CHAPTER VIII

HEMIPTERA—OR BUGS

ORDER IX. HEMIPTERA.

_Mouth consisting of a proboscis or mobile beak (usually concealed by being bent under the body), appearing as a transversly-jointed rod or grooved sheath, in which are enclosed long slender setae (like horse-hairs). Wings (nearly always) four; the anterior frequently more horny than the posterior pair, and folding flat on the back, their apical portions usually more membranous than the base_ (Heteroptera); _or the four wings may cover the abdomen in a roof-like manner, and those of the anterior pair may not have the basal and apical parts of different consistences_ (Homoptera); _sometimes all four of the wings are transparent. The young resembles the adult in general form; the wings are developed outside the body, by growth, at the moults, of the sides of the hinder portions of the meso- and meta-notum; the metanotal prolongations being more or less concealed by the mesonotal._

The Hemiptera or Bugs are perhaps more widely known as Rhynchota. In deciding whether an Insect belongs to this Order the student will do well to examine in the first place the beak, treating the wings as subordinate in importance, their condition being much more variable than that of the beak. The above definition includes no reference to the degraded Anoplura or Lice. These are separately dealt with on p. 599; they are absolutely wingless, and have an unjointed proboscis not placed beneath the body, the greater part of it being usually withdrawn inside the body of the Insect.

The Hemiptera are without exception sucking Insects, and {533}the mouth-organs of the individual are of one form throughout its life. In this latter fact, coupled with another, that the young are not definitely different in form from the adult, Bugs differ widely from all other Insects with sucking-mouth. They agree with the Orthoptera in the facts that the mouth does not change its structure during the individual life, and that the development of the individual is gradual, its form, as a rule, changing but little. In respect of the structure of the mouth, Orthoptera and Hemiptera are the most different of all the Orders. Hence, Hemiptera is really the most isolated of all the Orders of Insects. We shall subsequently see that, like Orthoptera, the Order appeared in the Palaeozoic epoch. Although a very extensive Order, Hemiptera have for some incomprehensible reason never been favourite objects of study. Sixty years ago Dufour pointed out that they were the most neglected of all the great Orders of Insects, and this is still true; our acquaintance with their life-histories and morphology especially being very limited.

[Illustration: Fig. 255—_Eusthenes pratti_ (Pentatomidae). China. A, Nymph: _a_, case of anterior, _b_, of posterior wing; _c_, orifices of stink-glands; B, the adult Insect.]

There is probably no Order of Insects that is so directly connected with the welfare of the human race as the Hemiptera; indeed, if anything were to exterminate the enemies of Hemiptera, we ourselves should probably be starved in the course of a few months. The operations of Hemiptera, however, to a large extent escape observation, as their mouth-setae make merely pricks that do not attract notice in plants; hence, it is probable that {534}injuries really due to Hemiptera are frequently attributed to other causes.

In the course of the following brief sketch of the anatomy and development of Hemiptera, we shall frequently have to use the terms Heteroptera and Homoptera; we may therefore here mention that there are two great divisions of Hemiptera having but little connection, and known by the above names: the members of these two Sub-Orders may in most cases be distinguished by the condition of the wings, as mentioned in the definition at the commencement of this chapter.

EXTERNAL STRUCTURE.—The mouth-parts consist of an anterior or upper and a posterior or lower enwrapping part, and of the organs proper, which are four hair-like bodies, dilated at their bases and resting on a complex chitinous framework. The lower part forms by far the larger portion of the sheath and is of very diverse lengths, and from one to four-jointed: it is as it were an enwrapping organ, and a groove may be seen running along it, in addition to the evident cross-segmentation. The upper covering part is much smaller, and only fills a gap at the base of the sheath; it can readily be lifted so as to disclose the setae; these latter organs are fine, flexible, closely connected, rods, four in number, though often seeming to be only three, owing to the intimate union of the components of one of the two pairs; at their base the setae become broader, and are closely connected with some of the loops of the chitinous framework that is contained within the head. Sometimes the setae are much longer than the sheath; they are capable of protrusion. Although varying considerably in minor points, such as the lengths of the sheath and setae, and the number of cross-joints of the sheath, these structures are so far as is known constant throughout the Order. There are no palpi, and the only additions exceptionally present are a pair of small plates that in certain forms (aquatic family Belostomidae) lie on the front of the proboscis near the tip, overlapping, in fact, the last of the cross-articulations.

Simple as is this system of trophi its morphology is uncertain, and has given rise to much difference of interpretation. It may be granted that the two portions of the sheath are respectively upper lip, and labium; but as to the other parts wide difference of opinion still prevails. On the whole the view most generally accepted, to the effect that the inner pair of the setae correspond {535}in a broad sense with maxillae of mandibulate Insects, and the outer pair with mandibles, is probably correct. Mecznikow, who studied the embryology,[462] supports this view for Heteroptera, but he says (_t.c._ p. 462), that in Homoptera the parts of the embryo corresponding with rudimentary maxillae and mandibles disappear, and that the setae are subsequently produced from peculiar special bodies that are at first of a retort-shaped form; the neck of the retort becoming afterwards more elongate to form the seta; also that in the Heteropterous genus _Gerris_ the embryology in general resembles that of Homoptera, but the development of the setae is like that of other Heteroptera (_t.c._ p. 478). This discontinuity in the development of the Homopterous mouth has since been refuted by Witlaczil,[463] who found that the retort-shaped bodies really arise from the primary segmental appendages after they have sunk into the head. We are therefore justified in concluding that the mouth-parts are at first similarly developed in all Hemiptera, and that this development is of a very peculiar nature.

[Illustration: Fig. 256—Mouth-parts of Hemiptera. (After Wedde.) A, Section of the head and proboscis of _Pyrrhocoris apterus_: _dr_, gland; _i.g_, infra-oesophageal ganglion; _lb_, labium; _lr_, labrum; _m_, muscles; _m_^1 muscle (depressor of labium); _m_^2, muscle of syringe; _ph_, pharynx; _s_, setae; _s.g_, supra-oesophageal ganglion; _sp. dr_, salivary gland; _spr_, syringe: B, transverse section of proboscis of _Pentatoma rufipes_, at third joint of sheath: _m_, _m_, muscles; _md_, mandibular seta; _mx_, maxillary setae; _n_, nerve; _p_, the sheath or labium; _tr_, trachea.]

Smith is convinced that there are no traces of mandibular structure in any Hemiptera.[464] On the other hand, numerous entomologists have supposed they could homologise satisfactorily various parts of the Hemipterous trophi with special parts of the {536}maxillae and labium of mandibulate Insects. This point has recently been discussed by Marlatt[465] and by Heymons.[466] From the latter we gather that the mode of growth is peculiar by the extension backwards of some of the sclerites, and their becoming confounded with parts of the wall of the head. From all this it appears that at present we cannot correctly go farther than saying that the trophi of Hemiptera are the appendages of three head-segments, like those of other Insects. The views of Savigny, Léon,[467] and others to the effect that labial palpi, and even other parts of the labium of Mandibulata can be satisfactorily identified are not confirmed by Heymons.

Underneath the pharynx, in the head, there is a peculiar structure for which we have as yet no English term. It was apparently discovered by Landois and Paul Mayer,[468] and has been called "Wanzenspritze," which we translate as syringe. It may be briefly described as a chamber, into which the salivary ducts open, prolonged in front to the neighbourhood of the grooves of the setae in the rostrum; behind, it is connected with muscles; it has no direct connection with the pharynx, and though it was formerly supposed to be an organ of suction, it seems more probable that it is of the nature of a force-pump, to propel the products of some of the bug's glands towards the tips of the setae.

The rostrum being extended from its position of repose, the tip of the sheath is brought into contact with the object to be pierced, the surface of which is probably examined by means of sensitive hairs at the extremity of the sheath; these therefore functionally replace to some extent the palpi of other Insects. As a rule the sheath does not penetrate (though there is reason for believing that in various of the animal-feeding bugs it does so), but the setae are brought into action for piercing the skin of the plant; they are extremely sharp, and the outer pair are usually barbed, so that when once introduced a hold is easily maintained. This being established it is thought that the salivary pump comes into play, and that a fluid is injected into the object pierced so as to give rise to irritation or congestion, and thus keep up a supply of fluid at the point operated on: this fluid extends along the grooved setae by capillary attraction, and the {537}rapidity of the current is increased by a pumping

## action of the pharynx, and possibly by movements of the setae themselves.

Though the setae are often extremely elongate—sometimes several times the length of the body—they are nearly always slender, and there is no reason to suppose that a perfect, or air-tight, tube is formed; hence it is probable that capillary attraction is really the chief agent in the ingestion of the fluid. The slight diversity of structure of the Hemipterous trophi is in very striking contrast with what we find in mandibulate Insects, and in the less purely suctorial Insects, such as Diptera and some divisions of Hymenoptera. Schiödte in commenting on this has suggested that it is probably due to the small variety of actions the rostrum is put to.[469]

[Illustration: Fig. 257—_Saccoderes tuberculatus_ Gray. Brazil. (Fam. Reduviidae.) (Antennae absent in the specimen represented.)]

The head exhibits great variety of form; in the Homoptera the front part is deflexed and inflexed, so that it is placed on the under surface, and its anterior margin is directed backwards; it is often peculiarly inflated; in the Lantern-flies or Fulgoridae (Fig. 282) to an incomprehensible extent. In the great Water-bugs, Belostomidae, there is on the under surface a deep pocket for each antenna, beautifully adapted to the shape of the curiously-formed appendage (Fig. 279). The prothorax is always very distinct, frequently large, and in many of the Heteroptera (Fig. 257), as well as in the Homopterous family, Membracidae (Fig. 283), assumes the most extraordinary shapes. Both meso- and meta-thorax are well developed. The former is remarkable for the great size of the scutellum; in some cases (Plataspides, Scutellerides) this forms a large process, {538}that entirely covers and conceals the alar organs, so that the Insect has all the appearance of being apterous. The exact composition of the abdomen has not been satisfactorily determined, opinions varying as to whether the segments are nine, ten, or eleven in number. The difficulty of determining the point is due to two facts: viz. the extreme modification of the terminal segments in connection with the genital appendages, and the prominence of the extremity of the alimentary canal. If this terminal projection is to be treated as a segment, it would appear that eleven segments exist, at any rate in some cases; as the writer has counted ten distinct segments in a young Coreid bug, in addition to the terminal tube. This tube in some of the male Heteroptera is very subject to curious modifications, and has been called the rectal cauda. Verhoeff considers that ten segments were invariably present in the females examined by him in various families of Heteroptera and Homoptera.[470] In Aphidae (a division of Homoptera), Balbiani considers there are eleven abdominal segments present; but he treats as a segment a projection, called the cauda, situate over the anus; this structure does not appear to be homologous with the rectal cauda we have just mentioned. In Coccidae the number of abdominal segments is apparently reduced. Schiödte states[471] that the older authorities are correct in respect of the stigmata; there are, he says, in Heteroptera invariably ten pairs; one for each thoracic segment; and seven abdominal, placed on the ventral face of the pleural fold of the abdomen. In some cases there are additional orifices on the external surface that have been taken for stigmata, though they are really orifices of odoriferous glands; these openings may exist on the metasterna or on the dorsal surface of the abdomen. The lateral margins of the abdomen are frequently greatly developed in Heteroptera, and are called "connexivum;" the upper and lower surfaces of the body meeting together far within the marginal outline. Dr Anton Dohrn many years ago[472] called attention to the extremely remarkable structure of the terminal segments in many male Hemiptera; and the subject has been subsequently very imperfectly treated by the present writer and other entomologists, but it has never received the attention it deserves.

{539}In the females of numerous Heteroptera and Homoptera (Capsidae, Cicadidae, etc.) there is a well-developed ovipositor, that serves both as a cutting instrument to make slits in the stems of plants, and as a director to introduce the eggs therein. Verhoeff considers that it always consists of two pairs of processes (though one pair may be very small), one from the eighth abdominal segment, the other from the ninth.[473]

The antennae usually have very few joints, often as few as four or five, their maximum number of about twenty-five being attained in the males of some Coccidae, this condition being, however, present in but few of even this family. In _Belostoma_ (Fig. 279) they assume extremely curious forms, analogous to what we find in the Coleopterous genus _Hydrophilus_. In addition to the compound eyes, there are usually ocelli, either two or three in number, but wanting in many cases. The usual number of joints of the tarsi is three, but in Coccidae there is only one joint.

[Illustration: Fig. 258.—Alar organs of a Capsid bug (_Capsus laniarius_). A, Elytron: A, clavus; B, corium; C, cuneus; D, membrane; E, E, cell of the membrane; B, hind-wing.]

The wings (Fig. 258) exhibit much diversity. The anterior pair usually differ greatly from the posterior; they are called elytra, hemi-elytra or tegmina. This difference in the two pairs is the rule in the first of the great divisions of the Order, and the name Heteroptera is derived from the fact. In this Sub-Order the front wings close over the back, and are more or less horny, the apical part being, however, membranous. Systematists make use of the wings for the purpose of classification in Heteroptera, and distinguish the following parts, "clavus," "corium," "membrane," the corium being the larger horny division, the clavus the part lying next the scutellum and frequently very sharply distinguished from the corium; the membrane is the apical part. The outer or costal part of the wing is also often sharply delimited, and is called the "embolium;" in the great family Capsidae and a few others, the outer apical part of the {540}corium is differentiated from the rest of the surface, and is termed the "cuneus." In Plataspides, one of the divisions in which the alar organs are entirely covered by the scutellum, they are modified in a very remarkable manner. In the Homoptera the divisions named above do not exist, and the wings in repose are placed in a different position, as stated in our definition of the Order. It is said to be very difficult to homologise the wing-nervures of Hemiptera, and nothing appears to be known as to the mode of their development.

The alar organs in Hemiptera exhibit a very frequent form of variation within the limits of the same species; this has not yet been elucidated.[474] In some cases in the Heteroptera nearly all the individuals of a generation may have the wings aborted; sometimes this occurs as a local variation. In Aphidae the occurrence of winged and wingless individuals is very common, and has even become an important factor in their extraordinary life cycles. (See _Chermes_, etc., subsequently.)

INTERNAL ANATOMY.—The alimentary canal presents considerable diversity and some remarkable features. There is a slender tube-like oesophagus and a large crop. It is difficult to assign any of the parts posterior to this to the divisions usual in other Insects, and it is said that the distinction of parts histologically is as vague as it is anatomically. In the Heteroptera the Malpighian tubes open into two (or one) vesicular dilatations seated immediately in front of the short rectum: between this point and the crop there may be a very elongate, slender portion with one or more dilatations, these parts apparently replacing the true or chylific stomach. There is no gizzard. In the Homoptera the relations of the divisions of the alimentary canal are even more puzzling; the canal is elongated and forms coils, and these are connected with tissues and tunics so as to make their dissection extremely difficult. List says that there are great differences in the alimentary canal among the members of the one family Coccidae. There are usually four Malpighian tubes, but in Coccidae there is only one pair, and in Aphidae none. The excretory cells of these tubes are in Hemiptera of remarkably large size. There is a large development of salivary glands, at least two pairs existing. There can be little doubt that some of their products are used for purposes of injection, as {541}already described, though Künckel came to the conclusion that the saliva when placed in living plants is totally innocuous.[475]

The ganglia of the nervous system are all concentrated in the thorax and head. In some cases (in various Homoptera) the infra-oesophageal ganglion is placed at a distance from the supra-oesophageal ganglion, and may even be united with the thoracic mass of ganglia (_Orthezia_, etc.); in this case the chitinous framework of the mouth-parts is interposed between the supra- and the infra-oesophageal ganglia. In _Pentatoma_ all the three ganglionic masses are brought into close proximity, but in _Nepa_ the thoracic mass of ganglia and the infra-oesophageal ganglion are widely separated.

The ovarian tubes vary greatly in number: according to List in _Orthezia cataphracta_ the number differs considerably in different individuals, and even in the two ovaries of the same individual, the number being usually two. The testes are not placed in a common tunic, though they are frequently approximated or even contiguous.[476]

The smell of bugs is notorious. In many species it is not unpleasant, though as a rule it is decidedly offensive. It is a remarkable fact that the structures connected with the production of this odour are different in many cases in the young and in the adult. The odour emitted by the latter proceeds from a sac seated at the base of the abdomen, and opening exteriorly by means of an orifice on each side of the metasternum; while in the young there are two glands situated more dorsally and a little more backwards, and opening on two of the dorsal plates of the abdomen (Fig. 255, A).[477] In the young the dorsum of the abdomen, where the stink-glands open, is exposed, but this part in the adult is covered by the wings. The odorific apparatus is specially characteristic of Heteroptera, and Künckel states that there is so much variety that generic and even specific characters might be drawn from conditions of the stink-glands. As a rule they are most constantly present in the plant-feeding forms; in some essentially carnivorous forms (Reduviidae, Nepidae, {542}Notonectidae) they are entirely absent. The offensive matter emitted by _Notonecta_ is of a different nature, and is probably anal in origin.

METAMORPHOSIS OR POSTEMBRYONIC DEVELOPMENT.—In the language of the systematists of metamorphosis, Hemiptera are said to be Homomorpha Paurometabola—that is, the young differ but little from the adult. According to Brauer's generalisations they are Menorhynchous, Oligonephrous, Pterygogenea, _i.e._ they have a sucking mouth that does not change during life, few Malpighian tubes, and are winged in the adult state. It is generally admitted that the Homoptera do not completely agree with Heteroptera in respect of the metamorphosis, it being more marked in the former, and in Coccidae attaining (as we shall mention when discussing that family) nearly if not quite the condition of complete metamorphosis of a peculiar kind. Unfortunately we are in almost complete ignorance as to the details of the life-histories and development of Heteroptera, so that we can form no generalised opinion as to what the post-embryonic development really is in them, but there are grounds for supposing that considerable changes take place, and that these are chiefly concentrated on the last ecdysis. The young of some bugs bear but little resemblance to the adult; the magnificently-coloured species of _Eusthenes_ (Fig. 255), before they attain the adult condition are flat, colourless objects, almost as thin as a playing-card; it is well known that the extraordinary structures that cover and conceal the body in Plataspides, Scutellerides, Membracides, etc., are developed almost entirely at the last moult: it is not so well known that some of these changes occur with much rapidity. A very interesting account of the processes of colour-change, as occurring in _Poecilocapsus lineatus_ at the last ecdysis, has been given by Lintner,[478] and from this it appears that the characteristic coloration of the imago is entirely developed in the course of about two hours, forming a parallel in this respect with Odonata. When we come to deal with Aphidae we shall describe the most complex examples of cycles of generations that exist in the whole of the animal kingdom.

FOSSIL HEMIPTERA.—Hemiptera are believed to have existed in the Palaeozoic epoch, but the fossils are not numerous, and opinions differ concerning them. _Eugereon hockingi_, a {543}Permian fossil, was formerly supposed to be a Homopterous Insect, but it is very anomalous, and its claim to a position in Hemiptera is denied by Brauer,[479] who considers it to be Orthopterous. It is now generally recognised that this fossil requires complete reconsideration. Another Permian fossil, _Fulgorina_, is admitted to be Homopterous by Scudder, Brauer and Brongniart. Scudder thinks the Carboniferous _Phthanocoris_ was an Archaic Heteropterous Insect, and if correct this would demonstrate that both of the two great Sub-Orders of Hemiptera existed in Palaeozoic times. Brauer, however, is inclined to refer this fossil to Homoptera, and Brongniart[480] speaks of it as being without doubt a Fulgorid. _Dictyocicada_, _Rhipidioptera_ and _Meganostoma_, from the Carboniferous shales of Commentry, have also been referred to Fulgoridae by Brongniart, but the evidence of their alliance with this group is far from satisfactory. In the Secondary epoch numerous Hemiptera existed, and are referred to several of the existing families. They come chiefly from the Oolite. In the Eocene of the Isle of Wight a fossil has been discovered that is referred to the existing Homopterous genus _Triecphora_.

We are not entitled to conclude more from these facts than that Homoptera probably appeared before Heteroptera, and date back as far as the Carboniferous epoch.

CLASSIFICATION AND FAMILIES.—No complete catalogue of Hemiptera exists, but one by M. Severin is in course of publication. It is probable that there are about 18,000 species at present described, two-thirds of this number being Heteroptera. In Britain we have about 430 species of Heteroptera and 600 of Homoptera. The classification of the Order is not in a very advanced condition. The following table exhibits the views of Schiödte[481] in a modified form:—

Front of head not touching the coxae. I. Heteroptera. Front of head much inflexed so as to be in contact with the coxae. II. Homoptera.

