but are functionless. The pupa lives under water, and has no branchiae; but three of the pairs of abdominal spiracles are open, and project from the body. Müller informs us that in a Brazilian _Paraponyx_ these three pairs of spiracles were already large in the larva, though the other pairs were very small, or absent. He considers that the moth of this species descends beneath the water of a rapid stream, and fastens its eggs on the stems of plants therein. _Cataclysta lemnata_ lives in a case of silk with leaves of duckweed attached to it, or in a piece of a hollow stem of some aquatic plant; it is believed to breathe, like _H. nymphaeata_, at first by the integument and subsequently by open stigmata; but particulars as to how it obtains the requisite air-supply are not forthcoming: the aquatic pupa breathes by three large abdominal spiracles like _Paraponyx_.

Musotimidae[322] is a small group of two or three genera found in Australia and Polynesia; and the Tineodidae also consist of only two Australian genera. Siculodidae is likewise a small Antarctic group, placed by Meyrick in Pyralidina; but his view is not accepted by Snellen and Ragonot. Epipaschiinae (formerly treated as a separate family) and Endotrichiinae are, according to Meyrick, subdivisions of the family Pyralidae proper, an enormous group of more than 100 genera. The Chrysauginae consist chiefly of American forms, and have not been treated by Meyrick; some of this group have been classed with Tortricidae or Deltoidae on account of the undulating costa of the front wings and the long, peculiar palpi. The Galleriidae are a small group including Insects that live in bees'-nests, and feed on the wax {424}etc.; others eat seeds, or dried vegetable substances. Three out of our five British species of this family occur (usually gregariously) in bee-hives, and have the peculiar habit of spinning their cocoons together. The mass of common cocoons formed in this manner by _Aphomia sociella_ is remarkably tough and enduring; portions of it are not infrequently picked up, and as the cocoons are of a peculiar tubular form their nature gives rise to some perplexity.

Phycitidae[323] is another very large assemblage of Insects with very diverse habits. The frenulum and retinaculum are similarly formed in the two sexes: the males frequently have the basal-joint of the antennae swollen; hence the term "Knot-horns" applied by collectors to these moths. The larvae of the species of _Ephestia_ infest groceries, and most children have become to a slight extent acquainted with them amongst dried figs; that of _E. kuehniella_ has become very injurious in flour-mills, its enormous increase being due in all probability to the fact that the favourable and equable temperature maintained in the mills promotes a rapid succession of generations, so that the Insect may increase to such an extent as to entirely block the machinery. Many of the Phycitidae feed on the bark of trees in galleries or tunnels constructed partially of silk. A very peculiar modification of this habit in _Cecidipta excoecaria_ has been described by Berg.[324] In Argentina this Insect takes possession of the galls formed by a _Chermes_ on _Excoecaria biglandulosa_, a Euphorbiaceous tree. The female moth lays an egg on a gall, and the resulting larva bores into the gall and nourishes itself on the interior till all is eaten except a thin external coat; the caterpillar then pupates in this chamber. The galls vary in size and shape, and the larva displays much constructive ability in adapting its home to its needs by the addition of tubes of silk or by other modes. Sometimes the amount of food furnished by the interior of the gall is not sufficient; the larva, in such cases, resorts to the leaves of the plant for a supplement, but does not eat them in the usual manner of a caterpillar; it cuts off and carries a leaf to the entrance of its abode, fastens the leaf there with silk, and then itself entering, feeds, from the interior, on the food it has thus acquired. Another Phycitid, _Dakruma coccidivora_ is very {425}beneficial in North America by eating large Scale-Insects of the _Lecanium_ group, somewhat after the fashion of _Erastria scitula_; it does not construct a case, but shelters itself when walking from one scale to another by means of silken tubes; it suffers from the attacks of parasites.[325] Oxychirotinae, an Australian group, is interesting because, according to Meyrick, it possesses forms connecting the Pterophoridae with the more normal Pyralids.