Sub-Order I. Heteroptera.

Posterior coxae nearly globose, partly embedded in cavities, and having a rotatory movement. Mostly terrestrial forms. 1. Trochalopoda.

Posterior coxae not globose, larger, and not embedded; their articulation with sternum almost hinge-like. Posterior aspect of hind femur usually more or less modified for the reception of the tibia when closed on{544} it: mostly aquatic forms. 2. Pagiopoda.

Division 1. Trochalopoda.

This division includes the majority of the families of Heteroptera—viz. the whole of the terrestrial families except Saldidae, and it also includes Nepidae, a family of water-bugs.

Division 2. Pagiopoda.

This includes the six purely aquatic families of Heteroptera, except Nepidae, which appear to have very little connection with the other aquatic bugs. The only terrestrial Insects included in the family are the Saldidae; in these the femora are not modified as they are in the aquatic forms. Hemiptera that live on the surface of water, not in the water, are classed with the terrestrial species. With these exceptions this arrangement agrees with that of GYMNOCERATA and CRYPTOCERATA as usually adopted,[482] and therefore followed in the following pages. Schiödte's characters, moreover, do not divide his two divisions at all sharply.

Sub-Order II. Homoptera.

Tarsi usually three-jointed Series Trimera. " " two-jointed " Dimera. " " of one joint " Monomera.

The classification of Homoptera is in a most unsatisfactory state;[483] no two authors are agreed as to the families to be adopted in the series Trimera. We have recognised only five—viz. Cicadidae, Fulgoridae, Membracidae, Cercopidae, and Jassidae. The Dimera consists of Psyllidae, Aphidae, Aleurodidae; and the Monomera of Coccidae only. It is usual to associate the Dimera and Monomera together under the name of either Phytophthires or Sternorhyncha, but no satisfactory definition can be given of these larger groups, though it seems probable that the families of which they are composed are natural and distinct.

Sub-Order I. HETEROPTERA.

SERIES 1. GYMNOCERATA.

The majority of the terrestrial families of Heteroptera form the series Gymnocerata, in which the antennae are conspicuous, and can be moved about freely in front of the head, while in {545}Cryptocerata they are hidden. The series Gymnocerata includes all the terrestrial Heteroptera, and the two families, Hebridae and Hydrometridae, which live on the surface of the water or in very damp places; while Cryptocerata includes all the forms that live under water.

[Illustration: Fig. 259—_Phloea corticata._ South America.]

FAM. 1. PENTATOMIDAE.—_Scutellum very large, at least half as long as the abdomen, often covering the whole of the after-body and alar appendages. Antennae often five-jointed. Proboscis-sheath four-jointed. Ocelli two. Each tarsal claw with an appendage._—This, the largest and most important family of the Heteroptera, includes upwards of 4000 species, and an immense variety of forms. It is divided into no less than fourteen sub-families. The species of one of these, Plataspides, are remarkable for their short, broad forms, and the peculiar condition of the alar organs, which are so completely concealed by the great scutellum that it is difficult to believe the Insects are not entirely apterous. The head is usually inconspicuous though broad, but in a few forms it is armed with horns. Though this sub-family includes upwards of 200 species, and is very widely distributed in the Old World, it has no representatives in America. The Scutellerides also have the body covered by the scutellum, but their organs of flight are less peculiar than they are in the Plataspides; the Insects of this sub-family are highly remarkable on account of their varied and frequently vivid coloration; some of them are metallic, and the colour of their integuments differs greatly in some cases, according to whether the specimen is wet or dry; hence the appearance after death is often very different from that of the living specimen. These Insects are extremely numerous in species. The sub-family Phloeides (Fig. 259), on the contrary, includes only three or four South American species: they have no resemblance at all to other Pentatomidae; they are flat, about an inch long, and look like scales of bark, in this respect agreeing with _Ledra_ and some other Homoptera. The South American sub-family Cyrtocorides (Fig. 260) is of {546}equally small extent; the species are of strange irregular shapes, for which we can find no reason. The Tessaratomides includes many of the largest Hemiptera-Heteroptera, some of its members attaining two inches in length.

The great family Pentatomidae, containing about 400 species, is represented in Britain by about 36 native species, the most interesting of which are perhaps those of the genus _Acanthosoma_. De Geer noticed long ago that the female of _A. griseum_ exhibits great solicitude for its young, and his statement has since been confirmed by Mr. Parfitt and the Rev. J. Hellins, who found that the mother not only protects the eggs but also the young, and that for a considerable time after hatching.[484]

[Illustration: Fig. 260—_Cyrtocoris monstrosus._ South America, × 3.]

Very little is known as to the life-histories of Pentatomidae. In some cases the young are very different in appearance from the adults. The peculiar great scutellum is not developed till the mature condition is reached. But little attention has been given to the habits of Pentatomidae; it is generally considered that they draw their nutriment from plants; the American _Euthyrhynchus floridanus_ has, however, been noticed to suck the honey-bee, and we think it probable that a good many Pentatomids will be found to attack Insects.

The term Pentatomidae as applied to this family is of modern origin: in most books the equivalent group is called Scutata, or Scutati, and the term Pentatomidae is restricted in these works to the sub-family called Pentatomides in the system we adopt.

FAM. 2. COREIDAE.—_Scutellum not reaching to the middle of the body; proboscis-sheath four-jointed; ocelli present; antennae generally elongate and four-jointed, inserted on the upper parts of the sides of the head; femora not knobbed at the tip._—The members of this great family are easily recognised by the above characters; formerly it was called Supericornia in connection with the characteristic position of the antennae. About 1500 species are known, and they are arranged in no less than twenty-nine sub-families. Many of them are Insects of large size, and they frequently have a conspicuous disc, or dilatation, on one of the joints of the antennae.

{547}[Illustration: Fig. 261.—_Diactor bilineatus._ South America. × 3/2.

Fig. 262—_Phyllomorpha laciniata_, carrying some of its eggs. Spain.]

Another very curious and, as yet, inexplicable peculiarity very commonly met with among them, is that the hind legs may be of great size and deformed; either the femora or the tibiae, or both, being very much distorted or armed with projections. Brilliant colour is here comparatively rare, the general tone being indefinite tints of browns, greys, or smoky colours. The South American genus _Holymenia_ (_Copius_ of older authors) consists of slender forms, having the elytra transparent even on the basal

## part like Homoptera; this and some other peculiarities give the species of

this genus a certain resemblance to Insects of other Orders; Westwood says that _Diateina holymenoides_ (Diptera) greatly resembles a bug of the genus _Holymenia_. The tropical American genus _Diactor_ consists of a few species of elegant colour having the hind legs very peculiarly shaped, the tibiae being flattened and expanded in a sail-like manner, and ornamented with agreeable colours different {548}from those on the rest of the body; they are made more conspicuous by the femora being remarkably long and thin; it is probable that they are used as ornaments. The subfamily Phyllomorphides consists of about a dozen species, and is found in several of the western parts of the Eastern hemisphere, one species, _P. laciniata_, occurring in Southern Europe. This Insect is of very delicate texture, and the sides of the body are directed upwards and deeply divided so that a sort of basin is formed, of which the dorsum of the body is the floor; the Insect is very spinose, and is thus enabled to carry its eggs, the spines helping to retain them in position on the back. It is said to be the male that thus carries the eggs. This species is able to stridulate, and when doing so vibrates its antennae with excessive rapidity. We have only about a score of species of Coreidae in Britain, and none of the remarkable forms of the family are among them.

FAM. 3. BERYTIDAE.—_Very slender Insects with the first joint of the antennae and the femora thickened at the tips._—This small family was not distinguished from Coreidae by the older authors. It consists of about fifty species, eight of which are found in Britain.

FAM. 4. LYGAEIDAE.—_The characters are the same as those mentioned for Coreidae, except as regards the insertion of the antennae; the upper surface or face of the head is not so flat, but is transversely convex, so that seen in profile the antennae appear to be inserted well down on the sides of the head._—The name Infericornia was formerly applied to these Insects. They are on the average of smaller size than the members of the Coreidae or Pentatomidae, and are much less conspicuous in colour and form; a good many of the larger Lygaeids are, however, variegate with black, yellow, and red. The family is very numerous in species, about 1400 being known; they are arranged in thirteen sub-families; we have about sixty species in Britain, nearly all small. _Eremocoris_ lives, when immature, in the nests of the wood-ant, according to Wasmann. The family includes some notorious Insect-pests. The Chinch-bug, _Blissus leucopterus_, commits very serious ravages on corn and grasses in North America. The Cotton-stainer, _Dysdercus suturellus_ is also very injurious to cotton in certain parts of the New World: its growth has been described by Riley,[485] who thinks a dye valuable for {549}commercial purposes might be procured from the Insect. This bug has recently developed the habit of sucking oranges, and has thus become injurious in Florida, as the fruit readily decays after it has been punctured by these Insects. The phenomenon of "micropterism" is exhibited by numerous Lygaeids, as well as by Pyrrhocoridae.

FAM. 5. PYRRHOCORIDAE.—_Distinguished from Lygaeidae only by the absence of ocelli_, and not recognised as a distinct family by all Hemipterists. About 300 species are included. Our only British member is the notorious _Pyrrhocoris apterus_; it is, however, very rare in this country, though it abounds on the Continent, and has been the object of investigation by embryologists and others. It displays in a most marked manner the curious dimorphism as to the alar organs that is so common in certain divisions of Hemiptera; the elytra and wings being sometimes normally developed, while in other cases the wings are entirely absent, and the horny, basal part of the elytra only is present. In some localities, and in some years, only the micropterous form is found, while on other occasions there may be a large percentage of the macropterous form. The abundance of this Insect has enabled the French chemist Physalix to obtain an amount of its colouring matter sufficient for analysis; as the result he procured a substance, insoluble in water, very closely allied to carotine.[486] The Oriental Insect _Lohita grandis_ is one of the most remarkable of Bugs, the male of the Sumatran variety being over two inches in length, having enormously long antennae, and the abdomen extended to about twice the normal length, while the other sex is in the usual condition in these respects. The species is said to be injurious to the cotton-plant in India.

FAM. 6. TINGIDAE.—_Tarsi two-jointed. Elytra more or less reticulate, consisting of strong, irregular, thick lines forming a framework of cells, the enclosed part of the cell being of different texture and frequently transparent; antennae with terminal joint more or less knob-like, the preceding joint very long; ocelli wanting; pronotum prolonged behind, covering the scutellum; front coxae placed at the lack of the thorax._—This is the first of a series of families with only two joints to the feet. These little bugs are very remarkable objects, and exhibit much variety in their peculiar {550}sculpture, which in numerous forms attains a condition of elegance well worthy of attention. There are nearly 300 species known, and in Britain we have about a score. The characters we have given above do not apply to the genus _Piesma_, though it is usually placed in this family; its scutellum is not covered, and ocelli are present. Although but little is known as to the nature of the lives of Tingidae, yet it was pointed out long ago by Réaumur that a species of the family (probably _C. clavicorne_, Fig. 263), lives in deformations of the flowers of the Labiate plant now called _Teucrium chamaedrys_; Frauenfeld has more recently confirmed this observation, and shown that the closely allied _C. teucrii_ affects the flowers of _T. montanum_ in a similar manner.[487]

[Illustration: Fig. 263—_Copium clavicorne._ Europe. (After Rübsaamen.)]

[Illustration: Fig. 264—_Aradus orientalis._ Siam.]

FAM. 7. ARADIDAE.—_Very flat, broad; scutellum exposed, large or moderate; abdomen broader than the alar organs, which it frequently encases like a broad frame. Front coxae placed in the middle of the prosternum._—These very flat Insects, of obscure colour, have frequently very peculiar sculpture. They live under bark, or on fungi growing from bark, and are supposed to draw their nutriment from the fungi, though but little is actually known as to their natural history. The family is almost cosmopolitan, and includes about 300 species, of which five occur in England. The small sub-family Isoderminae consists of a few species that are placed only provisionally in Aradidae; they differ from the normal members by there being no groove on the {551}breast, so that the rostrum is free. Of the five species, three occur in Chili and Patagonia, two in Tasmania, and one in Australia.

FAM. 8. HEBRIDAE.—_Minute bugs, of semiaquatic habits, clothed beneath with a dense, minute, silvery pubescence; antennae five-jointed; legs of not more than average length; elytra in larger part membranous._—This small family consists altogether of only about a dozen species; we have two species of the genus _Hebrus_ in Britain; they are usually found in very wet moss.

[Illustration: Fig. 265.—_Halobates sobrinus._ Under surface of a female carrying eggs. Pacific Ocean (Marquesas).]

FAM. 9. HYDROMETRIDAE.—_Form very diverse; antennae four-jointed, tarsi two-jointed. Coxae usually widely separated. Either wingless or with elytra of one texture throughout, having no membranous part. Under surface with a minute velvet-like pubescence. In many forms the legs are of great length._—Although of comparatively small extent—scarcely 200 species being at present known—this family is of great interest from the habit possessed by its members of living on the surface of water. In the case of the notorious genus _Halobates_ (Fig. 265) the Insects can even successfully defy the terrors of Neptune and live on the ocean many hundreds of miles from land. There is great variety of form among Hydrometridae. The European and British genus _Mesovelia_ is of short form, and but little dissimilar from ordinary land-bugs, with which, indeed, it is connected by means of the genus _Hebrus_, already noticed. _Mesovelia_ represents the sub-family Mesoveliides, which, though consisting of only four species, occurs in both hemispheres, and in the tropics as well as in the temperate regions. Our species, _M. furcata_, walks on the surface of the water, the movements of its legs and the position of its coxae being those of land-bugs. Another British Insect—the highly remarkable _Hydrometra stagnorum_—is of excessively slender form, with long thin legs, by aid of which it {552}walks on the surface-film of water, above which its body is held well separated. It is easily drowned, and if submerged it has great difficulty in escaping from the water. This genus represents the sub-family Hydrometrides, and is apparently almost cosmopolitan. _Velia currens_ is another common British Insect; it loves the eddies and currents of backwaters on burns and streams, and is very abundant in Scotland. An American ally, _Rhagovelia plumbea_, appears to be not uncommon on the surface of the ocean in the Gulf of Mexico, near the shores. The great majority of the family belong to the division Gerrides, of which the curious, long Insects that float so lazily and skim so easily on the surface of quiet streams are typical. The species of the genus now called _Gerris_, but formerly known as _Hydrometra_ are apparently distributed all over the world; we have ten in Britain. They have very long legs, and on being alarmed move away with the greatest ease.

The genus _Halobates_ includes at present fifteen species. They are found on the ocean, where the surface-water is warm, in various parts of the world. They are destitute of any trace of alar organs, the meso- and meta-thorax are closely united and large, while the abdomen is very small, so that the body is of oval form; the middle legs are thrown so far back that they are placed immediately over the posterior pair. When the sea is calm these Insects skim over the surface with rapidity, but disappear as soon as it becomes agitated. They are believed to feed on small animals recently deceased; Witlaczil says on the juices of jelly-fish. The young are frequently met with, and there can be no doubt that the whole life-cycle may be passed through by the Insect far away from land. The Italian ship _Vettor Pisani_ met with a bird's feather floating on the ocean off the Galapagos Islands, covered with eggs which proved to be those of _Halobates_ in an advanced stage of development. It was formerly believed that the female carries the eggs for some time after their exclusion, and although this has since been denied, it is nevertheless an undoubted fact, for it was observed by Mr. J. J. Walker,[488] to whom we are indebted for a specimen having the eggs still attached to the body, as shown in Fig. 265. Mr. Walker believes the bugs shelter themselves when the sea is at all rough by keeping at a sufficient distance {553}below the surface; they can dive with facility, and are gregarious. They are frequently found close to the shore, and Mr. Walker has even met with them on land. The stink-glands of other Hemiptera are said by Nassonoff to be replaced in _Halobates_ by peculiar ventral glands. An allied genus, _Halobatodes_, was supposed to be oceanic, but this is not the case, some of the species having been found recently in fresh water in India, and others in estuaries at Port Darwin. A remarkable allied form, _Hermatobates haddoni_, was recently discovered by Professor Haddon in Torres Straits. Apart from the oceanic life, _Halobates_ is by no means the most extraordinary of the Hydrometridae. The Javanese _Ptilomera laticaudata_ repeats some of its peculiarities, and is of larger size, with the sexes very different. The most remarkable of the family is perhaps the fresh-water genus _Rheumatobates_ (Fig. 266), in which the males have peculiar prehensile antennae that look like legs. These curious Insects inhabit North America and the West Indies.

[Illustration: Fig. 266—_Rheumatobates bergrothi._ × 10. West Indies. (After Meinert.)]

We may here notice an enigmatic Insect called _Hemidiptera haeckeli_ by Léon. From the single specimen known it is concluded that the Insect has only one pair of wings, and that they are attached to the metathorax. It is, however, possible, as {554}suggested by Bergroth,[489] that the anterior pair have been detached by some accident.

FAM. 10. HENICOCEPHALIDAE.—_Head swollen behind the eyes so as to form a sort of globe, on the anterior part of which the ocelli are placed. Rostrum extremely short. Elytra rather large, of one consistence throughout; conspicuously veined._—There is only one genus; it is very widely distributed, about a dozen species being known; one of these occurs in the south of Europe. These curious little bugs appear to be most nearly allied to the Reduviidae. According to Westwood and others they are somewhat gregarious; a Tasmanian species dances in the air after the fashion of midges or May-flies, and dispenses an agreeable, musk-like odour.

[Illustration: Fig. 267—_Carcinocoris binghami_ (Phymatidae). Burma.]

FAM. 11. PHYMATIDAE.—_Front legs of peculiar structure, short and stout, with long coxae, short thick femora, and tibiae curvate, pointed; frequently without tarsi._—The Insects of this family are believed to be predaceous, the structure of the legs being such as is called raptorial, and one species, _Phymata erosa_, being known to capture and suck honey-bees in North America. There are only about seventy species of Phymatidae known. We have {555}none in Britain, though there are a few in Southern Europe; one of these, _P. crassipes_, extends as far north as Paris. The distinction of the family from Reduviidae is doubtful.[490] There are a few very rare forms (Fig. 267) in which the front tibia is articulated to the femur in such a way that a pair of pincers is formed: the tarsus is in this form, as well as in some other Phymatidae, absent.

[Illustration: Fig. 268—_Ghilianella filiventris._ Brazil. A, the female Insect. B, extremity of the body of the male.]

FAM. 12. REDUVIIDAE.—_Head more or less elongate, very movable, eyes placed much in front of the thorax, ocelli, when present, behind the eyes. Proboscis short, or moderately short, not extending on to the breast, in repose curved under the head so as to form a loop therewith. Elytra, when present, consisting of three divisions. Tarsi three-jointed._—This is one of the largest and most important families of Hemiptera. Upwards of 2000 species are already known; the habits seem to be chiefly of a predaceous nature, the creatures drawing their nutriment from the animal rather than from the vegetable kingdom, and their chief prey being in all probability other kinds of Insects. There is, perhaps, no family of Insects exhibiting a greater variety of form and colour. The Emesids are amongst the most delicate of Insects, equalling in this respect the {556}daddy-long-leg flies; they are, however, highly predaceous; their front legs are peculiarly formed for capturing and holding their prey, and have long coxae, like _Mantis_, so that these Insects are commonly mistaken for small or young Mantises, from which their sucking proboscis at once distinguishes them. This curious starved-looking form of bug reaches its maximum of peculiarity in the South American genus _Ghilianella_ (Fig. 268). According to Pascoe the linear form enables the young larva to be carried about by the mother, the long slender abdomen of the larva being curled around the thorax of the parent. _Ploiaria pallida_, from Woodlark Island, is an Insect of excessive fragility and elegance, with the long thin legs coloured with alternate patches of black on a white ground, giving rise to a very curious appearance remarkably analogous to what we find in some of the equally delicate daddy-long-leg flies.

[Illustration: Fig. 269—_Nabis lativentris_, young. Cambridge. A, Insect seen from above; B, profile.]