Crambidae, or Grass-moths, are amongst the most abundant Lepidoptera in this country, as they include the little pale moths that fly for short distances amongst the grass of lawns and pastures; they fold their wings tightly to their body, and have a head pointed in front, in consequence of the form and direction of the palpi. They sit in an upright position on the stems of grass, and it has been said that this is done because then they are not conspicuous. Perhaps: but it would be a somewhat difficult acrobatic performance to sit with six legs across a stem of grass. The larvae are feeders on grass, and construct silken tunnels about the roots at or near the surface. The Ancylolominae are included in Crambidae by Meyrick and Hampson. Schoenobiinae[326] are included by Meyrick in Pyraustidae, but this view appears not to meet with acceptance, and the group is more usually associated with the Crambidae. Most writers place the anomalous genus _Acentropus_ as a separate tribe, but it is associated by both Meyrick and Hampson with _Schoenobius_. This Insect is apparently the most completely aquatic of all the Lepidoptera, and was for long associated with the Trichoptera in consequence of its habits and of the scaling of the wings being of a very inferior kind. The males may sometimes be found in large numbers fluttering over the surface of shallow, but large, bodies of water; the females are rarely seen, and in some cases have no wings, or have these organs so small as to be useless. The female, it would appear, comes quite to the surface for coupling, and then takes the male beneath the water. The larvae have the usual number of Lepidopterous feet, and apparently feed on the leaves of plants below water just as Lepidopterous larvae ordinarily do in the air.[327] They have no trace of gills, and their {426}mode of respiration is unknown. A great deal has been written about these Insects, but really very little is known. They are abundant, though local in many parts of North and Central Europe; some of the females have, as we have said, abbreviated wings, but how many species there are, and whether the modifications existing in the development of the wings are constant in one species or locality, are unknown as yet.

FAM. 42. PTEROPHORIDAE[328] (_Plume-moths_).—Elegant Insects of small size, usually with the wings divided (after the fashion of a hand into fingers) so as to form feathers: the extent of this division is diverse, but the hind wings are more completely divided than the front, which indeed are sometimes almost entire. The group is placed by Meyrick in his Pyralidina, but there are many entomologists who look on it as distinct. It consists of two sub-families, Agdistinae and Pterophorinae, that have been treated as families by many entomologists. The Agdistinae (of which we have a British representative of the only genus _Agdistes_) have the wings undivided. Pterophorinae have the hind wings trifid or (rarely) quadrifid, the front wings bifid or (rarely) trifid. The larvae of the Pterophorinae are different from those of Pyralidae, being slow in movement and of heavy form, covered with hair and living exposed on leaves; the pupae are highly remarkable, being soft, coloured somewhat like the larvae, and also hairy like the larvae, and are attached somewhat after the manner of butterfly-pupae by the cremaster: but in some cases there is a slight cocoon. There is, however, much variety in the larval and pupal habits of the Pterophoridae, many having habits of concealment of divers kinds. We have thirty species of these lovely Plume-moths in Britain. The family is widely distributed, and will probably prove numerous in species when the small and delicate Insects existing in the tropics are more appreciated by collectors.

FAM. 43. ALUCITIDAE (ORNEODIDAE of Meyrick and others).—The genus _Alucita_ includes the only moths that have the front and hind wings divided each into six feathers. Species of it, though not numerous, occur in various regions. The larva and pupa are less anomalous than those of the Pterophoridae, though the imago is more anomalous. The caterpillar of our British _A. polydactyla_ feeds on the flower-buds of honey-suckle, and forms a {427}cocoon. The moth with wings expanded is about an inch across, and is a lovely object. It is not rare, though seldom numerous.

FAM. 44. TORTRICIDAE.—Moths of small size, with a rather ample wing area, with the wing-fringes never as long as the wings are wide (long across), the hind wings without a pattern: the anterior nervure on the hind wings is simply divergent from that next to it, and the internal nervure, 1b, is very evidently forked at the base. The larvae inhabit their food, which may be rolled up or twisted leaves, or the interior of fruits and herbs, or galls, or even roots; they exhibit less diversity than is usual in other large series of moths; all have the normal complement of sixteen legs. This group is a very extensive one, but is much neglected owing to the great difficulties attending its study; it is not recognised in Hampson's Table of families given on p. 370, being there merged in Tineidae. It appears, however, to be a really natural group, and it is not desirable to merge it in the sufficiently enormous assemblage of the Tineidae till this has been shown to be necessary by the light of a greater knowledge of the external anatomy than we possess at present. The term Microlepidoptera is frequently met with in entomological literature, and should, we think, be confined to the two series Tortricidae and Tineidae. The Pterophoridae, and even the Pyralidae, have been, and still sometimes are, included under this term, but at present it seems best to limit its application as is here suggested.

Three great divisions are at present recognised; these were formerly called by Meyrick,[329] Tortricidae, Grapholithidae, Conchylidae; subsequently,[330] he has adopted the names Tortricidae, Epiblemidae, Phaloniadae. Lord Walsingham, who has devoted a great deal of time and study to the elucidation of this most difficult group, has suggested[331] that another change is desirable, and if so the nomenclature will be:—1. Tortricidae [or Tortricinae, according to the view that may be taken as to the group being family or sub-family]; 2. Phaloniidae [= the formerly used name, Conchylidae]; 3. Olethreutidae [= the formerly used name Grapholithinae = Epiblemidae, Meyr.]. We have upwards of 300 species in Britain, nearly 200 of which belong to the last division. The name Tortricidae refers to the habit the {428}larvae of these moths possess of rolling up leaves, or twisting and distorting shoots and buds.

The mode in which leaves and shoots are twisted and rolled by the very small larvae has been much discussed and is probably the result of two or three distinct causes:—1, the immediate operations of the larva; 2, the contraction of silk when drying; 3, changes in the mode of growth of the parts of the vegetable, resulting from the interference of the caterpillar. The larvae of this family that live in fruits are only too widely (we will not say well) known. Stainton gives as the habitat of _Epinotia funebrana_, "larva frequent in plum-pies"; the caterpillar of _Carpocapsa pomonella_ (the Codling-moth) mines in apples and pears, and its ravages are known only too well in widely distant parts of the world where fruit-trees of this kind are cultivated. _C. splendana_ lives in acorns and walnuts; _C. juliana_ in Spanish chestnuts. Two, if not more, larvae live in the seeds of Euphorbiaceous plants, and have become notorious under the name of jumping-beans, on account of the movements they cause. As these latter show no trace externally of being inhabited, the movements are supposed to be a mysterious property of the seed; they are really due to its containing a large cavity, extending, in one direction of the seed, nearly or quite from skin to skin; in this the larva makes a movement sufficient to alter the point of equilibrium of the quiescent seed, or as a free body to strike some part of it. The exact nature of the movements of the larva have not, we believe, been ascertained. There are, at least, two species of these Insects, and two plants harbouring them, known in the United States and Mexico, viz. _Carpocapsa saltitans_ living in the seeds of _Croton colliguaja_ and _Grapholitha sebastianiae_ living in the seeds of _Sebastiania bicapsularis_.

FAM. 45. TINEIDAE.—Small moths with the labial palpi more flexible and mobile than in other moths; usually separated and pointed. Hind wings frequently with very long fringes, the wing itself being proportionally reduced in size, and in consequence pointed at the tip. Larvae very diverse, almost always with habits of concealment. The series of forms included under this head is very numerous, the British species alone mounting up to 700, while the total described cannot be less than 4000. This number, however, must be but a fragment of what exists, if Mr. Meyrick be correct in supposing that a single one of the divisions of the family—Oecophoridae—comprises 2000 species in Australia and New Zealand alone.

{429}[Illustration: Fig. 207—_Diplosara lignivora_ (Gelechiides). Hawaiian Islands.]

As the study of these Insects is attended with great difficulty on account of their fragility and the minute size of the great majority, it is not a matter for surprise that their classification is in a comparatively rudimentary state. We shall not, therefore, deal with it here. Neither can we attempt to give any idea of the extreme diversity in the colours, forms, and attitudes of these small Insects. The one shown in Fig. 207, is remarkable on account of the great accumulation of scales on the wings and legs. As regards the pointed wings and the long fringes, we may remark that it is probable that in many of these small forms the wings are passive agents in locomotion; a similar condition of the wings is found in other very minute Insects, _e.g._ Thysanoptera and Trichopterygidae; in all these cases the framework of the wings is nearly absent: in some forms of the Tineidae, _Opostega_, e.g. the nervules are reduced to three or four in each wing. The variety in habits is as great as that of the external form, and the larvae exceed in diversity those of any other group of Lepidoptera. No doubt a corresponding amount of diversity will be discovered in the details of structure of the perfect Insects, the anatomy of but few having been at present investigated. _Tinea pellionella_ has two very important peculiarities in its internal anatomy: the testes consist of four round follicles on each side, and, contrary to the condition generally prevalent in Lepidoptera, are not brought together in a common capsule: the two groups are, however, not quite free (as they are in _Hepialus_), but are connected by a loose tracheal network. Even more remarkable is the fact also pointed out by Cholodkovsky[332] that the adult Insect possesses only two Malpighian tubes instead of six, the normal number in Lepidoptera; in the larva there are, however, six elongate tubes. The group of forms to which {430}_Tinea_ belongs is remarkable for the diversity and exceptional character of the food-habits of the larvae; species subsist on dried camel's dung, various kinds of clothes, furs, and hair, and even about horns of deer and horses' hoofs: one species has been found in abundance in the hair of a live sloth, _Bradypus cuculliger_, under circumstances that render it possible that the larva feeds on the creature's hair, though it may feed on minute vegetable matter found in the hair. The larva of _Tinea vastella_ is occasionally found feeding on the horns of living antelopes. Several species of Tineidae are known to devour Scale-Insects.