We have three species of Emesides in Britain, but most of our Reduviidae belong to the sub-family Nabides. These approximate to ordinary bugs in appearance and characters more than do any other of the Reduviidae. One of our indigenous Nabides is of great interest from the curious resemblance it has to an ant (Fig. 269). The likeness is brought about by the sides of the base of the abdomen being very pallid in colour, except a dark mark in the middle; this mark is in shape like the pedicel of an ant. Viewed in profile it is found that on the base of the abdomen there is an elevation like the "scale" in this position in {557}ants, and that the abdomen is extremely ant-like in form. This resemblance is quite parallel with that of an Orthopteron to an ant (see Vol. V. p. 323); the Insect is by no means uncommon, and it is strange that this curious case of resemblance should hitherto have escaped notice. The bug runs about on plants and flowers, and is frequently in company with ants, but we do not know whether it preys on them. Not the least remarkable of the facts connected with this Insect is that the resemblance is confined to the earlier instars; the adult bug not being like an ant. We may here mention that there are numerous bugs that closely resemble ants, and that on the whole there is reason to believe that the resembling forms are actually associated during life, though we really know very little as to this last point.

[Illustration: Fig. 270—_Ptilocnemus sidnicus._ Australia. (After Mayr.)]

[Illustration: Fig. 271—_Myiodocha tipulina._ China.]

The little sub-family Holoptilides, with twenty-five species, but widely distributed in the Eastern hemisphere, is remarkable on account of the feathered {558}antennae and legs of its members (Fig. 270). Altogether fourteen sub-families are recognised, the most extensive one being Harpactorides, including a great variety of remarkable forms; in the South American genus _Notocyrtus_ (better known as _Saccoderes_, Fig. 257), the prothorax is swollen and covers the body to a greater or less extent in the fashion of a hood. In _Yolinus_ and _Eulyes_ the coloration is the most conspicuous system that could be devised, the sides of the abdomen (connexivum) being expanded into bright-red lobes on which are placed patches of polished-black. The most remarkable form of Reduviid is, perhaps, one from China (Fig. 271) of considerable size, of great fragility, and greatly resembling, like some Emesides, a daddy-long-legs fly, though it does not belong to the Emesides. It is an altogether anomalous form. According to Seitz there is found on the Corcovado in Brazil a Reduviid that exactly resembles one of the dark stinging-wasps of the genus _Pepsis_, and the bug makes the same sort of movements as the wasp does, though these are of a kind quite different from those of ordinary bugs.[491]

[Illustration: Fig. 272—Eggs of _Endochus cingalensis_. "The eggs are attached to a leaf and to each other by a viscid substance; eggs red, the cover pale yellow, with the club white at the tip."—MS. note of E. E. Green.]

Although the attacks of Reduviidae on animals are usually confined to the smaller and more defenceless kinds, yet this is by no means invariably the case; there are in fact numerous species that do not hesitate to attack man himself. Several species of _Reduvius_ do this in Southern Europe, and are frequently met with in houses. _R. personatus_ is the only species of the genus in England; though far from common anywhere, it is sometimes found in houses, and is said to destroy the common bed-bug; it is able to pass its whole existence in our habitations, for the young are found as frequently as the adult, and are usually concealed by a quantity of dusty matter, or refuse, adhering to the body. This habit of covering the body with some foreign substance is natural to the Insect, the young that are found on trees being covered with matter derived therefrom. Darwin has given us an account of {559}the Benchucha,[492] a bug an inch long, which in South America attacks human beings after the fashion of the common bed-bug. In this case no ill-effects follow the attack, but in the case of _Conorhinus sanguisuga_ in Arizona, great pain and inflammation ensue and may end in the gathering and discharge of pus.

Not the least remarkable of characters of _Reduviidae_ is the form of the eggs of some of the species (Fig. 272, and Vol. V. Fig. 78, C); the egg bearing a peculiar operculum, the purpose of which is at present quite mysterious.

FAM. 13. AËPOPHILIDAE.—A single species forms this family. It is of considerable interest, as it is incapable of flight, passing a large part of its life covered by the sea. _Aëpophilus bonnairei is a small Insect with quite short head, without ocelli, and with the organs of flight represented by a pair of very short elytra, with rounded hind-margins._ It is found on the shores of Western France, and, as a great rarity, on our own south coast. It no doubt sucks small soft animals. In the Channel Islands it occurs in spots where it is nearly always covered by a considerable depth of water.

FAM. 14. CERATOCOMBIDAE.—_Minute bugs with ocelli and elytra. Rostrum free. Head not broad, somewhat prolonged in front; eyes close to the thorax. Elytra usually without a distinctly separated membrane. Tarsi three-jointed._—This family includes at present only a few, minute, fragile bugs, that have often been classified with Cimicidae or Anthocoridae. We have only two British species, one of which, _Dipsocoris alienus_, is common amongst the damp shingle at the margins of the burns and waters of Scotland.

FAM. 15. CIMICIDAE.—_Ocelli absent; elytra very short and broad, so that the broad abdomen is left uncovered. Head short and broad. Rostrum received in a groove beneath the head. Tarsi three-jointed._—Although this family consists of only a dozen species, it is the most notorious of all the Order, as it includes the detestable _Cimex lectularius_ or common Bed-bug. This Insect is now peculiar to the habitations of man, and is said not to trouble savage races; or rather it is supposed to be present only when the habitations have a certain degree of comfort and permanence. It has no fixed period of the year for its development, but the generations succeed one another so long as the temperature {560}is sufficiently elevated; during too cold weather the Insects merely become stupefied, their lives being as it were interrupted till warmth returns. It is a favourite food with other Insects, and is destroyed by cockroaches and ants as well as by _Reduvius_; the small black ant _Monomorium_ will, it is said, clear a house of the bed-bug in a few days. Nothing is really known as to the origin of this Insect; it is now very widely distributed. The other species of the family frequent birds and bats, and are very similar to the common bug. The genus to which the bed-bug belongs is in many works called _Acanthia_ instead of _Cimex_. Other authors apply the term _Acanthia_ to _Salda_, but it is better to allow the name _Acanthia_ to fall into disuse.

FAM. 16. ANTHOCORIDAE.—_Minute bugs, usually with ocelli and with elytra; the latter occasionally abbreviated, but usually fully developed, with membranous tip. Head prolonged in the middle in front much beyond the insertion of the antennae; eyes not far from the thorax. Rostrum free._—These small and obscure Insects appear to be rather numerous in species, and to be chiefly connected with woods and forests. Some of the species live in ants' nests. We have 27 British species belonging to 11 genera. About 200 species of the family are known. The members of the sub-family Microphysides are remarkable from the great dissimilarity of the sexes, for which it is not possible to assign any reason.

[Illustration: Fig. 273—_Polyctenes fumarius._ (After Westwood.)]

FAM. 17. POLYCTENIDAE.—_Proboscis-sheath three-jointed, tarsi four-jointed, antennae four-jointed. Tegmina quite short, of one consistence._—The four or five anomalous species forming this family are parasites on bats of the genus _Molossus_, and have been found in both the Eastern and Western hemispheres. Westwood, who first described {561}them,[493] treated them as aberrant Anoplura or Lice, but there do not appear to be any sufficient grounds for removing these parasites from Hemiptera-Heteroptera. The condition of their alar organs reminds one of what exists in _Cimex_ and _Aëpophilus_, and the mouth is not known to possess any very peculiar structure. We have had no opportunity of making a thorough examination of _Polyctenes_, and therefore speak with some diffidence.

[Illustration: Fig. 274—_Helopeltis_ sp. East India.]

[Illustration: Fig. 275—Section of a stem with egg of a Capsid bug allied to _Helopeltis_ (Moesa-blight). × 58. (After Dudgeon.)]

FAM. 18. CAPSIDAE.—_Moderate-sized or small bugs, of delicate consistence, without ocelli; the elytra and wings usually large in proportion to the body, the former with two cells (occasionally only one) in the membrane. Antennae four-jointed, the second joint usually very long, the terminal two more slender than the others. The proboscis not received in a groove. Scutellum exposed, moderately large. Tarsi three-jointed. Female with an ovipositor capable of exsertion._—This family is one of the most extensive of the Hemiptera; we have about 170 species in Britain, where they are most abundant in the south. The exotic species have been but little collected. Their colours are usually delicate rather than vivid, and are never metallic. They frequent plants of all kinds, and many of them skip by the aid of their wings with great agility in the sunshine. The majority probably suck the juices of the plants, but some are known to prey on other Insects. The species of the Indian genus _Helopeltis_ (Fig. 274) are remarkable by possessing a knobbed spine projecting straight up from the scutellum, making the individual look as if it were a specimen with a pin through {562}it: they attack the tea-plant and do considerable damage. They are known as Mosquito-blight. The egg is of comparatively large size, and is placed by the bug in the stems of the tea-plant, but attached to one end of the egg are two long slender threads that project externally. A similar egg (Fig. 275) and method of oviposition have been described by Mr. Dudgeon as occurring in another species of Capsidae, called Moesa-blight, in India.[494]

FAM. 19. SALDIDAE.—_Head short and broad, with large, prominent eyes. Ocelli present. Proboscis not applied to under surface of head or breast in repose. Scutellum large, not covered. Elytra covering the upper surface of the abdomen, formed of three distinct parts. Tarsi three-jointed._—These little bugs run with velocity over mud in damp places, or live in wet moss; some of them can jump; they are all of dark or obscure colour. There are only three genera: _Salda_, of which we have numerous British species, being the principal one.

SERIES 2. CRYPTOCERATA.

The remaining families of Heteroptera are of aquatic habits, and form in nearly all works a separate division called Hemiptera Cryptocerata (or Hydrocorisae, or Hydrocores), distinguished by the antennae being apparently absent; they are, however, really present, being situate on the under side of the head, to which they are closely pressed, or in some cases placed in a pocket in front of each eye. There are six of these families. Schiödte is doubtless correct in treating this division as an unnatural one; it is, however, generally adopted, and is convenient for the purposes of nomenclature and arrangement.

FAM. 20. GALGULIDAE or PELOGONIDAE.—_Form short and broad; head very broad, with prominent eyes, ocelli present. Hind legs thin, formed for running._—The Insects of this family are but little known; they are only sub-aquatic in habits, frequenting damp places at the margins of streams and waters. The presence of ocelli distinguishes them from other water-bugs, with which indeed the Galgulidae appear to be but little related. There are only about twenty species of the family known. We possess none in Britain; but one, _Pelogonus marginatus_, occurs {563}in South Europe. The other members of the family are very widely scattered over the surface of the earth.

FAM. 21. NEPIDAE.—_Abdomen furnished behind with a long slender siphon; front legs more or less elongate for capturing prey, placed quite at the front edge of the prothorax._—This family consists of two interesting but very dissimilar genera, _Nepa_ and _Ranatra_. Both are widely distributed over the earth, and are rather numerous in species.[495] We have one species of each genus in Britain. _Nepa cinerea_, the common "water-scorpion," is one of the commonest of Insects in Southern Britain, living concealed in shallow waters when nearly or quite stagnant. _Ranatra linearis_ (Fig. 276) is much less common, and appears to be getting rarer; it is not recorded from farther north than Cambridge.

[Illustration: Fig. 276.—_Ranatra linearis_, with the two portions, _a_, of the respiratory siphon separated. Cambridge.]

The nature of the respiratory arrangements in these Insects is of considerable interest; the long tube at the extremity of the body consists of two parts (as shown in Fig. 276) brought together in the middle, one from each side. Lacaze-Duthiers states that the processes are elongated pleurae, but in the young it is far from clear that this is the case. However that may be, they seem to convey air to the true breathing organs, situate inside the cleft on the apical part of the abdomen itself; but details as to the way in which transfer of air is effected along this {564}very protracted passage are not forthcoming. The development in _Nepa_ has been studied to a certain extent. The apical stigmata are the only pair of the abdominal stigmata that exist in the imago of _Nepa_, the other six pairs being obliterated; the third, fourth, and fifth, according to Schiödte, in a very peculiar manner: hence, as Martin says,[496] the respiratory system is metapneustic. In an earlier stage of the life, however, these six pairs of stigmata exist in functional activity placed in a groove on the under surface of the body; so that the condition is that termed peripneustic, and remains so till the final moult, when the long siphon appears. In the early life there is a short prolongation from the end of the body in connection with the pair of grooves alluded to, but it is a single unpaired organ, and does little therefore to explain the appearance of the siphon, which must, at present, be considered as being suddenly developed at the last moult.

[Illustration: Fig. 277—Egg of _Nepa cinerea_. (After Korschelt.)]

The eggs of Nepidae are remarkable objects; that of the common water-scorpion bears seven filaments at one end (Fig. 277); while that of _Ranatra_ is more elongate, and bears only two, very elongate, threads. These eggs are deposited in the stems of water-plants, being introduced therein, so that the body of the egg is concealed while the threads project: those of _Ranatra_ are placed in stems floating on the water, and in consequence of the threads the stems look as if they were infested by some fungus. The structure and formation of the eggs have been investigated with considerable detail by Korschelt.[497] He looks on the filaments as pneumatic, and considers that they supply a coating of air to the body of the egg; they consist of a spongy mass encircled by two layers of egg-shell, both of these latter being peculiar in structure; the spongy mass is continuous with a layer of the same kind of substance placed on the interior of the shell of the body {565}of the egg. It will be recollected that we have described (p. 562) an egg, apparently of the same nature, deposited by Capsids in the stems of land plants, so that it is very doubtful whether the threads are really connected with the aquatic development of the embryo in Nepidae. But the most interesting feature connected with these eggs is, according to Korschelt, the mode of development of the filaments, which is _sui generis_; the shell of the egg is developed in the ordinary manner as an exudation or excretion from epithelial cells; but the shell of the filament is formed as an intracellular product; a mode of chitin-formation that appears to be peculiar to this structure. Korschelt remarks that "it is in the highest degree worthy of attention how by any process of development through a large number of successive generations so complex a condition could be established as the result of adaptation to external conditions; and this becomes even more interesting when we remember that highly peculiar special processes and departures from the usual modes of tissue-formation are necessary to permit the development of this apparatus."[498]

FAM. 22. NAUCORIDAE.—_No ocelli, and no terminal process to the body; front legs inserted on or near the front of the prosternum. Anterior femora usually broad and flat._—The members of this family are truly aquatic, and swim readily in the water. The family is small, including about nine genera and thirty species, but, like many water-Insects, the genera are widely distributed. We have two in Britain—one of them, _Naucoris_, common; the other, _Aphelocheirus_, rare.

FAM. 23. BELOSTOMIDAE.—_No ocelli, and no long terminal tube to the body; front legs inserted near the front of the prosternum. Posterior tibiae not spiny; flattened and provided with swimming hairs._—Although these Insects have been classified with Nepidae they have but little relation therewith; on the other hand, the distinctions from Naucoridae are far less important. The family includes some of the largest Insects. The South American _Belostoma grande_ attains a length of four or four and a half inches. Notwithstanding their considerable size Belostomidae exist in very large numbers in some localities, and frequently destroy young fish by aid of the powerful though short rostrum.

{566}[Illustration: Fig. 278—_Zaitha anura_, carrying eggs on its back. West Indies.]

[Illustration: Fig. 279—Antenna of _Belostoma_ sp. A, One side of the under surface of the head, with antenna, _b_, extended; B, with the antenna retracted, _a_, Side of head; _c_, pocket for antenna; _d_, position of the eyes. The corresponding joints of the antenna are numbered 1, 2, 3, 4 in each figure.]

They appear to be unable to resist the attraction of artificial light, and are consequently sometimes destroyed in large numbers. It has long been known that species of the genera _Diplonychus_ and _Zaitha_ carry their eggs on their backs. There is no special receptacle for the purpose, but the eggs are kept in their peculiar position by means of a cement insoluble in water. It has been stated by Dimmock that they are placed in position by means of a long, flexible ovipositor. Schmidt, however, found that a specimen of _Diplonychus_, bearing eggs and examined by him, was a male, and he subsequently found that this was the case with other egg-bearing individuals of other species, so that the mode in which the eggs are placed in this position and the object of so curious a habit, remain uncertain. The species of _Belostoma_ are highly remarkable on account of the curious and complex structure of their antennae, in respect of which the nearest analogy is to be found in the large Coleoptera of the genus _Hydrophilus_. A very deep, ear-like pocket, exactly suited to the form of the antennae, exists on the under side of the head; hence in repose no sign of the peculiar shape of the antennae exists. When the antennae are placed in this ear-like pocket only the one side of the basal joints is exposed, the long processes being received into the deep pocket. In _Hydrophilus_ the antenna is used as an accessory organ of respiration, and it will be interesting to learn whether this is also the case in _Belostoma_. Belostomidae have patches of air-carrying pubescence, analogous with those of _Hydrophilus_, on the under sides of the body, elytra and wings, but we do not {567}know how they are charged. Another extremely interesting analogy is found in the manner in which the elytra are locked to the body; a projection from the thoracic side-pieces, forming a long pouch, into which a fold on the inner side of the elytra fits, the two being subsequently locked by the action of some special projections. This arrangement is similar to that which exists in the anomalous family of water-beetles Pelobiidae. In order to make this mechanism more perfect the side-pieces in _Belostoma_ form free processes. Martin has informed us that the young have the metasternal episternum prolonged to form a lamella that he thinks may be for respiratory purposes.[499] About twelve genera and upwards of fifty species of Belostomidae are known. None exist in our isles, but several species extend their range to Southern Europe. In the waters of the warm regions of the continents of both the Old and New Worlds they are common Insects, but as yet they have not been found in Australia.

FAM. 24. NOTONECTIDAE.—_Prosternum short, so that the legs are placed near the back part of it as well as near the front; back of the head overlapped by the front of the pronotum._—The water-boatmen are extremely common in our ponds, where they may be seen rising to the surface and raising the posterior extremity of the body for breathing. They swim on their backs instead of in the usual position, and have an elaborate arrangement of long hairs on the body to assist them to carry about an air-supply. They are said to be lighter than the water, and to have some difficulty in keeping away from the surface. _Notonecta glauca_ is the only British species, but we have a second minute Insect, _Plea minutissima_, belonging to the family. It lies in the mud at the bottom of shallow waters, and may sometimes be fished up in great numbers. It is considered by some authors to form a distinct family. The oviposition of _Notonecta_ has been observed by Regimbart; the eggs are inserted into the stems of aquatic plants.

FAM. 25. CORIXIDAE.—_Prosternum short, as in Notonectidae; summit of the head free from the thorax._—We have numerous species of the genus Corixa in Britain; and others extremely similar in appearance occur in various parts of the world. The head is remarkably free, and capable of great rotation. On dissection it is found to be attached to the thorax only by a {568}narrow area; in this respect it differs widely from _Notonecta_, which possesses an extremely large occipital foramen, and the head of which possesses but little freedom of movement. The extremely short proboscis is more or less retractile, and therefore frequently appears absent. A second British genus consists of a single species, _Sigara minutissima_. These Insects, unlike _Notonecta_, are quite at home beneath the water, where they scurry about with extreme rapidity, and occur sometimes in enormous numbers. In Mexico the eggs of _Corixa americana_ and of _C. femorata_ are used as food, and are said to be very nice. The Insects themselves are used as food in both Mexico and Egypt. The species of this family can make a noise beneath the water by rubbing the front feet against the proboscis.[500] The males have a very complex asymmetry of the terminal segments, and in some species possess on one side of the dorsal surface a curious asymmetrical organ consisting of rows of very closely-packed, intensely black, comb-like plates, called by Buchanan White a strigil. This organ seems to be similar to the peculiar structures found on the terminal segments of certain species of Scutellerides.

Sub-Order II. HOMOPTERA.[501]

FAM. 1. CICADIDAE.—_Head with three ocelli, placed triangularly on the summit between the compound eyes; antennae consisting of a short basal joint, surmounted by a hair-like process divided into about five segments. Front femora more or less thick, armed with teeth. Peduncle (or basal joints) of antennae without sensitive organs._—This important family consists chiefly of large Insects, few being as small as one inch across the expanded wings, while in some the expanse is as much as seven inches. As a rule the four wings are transparent and shining, with the nervures remarkably distinct and dark coloured; but there are numerous forms where the whole creature, including the wings, is highly pigmented in a showy manner; frequently in black and yellow. Cicadas are said to be without any special protection, and to be destroyed in considerable numbers by birds and other animals. The body is broad and robust, and is never shaped into the extravagant forms we meet with in some of the other families of Homoptera.

{569}[Illustration: Fig. 280—_Cicada septendecim._ North America. (After Riley.) A, Larva; B, nymph; C, nymph skin after emergence of the imago, D; E, section of twig with series of eggs; F, two eggs magnified.]

Cicadidae are almost confined to the warmer regions of the earth, but we have one species, a great rarity, in the extreme south of England; altogether there are about 800 species known. These Insects are seen above ground—so far as the life-histories are at present known—only in the perfect condition, the creatures in their earlier stages being subterranean and living on roots. As soon as the individual comes out of the ground it splits open the nymph-skin, and the perfect Cicada emerges. One species—the North American _Cicada septendecim_—is a most notorious Insect owing to its life-cycle of seventeen years. It is considered that the individual, after nearly seventeen years of underground existence, comes to the surface and lives for a brief period the life of a noisy Insect. This is the only Insect at present known having so considerable a longevity. This fact, and several other peculiarities, have attracted much attention, so that there is an extensive literature connected with the seventeen-year Cicada. It has a wide distribution over the United States, but does not confine its appearance to every seventeenth year, being found somewhere or other—frequently in numerous localities—almost every year. The evidence as to its periodicity has been obtained by taking the locality and other points into consideration as well as the year of appearance. {570}By so doing it has been found possible to establish the existence of twenty-two broods which are distinguished by consecutive numeration. This being done, the evidence as to the years during which Cicadas have appeared in any given locality is examined, and the result is believed to bear out the view that the life-cycle of the individual Insect is really one of seventeen years. According to this view there are, underground, in certain localities individuals of different ages that will appear on the surface as mature individuals in different years. Thus in 1885 it was understood that there were underground in Alabama two broods, viz. brood xviii. that would appear on the surface in 1894, and brood iv. that would appear on the surface in 1896. The predictions made as to the years in which Cicadas would appear in some given locality are considered to have proved correct. Moreover,

## particular entomologists have in certain localities verified by personal

examination the appearance of the Insects for several consecutive periods of seventeen years. These facts appear fairly conclusive, but they are much complicated by another point, viz. that in certain localities the period is one of thirteen, not of seventeen, years. This is to some extent a question of climate, the thirteen-year interval being chiefly characteristic of the Southern States. It is not, however, entirely so, for there are localities in which the broods have an interval of either thirteen years or seventeen years. Another fact should be remembered, viz. that it is admitted that not quite all the individuals of a particular brood are true to their proper time of appearance; in other words, a few specimens may appear precociously a year or two before their comrades, while some may lag behind to a considerable extent. It is therefore a matter for great surprise that, under these circumstances, the broods should keep distinct at all, for one would suppose that time-variation of this kind would lead to completely obscuring the distinctness of the broods. We must also call attention to the fact that both the seventeen-year and the thirteen-year broods have a dimorphic form, or sub-species, called _C. cassinii_ which accompanies the ordinary form, with which it is apparently as a rule not connected by intermediates.[502]

{571}Cicadidae are provided with powerful ovipositors. The eggs of _C. septendecim_ are deposited in the woody stems of bushes; after remaining there a few weeks the young hatch out, drop to the ground, and, as previously stated, disappear for nearly seventeen years, nearly the whole of which time is passed in the larval state, the nymph-condition existing for only a few days. They feed on the roots of various trees; it has been said that they are injurious in this way, but other authorities maintain that they suck only a moist exudation from the roots. It is very difficult to obtain information as to their strange, prolonged, subterranean life; it said that the Insects sometimes penetrate to a great depth—ten feet, even twenty feet are mentioned;—and as great changes may take place on the surface during their long lives, these Insect Rip Van Winkles sometimes emerge in very strange conditions, and may appear even in deep cellars. When the pupa comes to the surface it hooks itself on to the stem of some plant or other object, the skin of the back splits, and the Cicada emerges. Among the inexplicable peculiarities of this Insect must be mentioned the fact that when emerging it sometimes constructs chimneys, or flues, extending several inches above the surface of the ground. The reason for this is much disputed; it was said that they are for refuge against inundations, but this appears to be very doubtful. Certain of the broods consist of an almost incalculable number of individuals, and it is very strange to hear woods, or other localities, that have been for many years free from these Insects, all at once resounding with their noisy song. The seventeen-year Cicada is considered to be doomed to a speedy extinction; the extension of cultivation and building, and the introduction to America of the English sparrow, are likely to prove too much for the Insect.

Although Hemiptera are classified by many among the Ametabola or Insects without metamorphosis, it is impossible to deny that the Cicadidae exhibit a considerable amount of metamorphosis, and they are usually mentioned as exceptional. The young (Fig. 280, A) is totally unlike the adult in form and colour, and maintains, to a certain extent, its existence by the aid of a different set of implements. The larva of the Cicada is colourless, with an integument of very feeble consistence, rather large antennae, and a remarkable pair of fossorial legs; {572}the wings are totally wanting. The mode of passage from the larval to the pupal state has not been recorded. The pupa, or nymph, differs from the larva by its much shorter, compressed form; by being encased in a remarkably hard shell; and by the antennae approximating in form to those of the adult. It has short wing-pads at the sides of the body; the front legs are remarkably powerful, and the creature is capable of moving about; the imago escapes from the pupa by the splitting dorsally of the middle of the thoracic segments. The empty pupa-skin does not shrivel, but retains its form, and in countries where Cicadas occur, frequently attracts attention by the strange form it presents, being often placed in a conspicuous position.

SONG.—Cicadas are the most noisy of the Insect world; the shrilling of grasshoppers and even of crickets being insignificant in comparison with the voice of Cicada. Darwin heard them in South America when the _Beagle_ was anchored a quarter of a mile from the shore; and _Tympanoterpes gigas_, from the same region, is said to make a noise equal to the whistle of a locomotive.[503] A curious difference of opinion prevails as to whether their song is agreeable or not; in some countries they are kept in cages, while in others they are considered a nuisance. The Greeks are said to have decided in favour of their performances, the Latins against them. Only the males sing, the females being completely dumb; this has given rise to a saying by a Greek poet (so often repeated that it bids fair to become immortal) "Happy the Cicadas' lives, for they all have voiceless wives."[504] The writer considers the songs of the European species he has heard far from unpleasant, but he is an entomologist, and therefore favourably prepossessed; and he admits that Riley's description of the performances of the seventeen-year Cicada is far from a satisfactory testimonial to the good taste of that Insect; Riley says, "The general noise, on approaching the infested woods, is a combination of that of a distant threshing-machine and a distant frog-pond. That which they make when disturbed, mimics a nest of young snakes or young birds under similar circumstances—a sort of scream. They can also produce {573}a chirp somewhat like that of a cricket and a very loud, shrill screech prolonged for fifteen or twenty seconds, and gradually increasing in force and then decreasing." The object, or use of the noise is very doubtful; it is said that it attracts the females to the males. "De gustibus non est disputandum!" perhaps, however, there may be some tender notes that we fail to perceive; and it may be that the absence of any definite organs of hearing reduces the result of a steam-engine whistle to the equivalent of an agreeable whisper. No special auditory organs have been detected[505] as we have already intimated; and certain naturalists, amongst whom we may mention Giard, think that the Insects do not hear in our sense of the word, but feel rhythmical vibrations; it is also recorded that though very shy the Insects may be induced to approach any one who will stand still and clap his hands—in good measure—within the range of their sensibilities. There is a good deal of support to the idea that the males sing in rivalry.

VOCAL STRUCTURES.—Although we may not be able to pronounce a final opinion as to the value to the Insect of the sounds, yet we cannot withhold our admiration from the structures from which they proceed. These are indeed so complex that they must be ranked as amongst the most remarkable voice-organs in the animal kingdom. They are totally different from the stridulating organs that are found in many other Insects, and are indeed quite peculiar to the Cicadidae. Some difference of opinion has existed as to the manner in which the structures act, but the account given by Carlet, some of whose figures we reproduce, will, we believe, be found to be essentially correct. The structures are partly thoracic and partly abdominal. On examining a male _Cicada_ there will be seen on the under surface two plates—the opercula—usually meeting in the middle line of the body and overlapping the base of the abdomen to a greater or less extent according to the species, sometimes nearly covering this part of the body; these are enlargements of the metathoracic epimera; they can be slightly moved away from the abdomen, and, as the latter part is capable of a still greater extent of movement, a wide fissure may be produced, displaying the complex {574}structures. In order to see the parts it is better to cut away an operculum; underneath it three membranes can be seen, an external, the timbal; an anterior, the folded or soft membrane; and a posterior, the mirror. This last is a most beautiful object, tensely stretched and pellucid, yet reflecting light so as to be of varied colours; there are also three stigmata, and some chambers connected with the apparatus. The sound is primarily produced by the vibrations of the timbal, to which a muscle is attached; the other membranes are probably also thrown into a condition of vibration, and the whole skeleton of the Insect helps to increase or modify the sound, which is probably also influenced by the position of the opercula. The stigmata probably play an important part by regulating the tension of the air in the chambers. In the female some of the structures are present in a rudimentary form, but there are no muscles, and this sex appears to be really quite voiceless.

[Illustration: Fig. 281.—Musical apparatus of _Cicada plebeia_. (After Carlet.) A, Ventral view (Operculum on right side is removed); _ap_, apophysis; C, cavern; _c_, trochantin (cheville of Réaumur); _ent_, part of internal skeleton of abdomen; _mi_, specular membrane; _m.pl_, soft or folded membrane; P, base of leg; _st_, _st′_, _st″_, stigmata; _t_, drum "timbale"; _v_, operculum; _1a_, first, _2a_, second abdominal segment: B, same seen laterally, portion of abdominal wall as well as operculum removed; A, point of insertion of hind wing; _Mes_, mesothorax; _sc_, scutum of metathorax; _3a_, third abdominal segment; rest as in A.]

FAM. 2. FULGORIDAE.—_Ocelli two (rarely three, or entirely obsolete), placed beneath the eyes or near the eyes, usually in cavities of the cheeks, antennae placed beneath the eyes, very variable in form; usually of two joints terminated by a very fine hair, the second joint with a peculiar texture of the surface, owing to the existence of sensitive structures_ (Hansen). _Form of head very diverse; vertex and face forming either a continuous curve, or the planes of the vertex and face forming an acute angle, or both {575}prolonged so as to form a projection or growth that may be monstrous. Prothorax neither armed nor unusually developed._

[Illustration: Fig. 282—_Fulgora candelaria._ × 1. China.]

This family is of large extent, and includes at present so great a variety of forms that it is really almost impossible to frame a definition that will apply to all. The unusual situation of the ocelli and the peculiar second joint of the antennae must at present be taken as the best diagnostic characters: occasionally a third ocellus is present. Some of the Fulgoridae are amongst the largest Insects, others are quite small. The family includes the so-called Lantern-flies, in which the front of the head forms a huge misshapen proboscis that was formerly believed to be luminous. Many of the species are of brilliant or beautiful coloration. A great many—and of very different kinds—have the curious power of excreting large quantities of a white, flocculent wax. This is exhibited by our little British Insects of the genus _Cixius_, and in some of the exotic forms is carried to an extent that becomes a biological puzzle. The Tropical American genus _Phenax_ may be cited as an example; being about an inch long it flies about with a large mass of this waxy substance twice as long as itself; indeed, in the Mexican _P. auricoma_, the waxy processes are four or five inches long. This wax forms a favourite food of certain kinds of Lepidoptera, and two or three larvae of a maggot-like nature may frequently be found concealed in the wax of the live Fulgorids; this has been recorded by Westwood as occurring in India; and Champion has observed it in the New World.[506] {576}The wax of Fulgorids is used by the Chinese for candles and other purposes; and this white Insect-wax is said to be much esteemed in India. Very curious chemical substances have been obtained from it, but its importance in the economy of the Insects that produce it is quite obscure. We have about seventy species of Fulgoridae in Britain. They belong to the subfamilies Tettigometrides, Issides, Cixiides, and Delphacides, which by many authors are treated as separate families. The exotic subfamily Flatides is highly peculiar. In some of its members the head is very different from that of the ordinary forms, being narrow, and the vertex and front forming a continuous curve. Some of these Insects are remarkably like butterflies or moths (_e.g._ the African _Ityraea nigrocincta_ and the species of the genus _Pochazia_), but the young are totally unlike the old, the posterior part of the body bearing a large bush of curled, waxy projections, several times the size of the rest of the body.

[Illustration: Fig. 283—A, B, _Heteronotus trinodosus_. A, Male seen from above; B, profile of female; _a_, terminal part of pronotum; _b_, terminal part of abdomen: C, front view of head and pronotum of _Cyphonia clavata_. Both species from Central America. (From _Biol. Centr. Amer. Rhynch. Homopt._ II.)]

FAM. 3. MEMBRACIDAE.—_Prothorax prolonged backwards into a hood or processes of diverse forms; antennae inserted in front of the eyes; ocelli two, placed between the two eyes._—This family is of large extent but its members are chiefly tropical, and are specially abundant in America. Although not of large size the Membracidae are unsurpassed for the variety and grotesqueness of their shapes, due to the unusual development of the pronotum. We figure two of these forms (Fig. 283).[507] Very little is known about their {577}habits and life-histories. We have only two species of the family in Britain, and these do not afford any ground for supposing that there are any peculiarities in their lives at all commensurate with the oddness of the Insect's structures. Belt has recorded the fact that in Nicaragua the larvae of certain Homoptera were assiduously attended by ants for the sake of a sweet juice excreted by the bugs, but it is by no means clear that these larvae were really those of Membracidae. In North America _Ceresa bubalus_ and _C. taurina_ place their eggs in an extremely neat manner in the woody twigs of trees. The young have but little resemblance to the adults, the great thoracic hood being absent, while on the back there is on each segment a pair of long, sub-erect processes having fringed, or minutely spiny, margins.[508]

FAM. 4. CERCOPIDAE.—_Ocelli two (occasionally absent) placed on the vertex; antennae placed between the eyes. Thorax not peculiarly formed._—In the characteristic forms of this family the front of the vertex bears a suture, touched on each side by one at right angles to it, or converging to it so as to form a triangle or a sort of embrasure; the hind tibiae have only one to three strong spines. The Cercopidae are much less extraordinary than many of the previously considered families. But some of them have the habit of secreting a large quantity of fluid; and when in the immature stages, certain of them have the art of emitting the liquid in the form of bubbles which accumulate round the Insect and conceal it. These accumulations of fluid are called cuckoo-spits or frog-spits; and the perfect Insects are known as frog-hoppers, their power of leaping being very great. The most abundant of the frog-hoppers in our gardens is _Philaenus spumarius_, a little Insect of about a quarter of an inch long, obscurely coloured, with more or less definite pale spots; it is so variable in colour that it has received scores of names. Some of the Insects do not use their fluid in this manner, but eject it in the form of drops, and sometimes cast them to a considerable distance. The phenomena known as weeping-trees are due to Cercopidae; some of the species make such copious exudations of this kind that the drops have been compared to a shower of rain. In Madagascar it is said that _Ptyelus goudoti_ exudes so much fluid that five or six dozen larvae would about fill a {578}quart vessel in an hour and a half. The frog-spit is considered by some naturalists to be a protective device; the larvae are, however, a favourite food with certain Hymenoptera, which pick out the larvae from the spits and carry them off to be used as stores of provision for their larvae. In Ceylon the larva of _Machaerota guttigera_ constructs tubes fixed to the twigs of the tulip-tree, and from the tube water is exuded drop by drop. According to Westwood, this Insect is intermediate between Cercopidae and Membracidae.[509]

FAM. 5. JASSIDAE.—_Ocelli two, placed just on the front margin of the head (almost in a line with the front of the eyes or more to the front) or on the deflexed frons. Hind tibiae usually with many spines._ This vaguely limited family includes a very large number of small or minute Insects, usually of narrow, parallel form, and frequently excessively delicate and fragile. They are often mentioned under the name of Cicadellinae. Ashmead distinguishes two families, Bythoscopidae, in which the ocelli are clearly on the frons or front, and Jassidae, in which they are on the upper edge thereof. _Ulopa_, _Ledra_, and a few other exceptional forms, are also by many distinguished as representatives of distinct families. Very little is actually known as to the life-histories of these small and fragile Insects, but it is believed that the eggs are usually deposited in the leaves or stems of plants, and more particularly of grasses. In North America the development of _Deltocephalus inimicus_, from hatching to assumption of the adult form, has been observed by Webster to occupy about six weeks. As Jassidae are numerous both in species and individuals it is believed that they consume a considerable part of the vegetation of pastures. Osborn has calculated that on an acre of pasture there exist, as a rule, about one million of these hoppers, and he considers they obtain quite as large a share of the food as the Vertebrates feeding with them.

FAM. 6. PSYLLIDAE.—_Minute Insects with wings usually transparent, placed in a roof-like manner over the body; with three ocelli, and rather long, thin antennae of eight to ten joints. Tarsi two-jointed._—These small Insects have been studied chiefly in Europe and North America, very little information having yet been obtained as to the exotic forms. They are about the {579}size of Aphidae, but in form and general appearance remind one rather of Cicadidae. The wings are in many cases even more perfectly transparent than they are in many Cicadidae. They are sometimes called springing plant-lice, as their habit of jumping distinguishes them from the Aphidae. Löw has called attention to the remarkable variation in colour they present in conformity with either the age of the individual, the food-plant, the climate, and, more particularly, the season of the year.[510] Réaumur long since pointed out that at their ecdyses these Insects go through a remarkable series of changes of colour, and Löw found that this did not take place in the normal manner in the winter generation that hibernates. This has been confirmed by Slingerland in North America in the case of _Psylla pyricola_,[511] which has been introduced there. He finds that there are several generations in the year, and that the hibernating adults differ from the summer adults in size, being nearly one-third larger; in their much darker colouring; and especially in the coloration of the front wings.

[Illustration: Fig. 284—_Psylla succincta._ x 15. Europe. (After Heeger.) A, larva before first moult. B, larva after third moult. C, adult.]