_Lita solanella_ is notorious for the ravages it commits on stored potatoes. Quite a number of species live on cryptogamic matter, or in old wood; _Oinophila v-flavum_ feeds on the mould on the walls of cellars, and is reputed to be injurious by occasionally also attacking the corks of bottles containing wine. _Oecocecis guyonella_ is said to be the cause of galls on _Limoniastrum guyonianum_, a plant that, growing in the deserts to the south of Algeria, is a favourite food of camels, and is frequently entirely covered with sand. The deposition of an egg by this moth is believed by Guénée[333] to give rise to a gall in which the larva is entirely enclosed (like the larvae of the gall-flies). Of Clothes-moths there are at least three species widely distributed. _Trichophaga tapetzella_ is perhaps entitled to be considered the Clothes-moth; its caterpillar not only feeds on clothes, but spins webs and galleries amongst them. _Tinea pellionella_ is also very common; its larva lives in a portable case, while that of the third species, _Tineola biselliella_, forms neither a case nor definite galleries. We have found this the most destructive of the three at Cambridge. Clothes or valuable furs may be completely protected by wrapping them in good sound paper in such a way that no crevices are left at the places where the edges of the paper meet. Garments that have become infested may be entirely cleared by free exposure to air and sunshine.

Two species of _Tinea_ have been recorded as viviparous, viz. _Tinea vivipara_ in Australia, and an undetermined species in South America. The species of the genus _Solenobia_—in which the female is apterous—are frequently parthenogenetic. The group Taleporiidae, to which this genus belongs, is by some {431}classified with Psychidae, in which family, as we have pointed out, one or two parthenogenetic forms are also known.

The larvae of Tineidae, though they do not exhibit the remarkable armature found in so many of the larger caterpillars, are exceedingly diverse.[334] Some are entirely destitute of feet (_Phyllocnistis_). Others are destitute of the thoracic legs; _Nepticula_ is in this case, but it is provided with an increased number of abdominal feet, in the form of more or less imperfect ventral processes. Some mine in leaves, others live in portable cases of various forms. Some are leaf-miners during their early life, and subsequently change their habits by constructing a portable case. The genus _Coleophora_ affords numerous instances of this mode of life; the habits of these case-bearers exhibit considerable variety, and there are many points of interest in their life-histories. Change of habit during the larval life has already been alluded to as occurring in many Lepidoptera and is nowhere more strikingly exemplified than in certain Tineidae. Meyrick mentions the following case as occurring in an Australian Insect, _Nematobola orthotricha_;[335] the larva, until two-thirds grown, is without feet, and is almost colourless, and mines in the leaves of _Persoonia lanceolata_; but when two-thirds grown it acquires sixteen feet, changes colour, becoming very variegate, and feeds externally, unprotected, on the leaves. The cases of the case-bearing Tineids are usually of small size, and do not attract attention like those of Psychidae. A very remarkable one was discovered by Mr. E. E. Green in Ceylon, and was at first believed to be formed by a Caddis-worm. It has now been ascertained that the Insect forming it is the caterpillar of _Pseudodoxia limulus_, a Tineid moth of the group Depressariidae;[336] the case is composed of minute fragments of moss, sand, and lichens; the anterior end is dilated into a shield-like hood that covers and protects the anterior parts of the larva when feeding; the food is mosses and lichens on rocks and trees. Before pupating, the larva folds down the edges of the hood over the mouth of the tube, like an envelope, fastening them with silk. The case is fixed to the rock or other support and hangs there until the moth appears.

{432}[Illustration: Fig. 208—_Pronuba synthetica_. North America. A, Larva; B, C, pupa, ventral and lateral aspects; D, female moth; E, head and part of thorax of the female moth: _a_, labial palp; _b_, maxillary tentacle; _c_, maxillary palp; _d_, proboscis; _e_, base of front leg. (After Riley.)]