In the earlier stages, Psyllidae differ greatly in appearance from the adult forms; the legs and antennae in the newly hatched larvae are short, and have a less number of joints. In the nymph the shape is very peculiar, the large wing-pads standing out horizontally {580}from the sides of the body, so that the width of the creature is about as great as the length. The period occupied by the development apparently varies according to season. Witlaczil, who has given an account of many details of the anatomy and histology of various Psyllidae,[512] considers that there are four larval stages; Heeger's account of _Psylla succincta_ is not quite clear on this point, and Slingerland indicates a stage more than this, the perfect Insect being disclosed as the result of a fifth moult; it is probable that he is correct. In these earlier stages the body bears long hairs called wax-hairs; according to Witlaczil in the young larvae of certain species—_Trioza rhamni_, e.g.—these are broad and flat, so as to make the body appear studded with oval processes; he states that these hairs change their form during the growth of the individual. Nothing is more remarkable in Psyllidae than the amount of matter they secrete or exude from their bodies; in some species the substance is a "honey-dew," and the nymph may keep itself covered with a drop of it: in other cases it is solid, as shown in Réaumur's figures of _P. buxi_, where this exudation forms a string several times longer than the body, and attached to it. Another form of exudation is a light downy or waxy matter. Slingerland says that honey-dew was exuded by _P. pyricola_ in such quantities that it "literally rained from the trees upon the vegetation beneath; in cultivating the orchard the back of the horse and the harness often became covered with the sticky substance dropping from the trees. It attracts thousands of ants, bees, and wasps, which feed upon it." The writer last year observed in the New Forest a stunted sloe-bush, about which a large number of Bombi were busily occupied; and examination showed that they were thrusting their proboscides into the curled and deformed leaves, in which were secreted nymphs of a _Psylla_ exuding honey-dew. It must not be assumed that this honey-dew is the excrement of the Insect; this also is known, and is a different substance. Those who have tasted it say that the honey-dew has a clean, good flavour. The source of the honey-dew is not quite certain, but it seems probable that it comes, like the solid matter figured by Réaumur, directly from the alimentary canal, and not from hairs or pores on the body. Psyllidae give rise to definite formations or galls on certain plants; sometimes these Psyllid galls are mere changes in form of a limited part, or {581}parts, of a leaf, giving rise either to crumpling or to growth of a portion in one direction only, so that on one surface of the leaf a swelling is formed, and on the opposite side a more or less deep cavity in which the Insect dwells. A formation of this kind on the leaves of _Aegopodium podagraria_ is described by Thomas[513] who states that the growth is due to the deposition of an egg of the _Psylla_, and is independent of the after life of the Insect; a fungus—_Puccinia aegopodii_—forms similar structures on the leaves. Structures much more definite than this may be the result of the attacks of Psyllidae; for an example the reader may refer to Réaumur's account of _Psylla buxi_.[514] In Australia and Tasmania there are Psyllidae known as Laap or Lerp Insects, the products of which are called leaf-manna or Lerp, and are used as food. This manna is a scale produced by the young Insect on the leaves of _Eucalyptus_ as a covering or protection. The scale is fastened to the leaf by a hinge, and is somewhat like the shell of a cockle. Although the scales are said to be in some cases objects of great beauty, very little is known about these Australian Psyllidae, one of which has, however, been referred by Schwarz to the genus _Spondyliaspis_, Signoret.[515] About 160 species of Psyllidae are known to occur in the Palaearctic region, and about fifty of them have been found in Britain.[516]

FAM. 7. APHIDAE (_Plant-lice or Green-fly._)—_Minute Insects; as usually met with destitute of wings, though many individuals have two pairs of transparent wings. Antennae long, or moderately long, three- to seven-jointed; abdomen frequently with a pair of tubes (siphons), or short processes on the upper side of the fifth abdominal segment. Tarsi two-jointed, first joint sometimes excessively short._—These soft-skinned Insects are frequently called blight, and are so abundant in temperate climates that a garden, however small, is sure to afford abundance of specimens during the warm months of the year. This great abundance is due to peculiarities in the physiological processes that render these obscure little animals highly important creatures; the individual life for several generations is restricted to constant, or at any rate copious, imbibition of food, accompanied by an almost uninterrupted {582}production of young by parthenogenetic females, the young so produced becoming rapidly (sometimes in the course of eight or ten days, but more usually in about twenty days) themselves devoted to a similar process; so that in the comparatively short period of a few months the progeny resulting from a single individual is almost innumerable. This remarkable state of affairs is accompanied by other peculiarities of physiology, with the result that the life-histories of successive generations become very diverse, and complex cycles of series of generations differing more or less from one another are passed through, the species finally returning to bi-sexual reproduction, and thus inaugurating another cycle of generations. The surprising nature of these facts has in the last 150 years caused an immense amount of discussion, but no satisfactory light has yet been thrown on the conditions that really give rise to the exceptional phenomena. These phenomena are (1) parthenogenesis; (2) oviparous and viviparous reproduction; (3) the production of generations of individuals in which the sexes are very unequally represented, males being frequently entirely absent; (4) the production of individuals differing as to the acquirement of wings, some remaining entirely apterous, while others go on to the winged form; (5) the production of individuals of the same sex with different sexual organs, and distinctions in the very early (but not the earliest) stages of the formation of the individual; (6) differences in the life-habits of successive generations; (7) differences in the habits of individuals of one generation, giving rise to the phenomenon of parallel series. All these phenomena may occur in the case of a single species, though in a very variable extent.

The simple form of Aphid life may be described as follows:—eggs are laid in the autumn, and hatch in the spring, giving rise to females of an imperfect character having no wings; these produce living young parthenogenetically, and this process may be repeated for a few or for many generations, and there may be in these generations a greater or less number of winged individuals, and perhaps a few males.[517] After a time when temperature falls, {583}or when the supply of food is less in quantity, or after a period of deliberate abstention from food, sexual individuals are produced and fertilised eggs are laid which hatch in the spring, and the phenomena are repeated. In other cases these phenomena are added to or rendered more complicated by the intercalated parthenogenetic generations exhibiting well-marked metamorphosis, of kinds such as occur in apterous or in winged Insects; while again the habits of successive generations may differ greatly, the individuals of some generations dwelling in galls, while those of other generations live underground on roots.

PARTHENOGENESIS.—Returning to the various kinds of peculiarities we have enumerated on the preceding page, we may remark that the phenomena of parthenogenesis have been thoroughly established as occurring in Aphidae since Bonnet discovered the fact 150 years ago; and though they have not been investigated in much detail it is known that the parthenogenesis is usually accompanied by the production of young all of the female sex. In other cases males are parthenogenetically produced; but whether these males come from a female that produces only that sex is not yet, so far as the writer knows, established. A note by Lichtenstein[518] suggests that usually only one sex is produced by a parthenogenetic female, but that both sexes are sometimes so produced. There is not at present any species of Aphid known to be perpetuated by an uninterrupted series of parthenogenetic generations. It was formerly supposed that there are no males at all in _Chermes_, but, as we shall subsequently show, this was erroneous. It has, however, been observed that a series of such generations may be continued without interruption for a period of four years, and we have no reason to suppose that even this could not be much exceeded under favourable conditions. The parthenogenetic young may be produced either viviparously or oviparously, according to species.

OVIPAROUS AND VIVIPAROUS REPRODUCTION.—The distinction between these two processes has been extensively discussed, some naturalists maintaining that they are thoroughly distinct _ab initio_. This view, however, cannot be sustained. The best {584}authorities are agreed that in the earliest processes of individualisation the ovum, and the pseudovum[519] giving rise to a viviparous individual, are indistinguishable. Leydig, Huxley, Balbiani, and Lemoine are agreed as to this. Nevertheless, differences in the development occur extremely early. The nature of these differences may be briefly described by saying that in the viviparous forms the embryonic development sets in before the formation of the egg is properly completed. Balbiani says, "In fact at this moment [when the viviparous development is commencing] the germ [pseudovum] is far from having obtained the development it is capable of, and from having accumulated all the matter necessary for the increase of the embryo, so that the evolution of the former coincides, so to speak, with that of the latter. On the other hand, in the true ovum the two processes are chronologically separate, for the rudiment of the new individual never appears before the egg has completed the growth of its constituent parts."[520] As regards the difference in structure of the organs of viviparously and oviparously producing individuals, it is sufficient to remark that they are not of great importance, being apparently confined to certain parts remaining rudimentary in the former. Leydig, indeed, found an _Aphis_ in which certain of the egg-tubes contained eggs in various stages of development, and others embryos in all stages.[521]

As regards the physiology of production of winged and wingless individuals there has been but little exact inquiry. Vast numbers of individuals may be produced without any winged forms occurring, while on the other hand these latter are occasionally so abundant as to float about in swarms that darken the air; the two forms are probably, however, determined by the supply of food. The winged forms are less prolific than the apterous forms; and Forbes has noticed in _Aphis maidi-radicis_, where the generations consist

## partly of apterous and partly of winged individuals, that when the corn

begins to flag in consequence of the attacks of the _Aphis_, then the proportion of {585}winged individuals becomes large.[522] The appearance of winged individuals is frequently accompanied by a peculiar change of habit; the winged individuals migrating to another plant, which in many cases is of a totally different botanical nature from that on which the apterous broods were reared: for instance _Aphis mali_, after producing several apterous generations on apple, gives rise to winged individuals that migrate to the stems of corn or grass, and feeding thereon commence another cycle of generations. The study of this sort of Aphis-migration is chiefly modern, but many very curious facts have already been brought to light; thus _Drepanosiphum platanoides_, after producing a certain number of viviparous generations on maple (_Acer_), quits this food-plant for another, but after two or three months returns again to the maple, and produces sexual young that lay eggs.[523] Histories such as this are rather common. Even more interesting are the cases of those species that, after some weeks of physiological activity on a plant, pass into a state of repose on the same plant, and then after some weeks produce sexual young. On the whole, it would appear that the appearance of winged forms is a concomitant of decreasing nutrition. It is a very remarkable fact that the sexually perfect females are invariably apterous, and this is frequently also the case with the males. It is also highly remarkable that the sexually perfect individuals are of comparatively small size. There are at least three kinds of males in Aphidae—1, winged males; 2, wingless males with mouth well developed; 3, wingless small males with mouth absent. As regards some of these points the conditions usual in Insect life are reversed.[524] Huxley inclined to treat all these products of a fertilised egg, that are antecedent to another process of gamogenesis (_i.e._ production with fertilisation), as one zoological individual: in that case the Aphis zoological individual is winged before attaining the mature state, and is wingless and smaller when mature. Some species may have as a rule two, others three, winged generations in a year.

{586}[Illustration: Fig. 285—_Chermes abietis_; hibernating female or "winter-mother." Europe. Much magnified. (After Cholodkovsky.)]

PARALLEL SERIES.—In certain cases individuals of one generation assume different habits, and so set up the phenomenon known as parallel series. This has been recently investigated in the genus _Chermes_ by Blochmann, Dreyfus, and Cholodkovsky. This latter savant informs us[525] that a wingless parthenogenetic female of _Chermes_ hibernates on a fir-tree—_Picea excelsa_—and in the spring lays numerous eggs; these hatch, and by the effects of suction of the _Chermes_ on the young shoots, galls are formed (Fig. 286), in which the Insects are found in large numbers; when they have grown the galls open, and allowing the Insects to escape these moult and become winged females. They now take on different habits; some of them remain on the _Picea_, lay their eggs thereon, and out of these there are produced young that grow into hibernating females, which next spring produce galls as their grandmothers did; but another portion migrates to the Larch (_Larix_); here eggs are laid, from which proceed wingless parthenogenetic females, that hibernate on their new or secondary plant, and in the following spring lay their eggs and give rise to a dimorphic generation, part of them becoming nymphs and going on to the winged condition, while the other part remain wingless and lay eggs, that give rise to yet another wingless generation; in fact, a second pair of parallel series is formed on the new plant, of which one is wingless, and exclusively parthenogenetic, and continues to live in this fashion for an indefinite period on the secondary plant, while the other part becomes winged; these latter are called sexuparous, and go back to the _Picea_, and there lay eggs, that give rise to the sexual forms. If we would summarise these facts with a view to remembering them, we may say that a migration of a part of a generation from the _Picea_ was made with a view of producing a sexual generation, but that only a portion of the migrants succeeded in effecting the object of the migration, and this only in their third generation. Thus portions remained on the _Picea_, {587}producing unisexual (female) individuals, and a portion of those that emigrated to the _Larix_ remained thereon, producing also unisexual (female) individuals, while the others returned to the _Picea_ and produced a sexual generation. How long the production of the unisexual generations may continue has not been determined.

_Phylloxera._—The _Phylloxera_, that has caused such an enormous amount of damage in the Old World during the last thirty years, is a small Aphid that was introduced from North America into Europe. In North America it is not so injurious as it is in Europe, owing, no doubt, to slight distinctions in the conditions of life in the two hemispheres, as one of which may be mentioned that in Europe a larger proportion of the individuals produced appear to confine themselves to feeding on the roots, _P. vastatrix_ being one of the species that lives both in galls on leaves, and underground on the roots. The species is one that exhibits in their most complex form the peculiar phenomena of Aphid life we have already mentioned. It has probably only one congener, _Phylloxera quercus_, and of this Lichtenstein says that in its cycle, from the starting-point of the winter-egg to the assumption of the sexual condition, it exhibits a series of no less than twenty-one forms.[526] The life of _Phylloxera vastatrix_ apparently differs essentially from what we have described in _Chermes_, inasmuch as the migrations are only between leaf and root of the same plant—the vine—and not from one species of plant to another. Some authorities treat _Phylloxera_ and _Chermes_ as a separate family under the name of Phylloxeridae.

[Illustration: Fig. 286—Gall, or false cone of _Chermes abietis_. Cambridge. The small figure, to the left, is a section made at the level indicated by the pointing line _a_, and shows the chambers containing young.]

_Galls._—Like _Phylloxera_, many species of Aphidae live partially, others wholly, in galls that are produced by plants as the result of one or more Aphids interfering with a delicate part of the plant when it is in a young and growing state. The usual position of Aphid galls is on a leaf or leaf-stalk. But in the case of the genus _Chermes_, {588}a bud or some growing part of the spruce-fir is affected in such a way that it gives rise to an object having externally the appearance of a little fir-cone, while inside it consists of chambers in which the Aphids reside. The forms of Aphid-galls are very diverse, but this is probably due to the plant rather than to the Insect, for the same species of Aphis may give rise to different forms of galls. Réaumur thought that each Aphid-gall was due to a single individual that irritated the tissue of the plant, so that the latter grew up at the point of irritation and enclosed the Insect.

A few points as to the anatomy of Aphids should be noticed. It is doubtful whether the antennae have ever really more than six joints, the apparent seventh joint being actually a sort of appendage of the sixth. The rostrum is externally three-jointed, and is remarkable for the great diversity in its length, sometimes it is quite short, at others several times longer than the body (Fig. 285); the setae are often very much longer than the sheath; in cases where this great length of rostrum exists, the individual may often be found with the tip firmly fixed in the bark, and, as it were, tethered by means of the rostrum, the length of which allows, nevertheless, considerable locomotion. Suction is performed by contractions of the pharynx. There has been much difference of opinion as to whether there is a salivary syringe, and Witlaczil failed to find it. Krassilstschik is, however, positive that it exists,[527] and that it is analogous to that described by Mayer in _Pyrrhocoris_, but there are great differences of structure between the two. It is very difficult to determine the number of segments at the extremity of the body; this is terminated dorsally by a median organ placed above the anus, and known as the cauda. Balbiani apparently considers that there are ten abdominal segments and the cauda. The alimentary canal has a small stomach, and an elongate intestine, the terminal division of which is capacious and remarkably long. There are no Malpighian tubes; according to Kowalevsky, their function is discharged by the posterior part of the alimentary canal. There exists, however, a peculiar structure, the pseudovitellus, a sort of cellular, double string; and Witlaczil, in his valuable paper[528] on the anatomy of Aphidae, suggests that this {589}organ may in some way replace the missing Malpighian tubes. Another highly peculiar structure is the siphons, frequently called nectaries, honey-tubes, or siphuncles. They are situated on the dorsal aspect of the fifth abdominal segment, but exist only in certain of the sub-families; they are of very different lengths according to the species, and are capable of movement; they open directly into the body cavity, though exceptional openings into the body cavity are extremely rare in Insects. They excrete a waxy matter, which first appears as oil-like globules. It was formerly supposed that they were the means of secreting the sugary matter, called honey-dew, so much prized by ants and some other Insects; but this is now ascertained to be erroneous. This matter comes from the alimentary canal, and is secreted in large quantities by some species, Büsgen having observed that forty-eight drops, each about 1 mm. in diameter, were emitted by a single individual in twenty-four hours.[529] Certain gall-dwelling Aphidae—_Pemphigus_, _Chermes_ (Fig. 285), _Schizoneura_—possess numerous wax glands; these seem to replace the siphons, and excrete the peculiar, whitish flocculent matter that is so conspicuous in some of these Aphids.

Earlier anatomists failed to find any dorsal vessel, and it is consequently reported in books to be absent. It has been, however, recently detected by Witlaczil, and Mordwilko states that it does not differ from that of other Insects.

We have already alluded to the fact that the mode of reproduction of Aphids leads to an unrivalled increase. This, however, is not due to the prolificness of the individual, which, in point of fact, appears to be considerably below the average in Insects, but rather to the rapidity with which the young begin to reproduce. This has been discussed by Huxley, Buckton, and others. The first-named naturalist calculated that the produce of a single _Aphis_ would, in the course of ten generations, supposing all the individuals to survive, "contain more ponderable substance than five hundred millions of stout men; that is, more than the whole population of China."[530] It has since been contended that Professor Huxley's calculation was much below the mark. Although it is somewhat difficult to make a calculation dealing adequately with the actual facts, yet it is clear that the increase {590}of Aphids is such that, drawing as they do their nutriment directly from the plant in its growing state, in the course of two or three years there would be no nutriment available for other animals, except such as might be derived from plants not attacked by Aphids. The numbers of Aphidae would be so great that they could not be expressed by ordinary numerical methods, and their increase would be actually limited only by the relations existing between different kinds of plants, and between plants and Aphids. This result is avoided by the fact that Aphids are themselves the victims of a whole army of Insect enemies. They have the numerous members of a special group (Braconidae, Aphidiides) of minute Hymenoptera to live inside their bodies, and many Aculeate Hymenoptera depend entirely on the Aphidae as the source of food for their own progeny. The Lady-birds—Coccinellidae—live on Aphids and Coccids, and themselves increase to such an extent as to be in many years a conspicuous part of the Insect world. Crowds of the larvae of Hemerobiids and Syrphids are constantly engaged in spearing and sucking the Aphides. Hence the old naturalist Bonnet said that, just as we sow grain for our benefit, Nature has sown Aphids for the benefit of multitudes of different Insects. He might have added that these different Insects are for the benefit of man, it being clear that without them the population of the world must rapidly decrease.

Ants treat Aphidae more intelligently than most other Insects do, for they do not destroy the helpless creatures, but utilise their products in the way man does those of the cows he keeps. The relations between ants and Aphids is itself an extensive chapter in Natural History; many facts have been brought to light showing that the ants manage the Aphids in a prudent or intelligent manner, distributing them when too numerous in one place, keeping guard over them, even building shelters for them, and in some cases keeping them in direct association, by retaining the Aphids in their own dwellings. The further investigation of these points goes, the more it tends to raise the actions of the ants to the level we call in ourselves intelligent. It would even appear that the ants are acquainted with the migrations of the Aphids from one species of plant to another, Webster informing us that as the Aphis-population on an apple tree multiplied the ants in attendance anticipated their migration to wheat and grass {591}by carrying them to those plants.[531] We have nearly 200 species of Aphidae in Britain,[532] and there may perhaps be 800 known altogether. To what extent they may occur in the tropics is undetermined. There are said to be no native species in New Zealand.

[Illustration: Fig. 287—Instars of _Aleurodes immaculate_. Europe. (After Heeger.) A, Nymph, from above; B, nymph, under surface; C, imago.]

FAM. 8. ALEURODIDAE.—_Minute Insects, with four mealy wings, seven-jointed antennae, two-jointed feet, terminated by two claws and a third process._ These minute Insects are at present a source of considerable perplexity, owing to the curious nature of their metamorphosis, and the contradictory accounts given of them. In the earlier stages they are scale-like and quiescent, being fixed to the under side of a leaf. The French authors Signoret and Girard state that the young are hatched having visible appendages and segmentation, but that after they are attached to the leaf the organs gradually suffer atrophy. Maskell states the opposite, saying that the organs in the earliest stages are not usually recognisable, but become faintly visible with the growth of the Insect. Heeger states that the larva undergoes three ecdyses, and he gives the figures we reproduce; if he be correct it would appear that the nymph undergoes a great development. Réaumur, on account apparently of their great metamorphosis, treated the species {592}known to him as being Lepidopterous, though he correctly pointed out their distinctions. At present we can only conclude that the Aleurodidae undergo a metamorphosis of a kind peculiar to themselves, and requiring renewed investigation. The family has been monographed by Signoret, and more recently by Maskell, who has increased the number of species to about sixty.[533] We have three or four in Britain, one of which, _A. brassicae_, is extremely abundant on various kinds of cabbage in certain years.

[Illustration: Fig. 288—Scale-Insect. A, _Aspidiotus camelliae_, on the stem of a plant; B, a female scale magnified. (After Green.)]

FAM. 9. COCCIDAE (_Scale-Insects_, _Mealy-bugs_).—_Insects, usually minute, with only a single claw to the foot; the male with one pair of wings, but without mouth-parts; the female wingless and usually so degraded in form that most of the external organs and appendages cannot be distinguished._ The form in which these Insects are most generally known is that of a small scale or shell-like body closely adhering to leaves, fruits, or bark. The scales are of the most varied form, so that no general description can be given of them. The scale may be defined as an accumulation of excreted matter, combined with the cast skin or skins of the Insect, covering the body either totally or partially, and thus acting as a shield under which the subsequent development takes place. All Coccidae do not form scales; but the habit of excreting a large quantity of peculiar matters to the outside of the body is universal; this excreted substance is frequently white, and of a powdery nature, and Coccids of this kind are known as mealy-bugs. In other cases the exudation is like shell or glass, and the creature may become quite encysted therein. In this way the forms of Cocidae known as "ground-pearls" are formed. When first hatched from the egg Coccidae are mite-like creatures, and it is only subsequently that the females lose the power of locomotion. The females of numerous forms of Coccidae—more particularly the mealy-bugs—do not lose the antennae and legs. There is also a group (Brachyscelides) of Coccids that live in {593}galls. This highly aberrant group is, however, peculiar to Australia; elsewhere very few gall-making Coccids have been discovered.

[Illustration: Fig. 289—_Dactylopius longispinus._ Female on portion of a fig-leaf. (After Berlese.)]

There are upwards of 800 species of Coccidae at present known.[534] The family was monographed by Signoret about twenty-five years ago, and since then there has been very much matter concerning them published in a scattered manner.[535] No general work has been published on the British species, but Mr. Newstead is preparing one. The classification of Insects so minute as Coccidae, and with such extreme difference in the sexes, is, of course, a matter of great difficulty; the best divisions are those given by Green in his _Coccidae of Ceylon_.[536]

The fact that there is only one pair of wings in the perfect male Coccid would appear to ally these Insects with the Diptera; these Coccidae have, too, like the Diptera, a small appendage on each side of the metathorax. Witlaczil shows that these little processes may really represent a pair of wings, inasmuch as they are developed from imperfect folds of hypodermis, _i.e._ imaginal discs. Beyond these facts and the occurrence in certain females (Margarodes) of a great histolysis during the post-embryonic development, there is nothing to indicate any relationship between Coccidae and Diptera. It has been shown by Riley that these little processes, in some forms, serve as hooks to attach or control the true wings, and this function is never assumed by the halteres of Diptera. Although Coccidae are placed next Aphidae, yet the two families appear to be really very different. The modes of reproduction so peculiar in Aphidae reappear to a certain extent in Coccidae, but are associated with profound {594}distinctions. Though the viviparous method of reproduction and parthenogenesis occur in Coccidae, yet they are only exceptional, and they are not put to the same uses by the species that exhibit the phenomena. Thus we have seen that in Aphidae generations of imperfect individuals are produced with rapidity, while the individual is not directly very prolific. In Coccidae the reverse is the case—the generations are usually similar to one another; they do not, as a rule, follow with rapidity, and the female is usually very prolific, thousands of young being sometimes produced by a single individual. The extraordinary polymorphism of the species of Aphidae is not exhibited by Coccidae, though, contrary to what we find in Aphidae, the males and females are usually excessively different. The two families apparently also differ in that Coccidae are specially characteristic of warm climates, Aphidae of the temperate regions.

PARTHENOGENESIS.—Owing to the fact that the males are very minute creatures, totally different from the females, and living but a very short time, they were but little known to the earlier observers. It was therefore only natural to suppose that parthenogenesis was very common. Of late years the males of a great many species have become known, so that ordinary sexual reproduction must be considered as the normal method in Coccidae, although, in the great majority of cases, the male is still unknown. It has, however, been shown in numerous cases that parthenogenesis may occur even when males exist; and there are some abundant species of which it has not been possible to find a male. In 1887 Moniez[537] announced that he had discovered the male of _Lecanium hesperidum_ (one of the notoriously parthenogenetic species) in an ovarian cul-de-sac in the body of the female, and he therefore considers that sexual reproduction occurs. He does not say how pairing takes place, and we are not aware that his observation has been confirmed. If correct it will be necessary to reconsider the whole question as to parthenogenesis in Coccidae. Apterous males are known in two or three species.

The post-embryonic development of Coccidae is of the most unusual character. It is quite different in the two sexes, and in each of them it presents features not found elsewhere. It has, however, as yet been studied in only a few forms, and even in them is incompletely known.

{595}[Illustration: Fig. 290—Instars of _Dactylopius citri_. (After Berlese.) A, Egg; B, young larva; C, first male nymph; D, second male nymph; E, adult male; F, adult female. All equally magnified. x 20.]

When hatched from the egg the young Coccids are all similar, male and female being indistinguishable. A difference soon appears, with the result that the male, after passing through more than one pupal condition, appears as a winged Insect. The female never becomes winged, but, if we may judge from the incomplete accounts we at present possess, her development varies much according to species. In some she retains the legs, antennae, and mouth-organs; in others she loses these parts, though retaining the original form in a general manner; while in a third (_Margarodes_) she becomes encysted, and apparently suffers an almost complete histolysis, reappearing after a very long period (it is said it may be as much as seven years) in a considerably altered form. The post-embryonic development of _Aspidiotus nerii_ has been studied by Schmidt[538] and Witlaczil,[539] whose accounts agree except as to some points, such as the number of ecdyses. The young, or larva, is hatched with fairly well-developed legs, antennae, and rostrum; there is no external difference between the sexes. The larva selects some spot on the plant and drives its rostrum therein, thus becoming fixed; moults occur, and the body excretes waxy matter from its sides in processes that fell together and form the shield; the female becomes much larger than the male. The legs and antennae of both sexes disappear, so that the power of movement is completely lost. The mouth-parts also atrophy. The female after this undergoes no further change, except that of growth in connection with ovarian development.

{596}[Illustration: Fig. 291—Development of male of _Aspidiotus nerii_. A, Newly hatched larva; B, prae-pupal instar; C, pupa before ecdysis; D, pupa shortly before the emergence of the imago: _a_, antenna; _e_, eye; _f_, wing-rudiment; _l_, leg; _o_, basal part of mouth-organs. (After Schmidt.) Magnification not definitely stated.]

The male, however, continues development; notwithstanding the impossibility of taking food, owing to the absence of a mouth, it increases much in size, and the organs of the future perfect Insect commence to develop from imaginal discs in a manner similar to that which occurs in the Dipterous genus _Corethra_; no mouth-parts are however developed, these being merely represented by spots of pigment, or rudimentary additional eyes. The wings are developed outside the body. Difference of opinion prevails as to the nature of the instars between the young larva and the imago. It is clear, however, that Fig. 291, D, corresponds fairly with the pupa of Insects with complete metamorphosis, and the instars shown in Fig. 291, B, C, may therefore be looked on as equivalents of the resting-larva stage of ordinary Insects with complete metamorphosis. Witlaczil considers this development to be a condition of incomplete, approaching very nearly to complete, metamorphosis. The condition is perhaps more precisely estimated if we recollect that winged Insects are divided into two series, in one of which the wings are developed outside the body; in the other, inside the body. The Insects with very complete metamorphosis all belong to the second of these two series, while in the male Coccid we have the highest form of metamorphosis attained by any of the first series. As regards the development of the female encysted nymph or pupa, previously alluded to as being found in the "ground-pearls" of {597}the genus _Margarodes_, we can at present offer the reader no satisfactory account.[540]

PRODUCTS OF COCCIDAE.—Honey-dew is secreted by Coccidae, but as a rule not so extensively as by Aphidae and some other Homoptera; nevertheless, it is often sufficient to make the plants frequented by Coccids very sticky and unclean. Some species make a really extensive exudation of such matter. Réaumur records that a Coccid, which is doubtless _Lecanium persicae_, excretes a supply of honey-dew that drips to the ground; he says it tastes sweet and nice. The manna mentioned in the book of Exodus is pretty certainly the honey-dew secreted by _Coccus_ (now _Gossyparia_) _mannifera_, which lives on _Tamarix_ in many places in the Mediterranean basin. This substance is still called by the Arabs "Man," and is used as food; in its natural state it is a substance very like honey; it is doubtless excreted by the _Coccus_, and is not produced directly by the _Tamarix_ as some have supposed. Waxy matters are produced by several Coccidae. _Ceroplastes ceriferus_, a Lecaniid, produces white wax in India. _Ceroplastes_ is a widely distributed genus, and various species of it have been used for the purpose of producing wax in other parts of the world. The white wax of China is understood to be produced by another Lecaniid, _Ericerus pela_; but little is known as to this Insect; it is said that the wax is produced by the winged males. The substance was formerly greatly prized in China, but is falling into disuse on account of the introduction of Kerosene. Lac is produced by _Carteria lacca_, a Lecaniid living in India on _Anona squamosa_, as well as on species of _Ficus_, _Rhamnus_ and other trees; the lac is the shelly scale produced by the Insect as a covering; it is composed in larger part of resinous matter, with which there is mixed a comparatively small quantity of wax and other substances. The body of this Insect also affords the red substance called lake. Various species of _Kermes_ formerly afforded a red dye well known to the Greeks and Romans. These Insects live on _Quercus coccifera_ in the Mediterranean region. A medicinal syrup is also obtained from them. _Porphyrophora polonica_ was used in North and Central Europe for the same purposes as _Kermes_; it is a Coccid living on the roots of _Polygonum cocciferum_. These European Insects were replaced commercially {598}after the discovery of America by the cochineal Insect, _Coccus cacti_, a Mexican Coccid feeding on a Cactus called Nopal (_Opuntia coccinellifera_). This Insect was subsequently introduced to the Eastern hemisphere, and was established with more or less success in a few spots on the borders of the Mediterranean. In the Canary Islands it flourished on other species of _Cactus_, became acclimatised, and was the object of an extensive commerce. The colour in the case of all these Coccid dyes was obtained from the bodies of the Insects, in the tissues of which it is contained. The dyes have now been largely displaced in commerce by the derivatives of Aniline. Axin is produced by the Mexican Coccid _Llaveia axinus_; this substance appears to be of a very peculiar nature; it is apparently chiefly fatty, and contains a peculiar acid, axinic acid. Axin is used as an external medicinal application in various affections; and it is also employed as a varnish; it dries and hardens on exposure to the air, and is said to be of considerable value.[541] In our British genus _Orthezia_ the body of the female is completely covered with a symmetrical snow-white armour, from which project the pink legs and antennae. This is one of the forms in which the female preserves the legs to the end of her life. The objects called ground-pearls, already alluded to, have long been known in various parts of the world, and in the island of St. Vincent they are sufficiently large to be collected and strung for necklaces. These bodies are the encysted pupae of Coccids of the genus _Margarodes_; the cyst is said to be of chitin. _M. vitis_ commits serious ravages on the vines in Chili by sucking their roots, and it is probable that all the species are of subterranean habits; this would partially explain the fact that very little is known about the history of these pearls, though naturalists have been acquainted with them for many years.

The gall-making Coccids of the group Brachyscelides have only recently been at all investigated; the galls they give rise to are sometimes about a foot in length, and there appear to be numerous species and several genera in Australia; they are especially abundant on _Eucalyptus_ and Acacias. The females are highly remarkable from the variable conditions the legs assume, so that in some cases they may be described as biped Insects, the {599}hind legs remaining, though the others have atrophied.[542] Very little indeed is known as to these Insects. One of the most peculiar points of their economy appears to be that the galls giving rise to males are different from those producing females.

ANOPLURA or LICE.

[Illustration: Fig. 292.—_Pediculus capitis_, ♀. Human head. (After Piaget.)]

_Small Insects with thin integument; entirely wingless, the three thoracic segments indistinctly separated; the head bearing in front a short tube furnished with hooks; from which tube there can be protruded another very delicate sucking-tube. Feet terminated by a single long claw._ The Anoplura, Pediculidae, or lice are disgusting Insects about which but little is known. The most contrary opinions have been expressed as to their mode of taking their nourishment, which is, without exception, the blood of Mammals; on the bodies of which they pass the whole of their life. It is a most difficult matter to examine their mouth; the best information on this point is given by Schiödte and Graber, but though these two authorities agree, their results are very incomplete, and do not warrant us in expressing a confident opinion as to the nature of the relationship between Hemiptera and Anoplura—a question that has been for long a moot one. The short tube furnished with hooks in front (Fig. 293, _d_) is considered to be the lower lip, and the tube inside is, it is suggested, a combination of the homologues of maxillae and mandibles; there is also what may be a labrum (_g_); and inside the head a framework, at any rate analogous to if not homologous with, the parts of this kind we have described as existing in Hemiptera. All the parts, with the exception of the basal tube or head of the beak, are of the most minute and delicate nature, so that it is difficult to see their form or comprehend their relations. It is evident that they are very different anatomically from the mouth-parts of Hemiptera; still there is {600}sufficient general resemblance to warrant the belief that the parts in the two may ultimately be shown to be also morphologically similar. If Meinert be correct, this view will, however, not prove to have any foundation. He considers that morphologically the mouth of the louse has no similarity to that of the bug; the protrusible parts in the former he considers to be modifications of epipharynx and hypopharynx; and the rod-like structures to be hypopharyngeal lamellae; and that they are thus totally different from the setae of bugs.[543] He considers Lice to be a distinct Order of Insects for which he proposes the name Siphunculata.

The alimentary canal and nervous system resemble those of Mallophaga more than they do those of Hemiptera. The oesophagus leads into a large stomach bilobed in front; at the posterior extremity of this there open the four Malpighian tubes, and behind these there is a well-marked small intestine. The nervous system consists of a cephalic ganglion and of three other closely approximated ganglia, the posterior one the larger. It remains doubtful whether or not the first of these three ganglia is the infra-oesophageal one.[544]

[Illustration: Fig. 293.—Mouth-organs of louse. (After Graber.) _b_, _c_, Chitinous envelope into which the beak can be withdrawn; _d_, head of the beak, with crown of spines; _g_, labrum; _h_, delicate tube protruded (very rarely seen in this state); _m′_, unpaired muscle.]

The species of lice, so far as known, are not numerous, some six genera and about forty species being all that are recorded; they occur on various kinds of mammals, including some that live in water. Seals have a genus, _Echinophthirius_, peculiar to them. Monkeys are specially liable to be affected by lice; the genus that chiefly occurs on them is _Pedicinus_, a very distinct one, in which there are only three instead of five joints to the antennae. Perhaps the most remarkable louse is _Haematomyzus elephantis_, that of the elephant; it has a long proboscis in front of the head. As a rule each species of louse is confined to one species of Mammalia, or to very closely allied forms. Man is said to be infested {601}by three species, _Pediculus capitis_, _P. vestimenti_ and _Phthirius inguinalis_; Meinert is of opinion that _P. capitis_ and _P. vestimenti_ are only one species, and Schiödte appears also to have thought this probable. Andrew Murray was of opinion that the heads of different varieties of men are infested by distinct varieties of _P. capitis_. His conclusion was chiefly based on examination of specimens preserved by Charles Darwin; it requires confirmation. Very little is known as to the life-history of the louse. Leeuwenhoek made himself the _corpus vile_ for an experiment, from which he concluded that the _Pediculus vestimenti_ is very prolific. That scientific men did not know whether the louse bites or sucks was formerly made the ground for a taunt. Schiödte has given an almost pleasing account of the way in which he settled this,[545] showing that the sucking action is beyond all doubt. Accounts of disease called Phthiriasis, attributed to lice, are to be found in many old books, but the evidence does not warrant us in believing anything more than that persons suffering from some disease, and in a neglected and filthy condition, were horribly infested with these disgusting Insects.

It is usual to say that Pediculidae are Hemiptera degraded by a long exclusive persistence in parasitic habits. At present, however, this must be looked on as a pious opinion, rather than as an induction from our knowledge of their morphology and embryology; for this is at present too imperfect to warrant any final conclusion.

{602}NOTES AND CORRIGENDA

VOL. VI.

Note to P. 4: _Classification of Hymenoptera._ Mr. W. Ashmead has published[546] a sketch of a new classification of Hymenoptera, in which the points we have suggested are given effect to; the first division of the Petiolata being carried out with reference to the position of the ovipositor, while part of the Proctotrypidae is brought into the Aculeate division. We cannot, however, commend this arrangement as final, for several points have not received sufficient consideration.

Note to P. 172, line 22. For the words "We shall subsequently see," substitute "We have previously said" (p. 161).

Note to P. 350, line 10 from bottom: _instead of_ "only one genus," _read_ "only one Old World genus."

Note to P. 541, line 16: _instead of_ "two" _read_ "ten."

VOL. V.

P. 217, line 4. _For_ sterna _read_ nota.

P. 271. The lettering of Fig. 158 is erroneous; under the lower pointing line the letter d should be inserted, and the left hand upper pointing line should bear the letter c _instead of_ d.

P. 277, line 7. _Instead of_ Fig. 162, _read_ Fig. 163; and line 9, _instead of_ Fig. 163 _read_ Fig. 164.

P. 378. The species figured has since been described by Mr. Haviland as _Termes malayanus_.

P. 380. The species figured has since been described by Mr. Haviland as _Termes mirabilis_.

P. 383. _Hodotermes japonicus._ It has been recorded (_P. Boston Soc._ xii. 1869, p. 139) that this is not a Termite, but an immature form of the earwig _Brachylabis maritima_.

Pp. 480 and 481. It is not made clear that the distinction in the number of joints of the palpi of Phryganeides and Limnophilides applies to the males only; in both groups the number of joints in the females is five. The remark as to Phryganeides occurring in the Southern Hemisphere is erroneous. It is Limnophilides that reappear in Chili, not Phryganeides.

P. 490. Fig. 333 A, _f_ and its line point to a division of the mesonotum, not of the metanotum.

P. 564. Habits of _Pelecinus_. Mr. S. A Forbes has recorded an observation suggesting that _P. polyturator_ may be a parasite of Lamellicorn beetles of the genus _Lachnosterna_. See _Rep. Ins. Illinois_, xix. 1896, p. 79.

{603}INDEX

Every reference is to the page: words in italics are names of genera or species; figures in italics indicate that the reference relates to systematic position; figures in thick type refer to an illustration; f. = and in following page or pages; n. = note.

Abdomen, of _Chrysis_, 2; of Coleoptera, 185; of Diptera, 446; of Hemiptera, 538; of Lepidoptera, 313; of Thysanoptera, 528 Abdominal legs, 9 Abeille-perce-bois, 33 Abeille tapissière, 51 _Abispa_, 77 _Acacia fistulosa_, beetles in, 213 Acalyptrate Muscidae, _494_ _Acanthia_, _560_ Acanthomeridae, 483 _Acanthosoma griseum_, 546 Acari, relations to Insects, 220, 223, 238, 530 _Acentropus_, 425 Acephalous larvae, 449 Achreioptera, _219_ Acraeides, 350 _Acridium maroccanum_, 254 _Acrocera globulus_, 490 Acroceridae, 489 _Acronycta_, 418 _Actias luna_, 374