The family Prodoxidae consists of some Tineids, the larvae of which feed in the pods and stems of the Yuccas of south-western North America; they have the mouth of very unusual form (Fig. 208, E), and some of them, by aid of this peculiar mouth, exhibit a remarkable modification of instinct. The facts are chiefly known from the observations of Riley[337] on _Pronuba yuccasella_, a moth living on _Yucca filamentosa_; this plant has been introduced into our gardens in this country, where it never, we believe, produces seed. The Yuccas are not fitted for self-fertilisation or for fertilisation by Insect agency of an ordinary kind. The progeny of the moth develops in the pods of the plant, and as these cannot grow until the flowers have been fertilised, the moth has the habit of fertilising the flowers at the time she lays her egg in the part that is to develop into the pod, and to be the food for her own progeny. The female moth first visits the stamens, and collects, by the aid of the {433}maxillae (which in this sex are very remarkably formed),[338] a considerable mass of pollen, which she holds by means of the peculiar maxillary tentacles; she then lays an egg in the pistil, usually of some flower other than that from which she has gathered the pollen; and after she has accomplished this act she carefully applies the pollen she had previously collected to the pistil, so as to secure the fertilisation of the flower and the development of the pod.

The species of _Prodoxus_ stand in a very peculiar relation to _Pronuba_. They also live in Yuccas, and have habits similar to those of _Pronuba_, with the important exception that, being destitute of the requisite apparatus, they do not fertilise the Yucca-flowers, and are thus dependent on _Pronuba_ for the steps being taken that are necessary for the rearing of the progeny of the two kinds of moth. Hence the name of Yucca-moth has been bestowed on _Pronuba_, and that of "bogus Yucca-moth" on the _Prodoxus_. The _Pronuba_ we figure is the largest and most remarkable species of the genus and fertilises _Yucca brevifolia_; the larva is destitute of abdominal feet, and in the pupa the spines on the back that exist in nearly all pupae that live in stems are developed to an extraordinary extent. The Yuccas do not flower every year, and the Prodoxidae have a corresponding uncertainty as to their periods of appearance, passing sometimes a year or two longer than usual in the pupal stage.

FAM. 46. ERIOCEPHALIDAE.—This family has recently been proposed for some of the moths formerly included in the genus _Micropteryx_.[339] They are small, brilliant, metallic Insects, of diurnal habits, but are very rarely seen on the wing, and it is doubtful whether they can fly much. These little Insects are of peculiar interest, inasmuch as they differ from the great majority of the Lepidoptera in at least two very important points, viz. the structure of the wings and of the mouth-parts. The mouth shows that we may consider that the Lepidoptera belong to the mandibulate Insects, although in the great majority of them the mandibles in the final instar are insignificant, functionless structures, or are entirely absent, and although the maxillae are so highly adapted for the tasting of sweets that it is difficult to recognise in them the parts usually found in the maxilla of mandibulate Insects.

{434}[Illustration: Fig. 209.—Larva of _Eriocephala calthella_. (After Chapman.) A, Young larva from side, × 50; B, portion of skin with a bulla or ball-like appendage: C, abdominal foot of larva.]

_Eriocephala_ in both these respects connects the Lepidoptera with Mandibulata: the mandibles have been shown by Walter[340] to be fairly well developed; and the maxillae are not developed into a proboscis, but have each two separate, differentiated—not elongated—lobes, and an elongate, five-jointed, very flexible palpus. The moths feed on pollen, and use their maxillae for the purpose, somewhat in the style we have mentioned in Prodoxidae. The wings have no frenulum, neither have they any shoulder, and they probably function as separate organs instead of as a united pair on each side: the modification of the anterior parts of the hind wing—whereby this wing is reduced as a flying agent to the condition of a subordinate to the front wing—does not here exist: the hind wing differs little from the front wing in consequence of the parts in front of the cell being well developed. There is a small jugum. These characters have led Packard to suggest that the Eriocephalidae should be separated from all other Lepidoptera to form a distinct sub-Order, Lepidoptera Laciniata.[341] The wing-characters of _Eriocephala_ are repeated—as to their main features—in Hepialidae and Micropterygidae; but both these groups differ from _Eriocephala_ as to the structure of the mouth-parts, and in their metamorphoses. Although _Eriocephala calthella_ is one of our most abundant moths, occurring in the spring nearly everywhere, and being easily found on account of its habit of sitting in buttercup-flowers, yet its metamorphoses were till recently completely unknown. Dr. Chapman has, however, been able to give us some information as to the habits and structure of the larvae, in both of which points the creature is most interesting. The eggs and young larvae are "quite {435}unlike our ideas of a Lepidopterous Insect;" the former have a snowy or mealy appearance, owing to a close coating of minute rods standing vertically on the surface of the egg, and often tipped with a small bulb. The larva lives amongst wet moss and feeds on the growing parts thereof; it is not very similar to any other Lepidopterous larva: Dr. Chapman suggests a similarity to the Slug-worms (Limacodids), but Dyar is probably correct in thinking the resemblances between the two are unimportant: the larva of _Eriocephala_ possesses three pairs of thoracic legs, and eight pairs of abdominal appendages, placed on the segments immediately following the thorax; on the under-surface of the ninth and tenth abdominal segments there is a sucker, trifoliate in form; this is probably really situate entirely on the tenth segment: the body bears rows of ball-appendages, and the integument is beautifully sculptured. The head is retractile and the antennae are longer than is usual in caterpillars. This larva is profoundly different from other Lepidopterous larvae inasmuch as the abdominal feet, or appendages, are placed on different segments to what is customary, and are of a different form. Unfortunately the pupa has not been procured, but there is some reason for supposing that it will prove to be more like that of Tineidae than like that of Micropterygidae.

The New Zealand genus _Palaeomicra_ is only imperfectly known. Meyrick considers it the "most ancient" Lepidopteron yet discovered; and it would appear that its relations are with _Eriocephala_ rather than with _Micropteryx_. From information he has kindly given to us, we are able to say that this moth possesses mandibles but no proboscis.

[Illustration: Fig. 210—Larva of _Micropteryx_ sp. A, Ventral view of the larva, magnified; B, the same, with setae unduly magnified. Britain.]

FAM. 47. MICROPTERYGIDAE.—Small moths of metallic colours, without mandibles, with elongate maxillary palpi: without frenulum: both wings with a complex system of wing-veins: on the hind wings the area anterior to the cell is large, and traversed by three or four elongate, parallel veins.

{436}[Illustration: Fig. 211—Pupa of _Micropteryx_ (_semipurpurella_?). A, Dorsal aspect; B, C, D, views of head dissected off; B, profile; C, posterior, D, anterior aspects; _m_, mandibles. Britain.]

There are no mandibles, but there is a short, imperfect proboscis. Larva (Fig. 210) without any legs, mining in leaves. The pupa (Fig. 211) is not a pupa obtecta, but has the head and appendages free, and is provided with enormous mandibles. Although these Insects in general appearance resemble _Eriocephala_ to such an extent that both have been placed in one genus, viz. _Micropteryx_, yet the two forms are radically distinct. The most remarkable point in _Micropteryx_ is the metamorphosis; the female moth is furnished with a cutting ovipositor, by the aid of which she deposits an egg between the two layers of a leaf after the manner of a saw-fly;[342] the larva mines the newly-opened leaves in the early spring, and feeds up with rapidity; it by some means reaches the ground, and there pupates in a firm but thin cocoon, with grains of earth fastened to it; in this it passes the greater part of its life as a larva, changing to a pupa very early in the following spring. The pupa is unlike any other Lepidopterous pupa, but is similar to those of Trichoptera; neither the head nor the appendages are glued to the body or to one another, but are free, so that the pupa can use the appendages to a considerable extent; it is furnished with enormous mandibles (Fig. 211, C, D), which are detached and shed after emergence.[343] In the interval between {437}the larval period of feeding and the imaginal instar, the phenomena of life are essentially like those of Trichoptera. The larva has not been at all satisfactorily studied; the spiracles appear to be excessively minute, but have been ascertained by Dr. Chapman to be normal in number and position.

All the information we possess points to profound distinctions between _Micropteryx_ and _Eriocephala_, for whereas in the former the mandibles drop off from the pupa, so that the imago has no mandibles, in the latter the mandibles exist, as they do in several other true Lepidoptera. As the history of the mandibles is not known in other Lepidoptera (where they are present in the larva but wanting in the imago), it is premature to conclude that no other Lepidoptera suffer the actual loss of the mandibles as _Micropteryx_ does, though there is nothing to lead us to believe that in any other Lepidopterous pupa are the mandibles specially developed as they are in _Micropteryx_. This pupa is in fact quite unique in this Order of Insects. When the history of the pupal mandibles is known, we shall be able to decide whether they are secondary structures, like the deciduous, supplementary mandibles found in Otiorhynchides (Coleoptera, Rhynchophora).

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