## Actiidae, _510_

Acutilingues, _20_ Adapted excrement, 284, 284, 380 _Adelops_, 221 Adensamer, on _Ascodipteron_, 520 Adephaga, _190_, 200 f., _216_, _234_ Adimeridae, 240 _Adimerus setosus_, 241 Adlerz, on _Formicoxenus_, 160; on _Tomognathus_, 161 Adminicula, 327 _Aëdes_, 455 n. _Aegeria_, 387 Aegeriidae, 386 Aegialitidae, 265 _Aegocera tripartita_, 411 _Aenictus_, 159, _179_, _180_ _Aenigmatias blattoides_, 495 _Aeolothrips fasciata_, 528 Aëpophilidae, 559 _Aëpus_, 206 Aërostatic setae, 408 Aërostats, 449 Aganaidae, 408 Agaristidae, _370_, _371_, 410 _Agdistes_, 426 Agdistinae, _426_ _Agenia carbonaria_, _A. hyalipennis_, 105 _Ageronia_, 354 _Aglycyderes setifer_, 298 Aglycyderidae, 297 Agromyzidae, _504_ _Agrotis_, 415; _A. spina_, 417 Ahuatle, 504 _Alaena_, _350_ _Alaopone_, 179, 180 Alar organs—see Wings, Elytra, Tegmina _Aletia xylinae_, 416 _Aleurodes brassicae_, 592; _A. immaculata_, 591 Aleurodidae, 591 _Alucita_, _426_; _A. polydactyla_, 426 Alucitidae, 371, 426. Alula, 447 _Amara_, 205 Amber, Insects in, 144, 269, 458 _Amblyopone_, 180 Amblyoponides, 132, 180 Ambrosia, 295 _Ambryllis_, 409 _Amicta quadrangularis_, 394 _Ammophila_, 111; _A. affinis_, 111; _A. hirsuta_, 111; _A. holosericea_, 111 Amphicyrtides, _242_ _Amphidasis betularia_, 412, 414 Amphiodont, 193 Amphipneustic, 450 _Amphizoa lecontei_, 207 Amphizoidae, 207 {604} _Ampulex compressa_, 114, 115; _A. ruficornis_, 115; _A. sibirica_, 114 Ampulicides, 114 f., 169 Amycterides, 291 Anal armature, 328, 416 Anal nervures, 318 _Anaphe_, 376 Anaspini, 267 _Anaspis_, 268 Anatomy—see External Structure and Internal Anatomy Anchor-process, 459 Ancient, Lepidopteron, 435—see also Primitive Ancylolominae, _425_ _Andrena_, _23_, 25, 30, 301, 303; hair of, 11; _A. labialis_, 488; _A. nigroaenea_, 23; _A. ovina_, 30 Andrenidae, _20_ Andrenides, 23 _Andrenimorpha_, 388 Andrenoides, _20_ Androconia, 331 f. _Anergates atratulus_, 160 f. Angelitos, 63 _Anisopteryx aescularia_, 411 _Anisotoma cinnamomea_, 222 Anisotomidae, _223_ Anisotomides, 222 Anlagen, 143 Anobiides, 247 _Anobium_, 254; _A. paniceum_, 247; _A. striatum_, 248; _A. tessellatum_, 248 _Anochetus ghiliani_, 174 _Anomma_, 178 _Anophthalmus_, 205 Anoplura, 599 f. _Anosia erippus_, _A. menippe_, 345; _A. plexippus_, 307; larva, 324; pupa, 327 Antennae; of _Belostoma_, 566; of flies, 441; of Lamellicornia, 191; of Lepidoptera, 307; of butterflies, 340, 341; of Sphingidae, 380 _Antherophagus_, 235 Anthicidae, 266 _Anthidium_, 45; _A. bellicosum_, 47; _A. diadema_, 45; _A. manicatum_, 45; _A. septemdentatum_, 47; _A. strigatum_, 30 _Anthocopa_, 51 Anthocoridae, _560_ _Anthomyia angustifrons_, _A. brassicae_, _A. cana_, 506 Anthomyiidae, 506 Anthophila, 10 f. _Anthophora_, 32, 33; destroyer of, 272, 274; _A. personata_, 33; _A. pilipes_, 33; proboscis of, 17 _Anthothrips aculeata_, 530 Anthracides, 486 _Anthrax_, 486 f.; _A. fenestralis_, 489; _A. trifasciata_, 44 _Anthrenus fasciatus_, 241 Anthribidae, 278, 290 Antisquama, 448 Antitegula, 447 Ant-plant, 138, 139, 168 Ants, 131 f.; and Aphidae, 590; and caterpillars, 356 Ants'-nest, Insects, 200, 213, 221, 223, 224, 225, 231, 236, 240, 548; larva, 501, 502 Anus, 314, 320 Aorta, 320 Aortal chamber, 320 _Apate capucina_, 246 _Apatela_, 418 _Apathus_ = _Psithyrus_, q.v. Apatidae, 246 _Apatura_; larvae, 354; _A. iris_, 344 Apaturides, 352 _Aphaenogaster_, 164, 165, 221; _A. arenarius_, 164; _A. barbarus_, 131, 164; _A. structor_ 164, 240 Aphaniptera, 522 f. _Aphanocephalus_, 228 _Aphelocheirus_, 565 Aphidae, 581 f.; and ants, 181 Aphidiides, 590 _Aphis maidi-radicis_, 584 _Aphomia sociella_, 424 Apidae, 10 f., 20, _32_ Apioceridae, 492 _Apis_, _53_; _A. adansonii_, 69; _A. domestica_, 68; _A. dorsata_, 69; _A. fasciata_, _A. ligustica_, 68; _A. mellifica_, 65 f.; feet of queens and workers, 69; ligula of, 16; worker and hairs, 12 _Apoda_, 402; _A. testudo_, etc., 401, 402 Apodidae, 402 _Apoica pallida_, nest, 83 _Aporia crataegi_, 322 Appetite, 491 _Apterogyna_, 96 _Apterona_, 393, 394; _A. crenulella_, var. _helix_, 395 Apterous, beetles, 187, 263; females, 95, 96, 140, 171, 174, 315, 392, 393, 407, 413, 430, 592—see also Workers; Insects, 95, 96, 474, 495, 496, 505, 518, 531, 581; males, 140, 160, 161, 172, 585, 594 Aquatic; caterpillar, 377; cocoons, 280; larva, 421 f., 425, 504; pupa, 423 Aradidae, 550 _Aradus orientalis_, 550 _Araeocerus_, 290 _Araschnia levana_, _A. prorsa_, 353 Arbelidae, _369_, 396 _Arceina_, 373 Archiapidae, _21_, _22_ Archiapides, _21_ f. _Arctia caja_, 308; _A. villica_, 410 Arctiidae, _370_, _404_, 408, _410 Argiva_, 414 {605} _Argynnis_, larvae, 354; _A. paphia_, androconia, 332 _Argyromoeba sinuata_, 76; _A. trifasciata_, 486 Arista, 442 Army-worm, 416 _Aromia moschata_, 188 _Arthropterus_, 214 _Asclera caerulea_, 267 _Ascodipteron_, 520 _Asemorhoptrum lippulum_, _160_ Asilidae, 491 _Asilus_, 492; _A. crabroniformis_, 441 Asparagus-beetle, 281 _Aspidiotus camelliae_, 592; _A. nerii_, 595, development of, 596 _Aspidiphorus_, 246 _Aspidomorpha_, pupa, 283, 284 Association, of _Anergates_ and _Tetramorium_, 160; of ants and other Insects etc., 180 f.; of _Formica_ and _Formicoxenus_, 159; of _Strongylognathus_ and _Tetramorium_, 162; of _Tomognathus_ and _Leptothorax_, 161 _Astata boops_, 119 _Astatides_, 119 Asteidae, _504_ _Astomella lindeni_, 490 _Astynomus_, 285 _Atemeles_, 225; and ant, 182 Athericerous, 441 _Atherix_, 481; _A. ibis_, 480 _Athous rhombeus_, 257 _Atractocerus_, 254 Atrophy of mouth and stomach, 310 _Atta_, 137, 164 n., 165, 502 _Attacus_, 373; _A. atlas_, 373 Attelabides, 291 Attini, 158, 159, 165 Attitude, 381, 384, 385, 388, 412, 413, 425, 429 _Atylotus fulvus_, 483 _Autocrates aenea_, 275 _Automeris_, 373 Axin, 598 _Azteca_, 158 Azygos oviduct, 321

_Badamia exclamationis_, 365 Barrett, on increase of melanism, 414 Basket-worms, 393 Bat-parasites, 521, 560 Bataillon, on metamorphosis, 306 Bates, H. W., on classification of butterflies, 344; on homoeochromatism, 351; on _Megacephala_, 201 Batesian mimicry, 337, 339 _Bathyscia_, 221 Beak, 532 Beauregard, on vesicating Insects, 275 Beaver, Insect on, 219, 221 Becher, on mouth of Diptera, 444 n. Bed-bug, 559; enemy of, 558 Beddard, on animal coloration, 339 n. Bee (_i.e._ honey-bee)—see _Apis mellifica_ Bee-louse or -tick, 520 Bees, 10 f. Bees born of carcases, myth, 499 Bees' nest beetle, 235 Bees, stylopised, 300, 303 Beetles, 184 f. Bellesme, on buzzing, 19 Belostomidae, 534, 565 Bembecidae, 482 Bembecides, 119 f. _Bembex_, 509; _B. rostrata_, 4, 120, 120 f.; _B. spinolae_, 130 n. Benchucha bug, 559 _Berosus_, 218 Berytidae, 548 _Bibio_, 475, 476, 477; _B. marci_, 477 Bibionidae, 475 Birds and butterflies, 338 Biscuit-weevil, 247 _Bitoma crenata_, 233 _Bittacomorpha_, 473 Black-fly, 530 Blanchard, on flies attacking man, 517 n. Blepharoceridae, 464 Blind beetles, 205, 221, 233 _Blissus leucopterus_, 548 Blister-beetles, 269 Blochmann, on founding new nests, 145 Blood-sucking, Diptera, 457; Mosquitoes, 467 Blood-worms, 468 Blow-flies, 511 Blue-bottles, 511 Bogus Yucca-moth, 433 _Boletophila luminosa_, 463 Boll-worm, 416 Bombardier-beetles, 201 _Bombus_, 53 f.; insect in nest of, 221; fleas in nests of, 525; parasite of, 94, 497; proboscis of, 13 f., 14; _B. agrorum_, 54; _B. lapidarius_, 54; _B. muscorum_, 57; _B. variabilis_, 60 Bombyces, _367_ Bombycidae, _368_, 375, 406 Bombyliidae, 485 _Bombylius major_, 488 _Bombyx mori_, 375; _B. yamamai_, 325 Book-worm, 247 Borboridae, _504_ _Borborus_, 505 _Borocera madagascariensis_, 405 Bostrichidae, 246 Bot-flies, 514 Brachelytra, _224_ Brachycera, 441, 454 Brachycerides, 291 Brachyscelides, 592, 598 _Brachytarsus_, 290 Braconidae, 590 {606} _Bradypus cuculliger_, Tineid on, 430 Brahmaeidae, _368_, 374 Brain, 320; cephalic and thoracic, 449 Branchiae, 208, 244 Brands, 332 Brassolides, 349 _Brathinus_, 223 Brauer, on Dipterous larvae, 451; on Oestridae, 514 _Braula coeca_, 520 Braulidae, 520 Breastbone, 459 Breeze-flies, 443, 481 Breitenbach, on proboscis of Lepidoptera, 311 n. Breithaupt, on proboscis of bee, 15; on deglutition of bees, 18 Brenthidae, 295 _Brenthus anchorago_, 297 _Brephos notha_, 415, 416 Brimstones, 357 _Brontes planatus_, 234 Brown-tail moths, 407 Bruchidae, 276 _Bruchus fabae_ and _B. lentis_, 277, _B. pisi_, 277 _Bryophila_, 418 Buckell, on development of pattern, 335 Buffalo-gnats, 477 Bugong-moth, 417 Bugonia-myth, 499 Bull-dog ants, _171_, 173 Bull's-horn thorn and ants, 168 Bumble bee—see _Bombus_ Buprestidae, 261 _Buprestis attenuate_, supposed larvae of, 262 n. Burgess, on suction, 311 Burnet-moths, 390 Burrows, of _Dasypoda_, 27; of _Halictus_, 24, 25; of _Odynerus_, 74 Bursa copulatrix, 321 Burying-beetles, 221 Butterflies, _341_ f. Buzzing, 19 Byrrhidae, 242, _255_ _Byrrhus pilula_, 242 Bythoscopidae, 578 _Byturus_, _241_

_Cadphises moorei_, 391 Calandrides, 289 Calcium oxalate, 406 _Calicurgus_, 101; _C. hyalinatus_, 102, 106 _Caligo eurylochus_, 350 _Callidea baro_, 303 n. Callidulidae, _370_, 400 _Calliphora_; 448; _C. erythrocephala_, _C. vomitoria_, 511 _Callirhipis dejeani_, 256 _Callomyia_, 496 _Callostoma fascipennis_, 489 _Caloptenus_, 270; _C. italicus_, 489, _C. spretus_, 488, 506, enemies of Calypter, calypterate, 448 Calyptrate Muscidae, 448, _504_ Camberwell Beauty, _352_ Camel bot-fly, 515 Camponotides, 144 _Camponotus_, 145; _C. ligniperdus_, 138, 145, 147; _C. pennsylvanicus_, 138, 146; _C. rubripes_, 131; _C. rufipes_, 137 Camptosomes, _279_, 281 Canephorinae, 394, 395 Cantharidae, 269 f. Cantharides, _270_ Capsidae, 561 _Capsus laniarius_, 539 Carabidae, 204 f. Carabides, _206_ Caraboidea, _190_, 200 f. _Carcinocoris_, 554 Carder-bees, 45 f., 45 _Cardiocondyla_, 161 _Cardiophorus_, 258 Carlet, on sting, 6; on sound-organs of _Cicada_, 574 Carnivora, _200_ Carotine, 549 Carpenter-bees, 33 Carpenter-worms, 395 Carpets, 411 _Carpocapsa juliana_, _C. pomonella_, _C. splendana_, _C. saltitans_, 428 _Carpophagus_, 278 _Carteria lacca_, 597 Carus, on paedogenesis, 461 _Caryoborus_, 278 Case, 281, 392, 393, 394, 417, 422, 423, 430, 431 Cassidides, _279_, 283 Caste-production, 142 _Castnia_, 307, 309, 316, 319; _C. eudesmia_, _C. therapon_, 372 Castniidae, _369_, 371 _Castor canadensis_, parasite of, 219 _Cataclysta lemnata_, 423 Caterpillar, 322, 324, 325; of Diptera, 474 _Catopomorphus_, 221 Cauda, 538, 588 Cave-beetles, 205, 221 Cebrionides, _260_ _Cecidipta excoecaria_, 424 _Cecidomyia buxi_, 459; _C. destructor_, 460; _C. tritici_, 460 Cecidomyiidae, 455 n., 458 _Cecropia_, plant and ants, 158 _Cedeocera_, 297 n. Cell, of wing, 317, 318; complete and incomplete, 116 n. Cells, formation of, by bees, 21, 22, 24, 25, 28, 33, 34, 35, 46, 48, 51, 52, 54, 56, 60; earthen, 72, 106; of _Coelonites_, 89 Celyphidae, _504_ {607} _Celyphus_, 505 _Cemonus unicolor_, 128 Cephaloidae, 275 _Cephalomyia maculata_, 515 _Cephaloon_, 275 Cephalothorax, 465; of _Stylops_-larva, 302 _Cephenomyia rufibarbis_, 517 Cerambycidae, _278_, 285 Cerambycides, _287_ _Ceramius_, _89_; _C. lusitanicus_, 89 _Ceranchia_, 374 _Cerapachys_, _175_ n. _Ceratina_, 11, _32_ Ceratocampidae, _368_, 375 Ceratocombidae, 559 Ceratognathini, 194, _195_ _Ceratonema_, 401 _Ceratopogon_, 469; _C. bipunctatus_, _C. pulicaris_, _C. varius_, 470 _Cerceris_, 125; _C. arenaria_, 125; _C. bupresticida_, 125; _C. labiata_, 125; _C. tuberculata_, 126 Cercopidae, 577 _Ceresa bubalus_, _C. taurina_, 577 _Cerocoma schaefferi_, 275 Cerophytides, _260_ _Ceroplastes ceriferus_, 597 _Ceroplatus mastersi_, 463 _Cerura vinula_, 383 Cervical sclerites, 472 _Cetonia_, in ants'-nests, 149; _C. floricola_, 200 Cetoniides, _195_, 199 _Chaerocampa_, 380; recte _Choerocampa_ Chaetophorous, 446 Chaetotaxy, 446 Chafers, 194 f. Chalcosiidae, 391, _420_ _Chalia hockingi_, 394 _Chalicodoma_, 32, 35; _C. muraria_, 30, 35 f., 36, 254, 486; _C. parietina_, _C. pyrenaica_, 39 Change of habit in larva, 301, 431 Chapman, Dr. T. A., on _Chrysis_, 3; on classification of pupae of Lepidoptera, 367; on _Hepialus_, 398; on _Metoecus paradoxus_, 268; on pupa of Lepidoptera, 327 n. _Charagia_, 396 _Chartergus chartarius_, nest of, 82, 83 _Cheilosia chrysocoma_, 439 _Cheimatobia brumata_, 414 _Cheliomyrmex_, _180_ Chelonariides, 242 _Chelonia_, 410 _Chelostoma_, _35_ _Chennium bituberculatum_, 224 _Chermes_, 583, 586, 587; _C. abietis_, 586, 587, 589 Cheshire, on proboscis of bee, 15 Chigger, 525 Child, on sense-organ, 442 China-marks, 421 Chinch-bug, 548 _Chionea araneoides_, 474 Chiromyzidae, 479 Chironomidae, 468, _474_ _Chironomus_, 440, 468 Chlamydes, _279_ _Chlorion_, 110ü Chloropidae, _504_ _Chlorops_, 504 _Choerocampa elpenor_, 380 Choerocampini, 381 Cholodkovsky on _Chermes_, 586 _Choragus sheppardi_, 290 Chorion, 322 Chrysalis, 326, 344 Chrysauginae, 423 Chrysididae, 1 f. _Chrysiridia madagascariensis_, 419 _Chrysis bidentata_, 3; _C. ignita_, 3; _C. shanghaiensis_, 4 _Chrysochus pretiosus_, 279 _Chrysocoris grandis_, 303 n. Chrysomelidae, _276_, 278 f. Chrysomelides, _279_ Chrysopolomidae, 396 _Chrysops_, 482 _Cicada_, 123; _C. plebeia_, 574; _C. septendecim_, 569 Cicadellinae, 578 Cicadidae, 568 f. _Cicindela hybrida_, 202 Cicindelidae, 201 f. _Cicinnus_, _378_ n. _Cilix glaucata_ = _spinula_, 401 _Cimex_, _560_; _C. lectularius_, 559 Cimicidae, 559 Cioidae, 245 _Cis melliei_, 245 Cistelidae, 264 _Cistus salvifolius_, beetle-larvae in, 282 _Cithaerias_, 348 _Citheronia_, 375 Cixiides, _576_ _Cixius_, 575 Clambidae, _223_ Clasper, 314 Classification, of ants, 144; of bees, 20; of butterflies, 341; of Coleoptera, 189; of Diptera, 454 f.; of Hemiptera, 543; of Hymenoptera Aculeata, _10_; of Lepidoptera, 339 f.; of moths, 366 f. Clavicornia, _189_, _213_, 265 _Claviger testaceus_, 224 Clavigerides, 224 Clavus, 539 Clear-wings, 386 Cleggs, 481 _Cleosiris_, 400 _Cleptes_, 2, 4 Cleridae, 253 Click-beetles, 256 {608} Clicking butterfly, 354 _Clidicus_, 223 _Clisiocampa neustria_, 322 Clothes-moths, 430 Clouded-yellows, 357 Clypeus, 307 _Clythra_ in ants'-nests, 149 Clythrides, _279_ _Cnemidotus caesus_, 209 _Cnethocampa processionea_, 376 Coarctate larva, 271 Coccidae, 592 f.; destroyer of, 290 _Coccidula_, _239_ Coccinellidae, 237 _Coccus cacti_, 598; _C. mannifera_, 597 Cochineal Insect, 598 Cochliopodidae, 402 n. _Cochlophora_, 394 Cockchafer, 198 Cockroach, parasite of, 269 Cock-tail, 225 Cocoon, 46, 55, 66, 109, 122, 328, 347, 373, 376, 384, 385, 391, 403, 404, 405, 407, 419, 424, 436, 460, 462, 494; flax-seed, 460; of ants, 134; aquatic, 280, 377 _Cocytia durvillii_, 382 Cocytiidae, 382 Codling-moth, 428 _Coelioxys_, 31 _Coelonites_, _89_; _C. abbreviatus_, cells of, 89 _Coenomyia ferruginea_, 480 Coenomyiidae, 479 _Coenonympha_, 348 _Colaenis_, _351_ _Coleophora_, 431 Coleoptera, 184 f. _Colletes_, 22; _C. daviesanus_, 30 _Colobopsis_, 138 Colon, 320 Colorado beetle, 278 Colour, corresponding with locale, 201; and surroundings, 337; of larva and habits, 336; of Sphingidae larvae, 381; physiology of larval, 413; of caterpillars and sex, 325; development of, in Hemiptera, 542; of eyes, 440 _Coluocera formicaria_, 240 Colydiidae, 233, 234 _Colydium_, 233 Comb, 63, 64, 65, 78, 79 Combs and brushes, 134 Compound pupa, 452 _Composmyia_, 512 Comstock, on nervures, 317 n. Conchylidae, _427_ Connexivum, 538 Conopidae, 497, _504_ _Conorhinus sanguisuga_, 559 _Copiopteryx_, 373 _Copium clavicorne_, 550 _Copius_, 547 Copper butterflies, 356 Coprides, 195 f. Coprini, _195_ n. _Copris hispanus_, 197 Copulatory pouch, 320, 321 Cordyluridae, _504_ Coreidae, 546 _Corethra_, 467 Corium, 539 _Corixa_, 567 Corixidae, 567 Corn-leaves, larva on, 281 _Coronidia_, 419 _Corotoca_, 227 _Corticaria_, 240 Corylophidae, 228 Corynetides, 253 _Coscinocera hercules_, 372 Cossidae, _369_, 395 Cossonides, 294 _Cossus_, 309; _C. ligniperda_, 319 Costal nervure, 318 Cotton-stainer bug, 548 Cotton-worm, 416 Courtship, 494; of _Hepialus_, 398 f. Coxa, 307 _Crabro_, 129; _C. cephalotes_, 129; _C. stirpicola_, 130 n. Crabronides, 128 f. Crambidae, 425 Crane-flies, 471 _Cratoparis_, 290 Cremaster, 327, 328, 344, 426 Cremastochilini, 200 _Cremastochilus_, 200 _Cremastogaster_, 165, 213; _C. tricolor_, 165 Crepitation, 213, 214 Criocerides, _279_, 280 _Crioceris asparagi_, 281; _C. merdigera_, 281 _Crossocerus_, 130; _C. wesmaeli_, 130 Cryptocephalides, _279_ _Cryptocephalus_, _282_ Cryptocerata, _544_, 562 f. Cryptocerini, 132, 134, 158, 159, 169 _Cryptocerus_, 138; _C. atratus_, 170 Cryptophagidae, 235, _237_ _Cryptophagus dentatus_, 235 Cryptostomes, _279_, 282 _Cteniza ariana_, destroyer of, 490 _Ctenophora_, 475 Ctenostylidae, 517 Ctenuchinae, _409_ Cuckoo-bees, 22 Cuckoo-spit, 577 Cucujidae, _232_, 234 Cucujos, 258 Cuculinae, _20_ _Culex pipiens_, 466 Culicidae, 466 f. Cultelli, 443 Cuneus, 539, 540 {609} Cupesidae, 234 Curculionidae, 290 Curtice, on _Hypoderma_, 516 _Curupira_, 465 Cut-worms, 415 Cyathoceridae, 243 _Cybister laterimarginalis_ or _roeseli_, 210; _C. tripunctatus_, 211 _Cybocephalus_, 232 Cyclica, _279_, 282 Cyclorrhapha, 454; _C. Aschiza_, 455, 494 f.; _C. Schizophora_, 456, 503 f. _Cylidrus_, 253 Cylindrotomina, 474 Cymatophoridae, _368_, 386 Cymbidae, 410 _Cynomyia mortuorum_, 510 _Cyphagogus segnipes_, 296 _Cyphanta_, _368_ n. _Cyphonia clavata_, 576 Cyphonidae, 255 Cyrtidae, 489 Cyrtocorides, 545 _Cyrtocoris monstrosus_, 546

Dacnides, 237 _Dactylopius citri_, 595 Daddy-long-legs, 471 _Dakruma coccidivora_, 424 Dalla Torre, Catalogue of Hymenoptera, 21 Danaides, 344, _347_ Danaioid Heliconiidae, 346 _Danais archippus_, or _plexippus_, 345 Dances, 351, 464, 493, 554 Darwin, C., on _Pelobius_, 208 Darwin, F., on proboscis of Lepidoptera, 311 n. Dascillidae, _243_, 255 _Dascillus cervinus_, 255 _Dasychira pudibunda_, 408; _D. rossii_, 407 Dasygastres, _20_, 35 f. _Dasypoda hirtipes_, 27 Dead-leaf butterfly, 353 Death-watches, 248, 254 December-moth, 406 Deer bot-fly, 517 Deer-fly, 518 Delphacides, _576_ _Deltocephalus inimicus_, 578 Deltoidae, 418, _423_ Denudatae, _20_, 29 _Deporaus_, 291 _Dermatobia noxialis_, 517 Dermestidae, 241 _Deroca_, 400 Derodontidae, 244, _253_ _Derodontus maculatus_, 245 De Saussure, on wasps' nests, 81 Devil's coach-horse, 225 Dewitz, on development, of sting, 8; of thoracic appendages, 9 Dexiidae, 510 _Diactor bilineatus_, 547 _Dianeura_, 392 _Diateina holymenoides_, 547 Dichoptic, 440 _Dicthadia_, 178, 180 _Dictyocicada_, 543 _Dilophus febrilis_, 477; _D. vulgaris_, 476 Dimera, _544_ Dimorphic, generations, 586; males, 161, 172 Dimorphism, 139; of wings, 549 _Dinapate wrightii_, 246 Dingar, 70 _Dinoponera grandis_, 132, 134, 171 _Dionychopus niveus_, 410 Diopsidae, 503, _504_, 505 _Diopsis apicalis_, 503 Dioptinae, 409 _Dioptoma adamsi_, 251 _Dioscorea batatas_, beetle-larvae in, 280 _Dioxys cincta_, 32, 43 Diphyllides, _237_ _Diplocotes_, _248_ _Diplonychus_, 566 _Diploplectron_, 119 Diploptera, _10_, 71 f. _Diplosara lignivora_, 429 _Diplosis_, 459; _D. resinicola_, 459 _Dipsocoris alienus_, 559 Diptera, 438 f. Dipterous parasitic larva, 26 _Dirphia tarquinia_, 377 Discocellular nervures, 318 _Dismorphia_, 346, 357 Dissociation of embryo, 70 n. _Dixa_, 471 Dixidae, 471 Dohrn, Anton, on Hemiptera, 538 _Dolichoderides_, _157_ Dolichopidae, 493 _Dolichopus undulatus_, 441 _Dolichurus haemorrhous_, 116 _Donacia_, 280 Donaciides, 279 Dorsal vessel, 320; 529—see also Internal Anatomy _Dorycera_, 504 Doryceridae, _504_ Dorylides, 174 f. Dorylini, _175_, _177_ _Dorylus_, 133, 177, 179; _D. helvolus_, 178 _Doryphora decemlineata_, 278 Dragon, 383, 385 Drepanidae, _370_, 400 _Drepanosiphum platanoides_, 585 Drepanulidae, 400 Drilides, _248_ Driver ants, 178 Drones, 63, 67, 69 {610} Drosophilidae, _504_ _Drurya_, 362 Dryomyzidae, _504_ _Dryophthorus_, _289_ Dubois, on luminescence, 259 Dudgeon, on _Badamia_, 365 Dufour, on host helping parasite, 26 Duke of Burgundy fritillary, 355 Duration, of ant-colonies, 154; of wasp-colonies, 70 n., 80; of life—see Longevity Durrant, on moth-cases, 431 Dutch bulbs, larva in, 501 Dyar, classification of larvae of moths, 367 _Dycladia_, 389 _Dynastes_, 199 Dynastides, _195_, 199 _Dysdercus suturellus_, 548 Dytiscidae, 210 f. _Dytiscus_, 211

_Earias_, 410 Eau de Javelle, 368 n. _Echinophthirius_, 600 _Eciton_, 159, 175, f; _E. hamatum_, 175, 177 Ecitonini, _174_, 175 f. _Ecpantheria_, 409 _Ectatomma auratum_, 131 _Ectrephes kingi_, 248 Edible larvae, 287 Egg, 305, 435, 468; as food, 504, 568; of bot-fly, 514, 515; of Capsidae, 561; carried, 547, 551, 566; of _Endochus_, 558; of Reduviidae, 559; of flea, 524; laid by pupa, 469; of Lepidoptera, 321, 322; of _Nepa_, 564; numerous, 397, few, 197; standing out string of, 378; swallowed, 508 Egg-tubes, 321 Eggers, 322, 405 _Elaphidion villosum_, 286 _Elaphomyia_, 505 Elateridae, 256 Elaterides, _260_ _Eleodes_, 263 _Elephantomyia_, 472 Elmides, 244 _Elymnias_, 348 Elymniidae, 348 Elytra, 184, 186, 539 Embolium, 539 Embryonic dissociation, 70 n. _Emenadia flabellata_, 269 Emery on classification of ants, 144; on polymorphism in ants, 143 Emesiides, 555 Emperor-moth, 374 Empidae, 492, _494_ Empodium, 446 _Empretia stimulans_, 403 _Encyrtus_, 34; _Encyrtus fuscicollis_, embryology of, 70 Endomychidae, _237_, 239 Endotrichiinae, _423_ Endromidae, _369_, 406 Energopoda, _457_, _491_ _Enhydrus_, 216 Entomophila, _10_ Enzyme, 259 _Epeolus variegatus_, 30 _Ephestia kuhniella_, 306, 424 Ephydridae, _504_ _Ephyra pendularia_, 412 Epiblemidae, _427_ _Epicausis smithi_, 409 _Epichnopteryx_, _395_ Epicopeiidae, _368_, 418 Epicranium, 307 _Epicypta scatophora_, 463 _Epidapus scabiei_, 462 Epilachnides, 238 Epimeron, 307 _Epinotia funebrana_, 428; _E. hypericana_, parasite of, 476 Epipaschiinae, _423_ Epipharyngeal sclerites, 14 Epipharynx, 14, 308, 443, 600 Epiplemidae, _368_, 420 _Epipyrops_, 404 Episternum, 307 _Epitritus_, 170 _Epuraea_, 232 _Erastria scitula_, 417 _Erebia_, _347_; _E. aethiops_, 347 Erebides, 418 Eremochaeta, _457_ Eremochaetous, 446 _Eremocoris_, 548 Ergatandrous, 140 n. Ergatogynous, 140 n., 142 Ergatoid, 140 _Ericerus pela_, 597 _Eriocephala_, 308; _E. calthella_, 434 Eriocephalidae, 433 _Eriocera_, 472 _Eristalis_, 499 Ermine-moths, 409 Erotylidae, _235_, 236 Erucaeformia, 475 _Erycides_, _364_ Erycinidae, _341_, 354, _358_ Erycinides, _355_ _Ethon_, 262 Eucephalous larvae, 450 _Eucera_, _32_ _Eucharis myrmeciae_, 173 _Euchloe cardamines_, egg, 322; larva, 358, 359; pupa, 358; _E. genutia_, 358 _Euchroma goliath_, 261 _Eucinetus_, 256 Eucleidae, 401 _Euclidia mi_, 415 Eucnemides, 260 {611} _Eudaemonia_, 373 _Eudamus proteus_, 340 _Eueides_, 351 _Eugereon hockingi_, 542 _Euglossa_, 34; _E. cordata_, 35 _Eugnoristus monachus_, 289 _Eulema_, 35 Eulen, 414 _Eulyes_, 558 _Eumaeus_, 355 _Eumenes arbustorum_, 73; _E. coarctata_, 73, 74; _E. conica_, 74; _E. flavopicta_, 72; _E. pomiformis_, 72; _E. unguiculata_, 73 Eumenidae, 72 f. Eumolpides, _279_ Eumyiid flies, _456_ _Euparagia_, 89 _Euphoria_, 200 _Euplocia_, 408 _Euploea_, 345 Eupoda, _279_, 280 _Eupsalis minuta_, 296 Eupterotidae, _368_, 376 _Eurygona_, larva, 355 _Euschemon rafflesiae_, 371 _Eusemia vitticoides_, 410 _Eusthenes pratti_, 533 _Euthyrhynchus floridanus_, 546 _Excoecaria biglandulosa_, 424 Excrement as covering, 281, 283, 463—see also Adapted excrement. Excremental dwellings, 284, 379 External structure, of Aphidae, 588; of Chrysididae, 2; of Coleoptera, 185; of Diptera, 439 f.; of fleas, 523; of Hemiptera, 534; of _Hepialus_, 400; of Hymenoptera Aculeata, 5; of Lepidoptera, 307 f.; of Thrips, 527 Exudation of fluid, 238 Eye-collar, 387 Eyes, four in number, 215, 251, 476

Fabre, J. H., on _Ammophila_, 111; on _Anthrax_, 486; on _Bembex_, 120 f.; on _Calicurgus_, 101; on _Chalicodoma_, 37 f.; on _Eumenes_, 72; on _Halictus_, 24; on _Miltogramma_, 509; on _Osmia_, 48 f.; on _Scarabaeus_, 196; on _Scolia_, 97 f.; on _Sitaris_, 272; on _Sphex_, 108; on _Stelis nasuta_, 30 False cones of _Chermes_, 587 Families of moths, key to, 368 f. Feeding young, 147 _Fertonius luteicollis_, 130 Fever-fly, 477 _Filaria_, and Mosquitos, 468 Filicornia, _200_ Finding nest, 38 f., 126 Finn, on protected butterflies, 345 n. Flagella, 384, 442 Flatides, 576 Flax-seed cocoon, 460 Fleas, 522 f. Fly-disease, 513 Food, abstinence from, 254; of bee-larvae, 19; small in amount, 277 Food-reservoir, 320 Footmen, 409 Forbes, on ant sounds, 155 Forel, Aug., on tropical American Ants, 138; on classification of Ants, 144 Forest-fly, 518 _Formica exsectoides_, 149; _F. fusca_, 137, 150, 151; _F. rufa_, 148, 154; _F. sanguinea_, 149; _F. schavfussi_, 152 Formicidae, 131 f. _Formicoxenus nitidulus_, 148, 159 _Fornax_, 260 Fossil, Ants, 143; Beetles, 261; Diptera, 458; Hemiptera, 542; Thrips, 531; Wasps, 88—see also Palaeozoic Fossores, 7, _10_, 90 f., 346; classification, 93 Fossorial solitary wasps—see Fossores Founding new nests, Ants, 145 f. Frenulum, 316, 318, 319, 400 Friederich, on Parnid larvae, 244 Friese, on habits and classification of bees, 21; on hosts and parasites, 30 f. Fritillaries, _352_, 354 Froghoppers, 577 Frog-spit, 577 Frontal ganglion, 320 _Fulgora candelaria_, 575 Fulgoridae, 543, 574; larva living on, 404 Fulgorina, 543 _Fumea_, 393, 395 Fungus cultivated by ants, 167 Fungus-gnats, 462 Funnel-twister, 292

Gad-flies, 481 Gahan, J. C., on _Praogena_, 264 Galea, 309 Galerucides, _279_ Galgulidae, 562 _Galleria mettonella_, 306, 331 Galleriidae, 423 Gall-midge-flies, 461 Galls, 262, 430, 424; of Coccidae, 598; of Aphids and _Phylloxera_, 587; of Psyllidae, 580; of Thrips, 530 Ganglbauer, on Staphylinidae, 224 Garden-whites, 357 Garman, on mouth-parts of Thysanoptera, 528 _Gastropacha quercifolia_, 405 _Gastrophilus equi_, 515 _Gavara_, 401 Gelechiides, 429 Gena, 185 Generations, 306 Geometers, 411 {612} Geometridae, _368_, 411, _416_, _420_ Geomyzidae, _504_ Georyssidae, 243 _Georyssus pygmaeus_, 243 _Geotrupes_, stridulation of, 195 Gerrides, 552 _Gerris_, 535, 552 _Ghilianella filiventris_, 555 Ghost-moths, 396 _Giraffomyia_, 505 Girdlers, 286 Glands, 321, 323, 331, 363, 399, 538, 553; accessory, 320; of Filippi, 324; mandibular, 216; salivary, 326; silk-, 325; stink-, 257; wax-, 589 Glaphyrini, _195_ n. _Glaphyroptera picta_, 441 Glaucopides, 339 Glossa, 309 _Glossina morsitans_, 512, 513 Glow-worms, 248; New Zealand, 363 _Glyptus_, 206 Gnats, 466, 468 _Gnophaela_, 409 Gnostidae, 223 Goat-moths, 395—see also _Cossus_ Godart on trumpeter-bee, 58 Godman and Salvin, on spermathecal bodies, 321 Gold-tail moths, 407 Gonapophyses, 9, 305 Gonin, on development of wing, 328, 329 Goossens, on legs of Lepidoptera larvae, 323 _Gossyparia_, 597 Graber, on mouth of louse, 599 _Grapholitha sebastianiae_, 428 Grapholithidae, _427_ Grass-moths, 425 Grayling, 347 Green, E. E., on classification of Coccidae, 593 Green-bottles, 511 Green-fly, 581 f. Ground-beetles, 204 f. Ground-pearls, 592, 598—see also _Margarodes_ Grypocera, _341_ Guest-ant, 159 Gula, 185 Gymnocerata, _544_, 544 f. Gymnodomes, 82 Gyrinidae, _201_, 215 _Gyrinus_, 215

Haase, on mimicry, 339 n. _Hadrus lepidotus_, 482 _Haematobia serrata_, 512 _Haematomyzus elephantis_, 600 _Haematopota_, 482; _H. pluvialis_, 483, 443 Haemoglobin, 468 _Haemonia_, 280; _H. curtisi_, 280 _Haetera_, 348 Hag-moth, 403 Hairs, plumose or feathered, 11, 12; of Dermestid larvae, 241—see also Setae Half-loopers, 415 _Halias_, 410 _Halictus_, _23_; _H. lineolatus_, 24; _H. malachurus_, 23; _H. maculatus_, 25; _H. morio_, 24; _H. quadricinctus_, 22, 25; _H. rubicundus_, 26; _H. sexcinctus_, 24, 269 Haliplidae, 209 _Halirytus amphibius_, 474 _Halobates_, 552; _H. sobrinus_, 551 _Halobatodes_, 553 Halteres, 438, 448, 593 Halticides, _278_, _279_ _Hamadryas_, 347 Hammock-moth, 379 Hampson, on classification of moths, 367 f.; on clicking butterfly, 354; on frenulum, 316 _Hampsonia pulcherrima_, 391 Handlirsch, on _Bombus_, 58 Harpactorides, 558 Harpalides, _206_ _Harpalus_, 205; _H. caliginosus_, 185 Harpes, 314 Hart, C. A., on larvae of Diptera, 473 Hart, J. H., on the parasol-ant, 142 Harvesting ants, 164 Hatchett Jackson, on colour of larvae, 325 Haustellata, _366_ Haustellum, 308 Hawk-moths, 380 f. Head-vesicle, 442 Hearing, organs of, 191, 313 Heath-butterfly, _347_ Hebridae, 551 _Hebrus_, 551 _Hecatesia_, 371 Heerwurm, 464 Heliconiidae, _346_ Heliconiides, 351 _Heliconius_, 346; _H. erato_, _H. melpomene_, _H. rhea_, 351 _Heliothis armigera_, 416 _Helluodes taprobanae_, 206 _Helochares_, 218 _Helodes_, 255 Helomyzidae, _504_ _Helopeltis_, 561 Helotidae, 235 _Hemaris_, 383 _Hemerodromia_, 493 _Hemidiptera haeckeli_, 553 Hemi-elytra, 539 Hemileucidae, 374 Hemiptera, 532 f. Henicocephalidae, 554 {613} Hepialidae, 306, _369_, 396 f. _Hepialus_, 309, 310, 311, 317, 319, 322; _H. humuli_ and others, 396 f.; _H. lupulinus_, 397 Heredity, 454 _Heriades_, _35_ _Hermatobates haddoni_, 553 _Hermetia_, 479 Hesperiidae, _341_, _342_, 363 Hessian fly, 452, 460 _Hestia idea_, 340 Heterocera, _340_, 366, f. Heteroceridae, _219_, 243 _Heterogenea_, 402 Heterogeneidae, 402 Heterogyna, _10_, 131 f. Heterogynidae, _369_, 392 _Heterogynis_, 369 n., 392 Heteromera, _190_, 262 f. Heteroneuridae, _504_ _Heteronotus trinodosus_, 576 Heteroptera, 532, 534, 535, 539, 543 Heterotarsini, _264_ _Hexatoma pellucens_, 441 Heylaerts, on Psychidae, 392 Hibernation, of _Vanessa_, 352 _Hilara_, 493 _Hilbrides_, 405 Hill-ant, see _Formica rufa_ Hill-grub, 417 Himantopteridae, 392 _Himera pennaria_, 411 _Hippobosca equina_, 518 Hippoboscidae, 518 Hippopsini, 288 _Hirmoneura obscura_, 485 _Hispa_,282 Hispides, _279_, 282 Histeridae, 230 _Histia_, 391 Histoblasts, 453 Histolysis, 452, 595 Hockings, on stingless bees, 63 Hoffer, on _Bombus_, 54 Hollandiidae, 396 _Hololepta_, 230 Holometopa, _504_ Holoptic, 440 Holoptilides, 557 _Holymenia_, 547 Homoeochromatism, 337, 351 _Homoeoderus mellyi_, 193 Homomorpha, 542 Homophysinae, 421 Homoptera, 532, 534, 535, 543, 544; parasite of, 303, 497 Honey, 18, 80 Honey-ant, 152 Honey-bee—see _Apis mellifica_ Honey-dew, 580, 589, 597 Hook-tips, 400 _Hoplopus_, 74 Horn, G. H., on classification of Carabidae, 206; of Silphidae, 223 Horn, W., on classification of Cicindelidae, 202 n. Hornet, 81, 87 Hornet's-nest beetle, 227 Horns as food, 430 Horse bot-fly, 515 Horse-flies, 481, 518 Hot springs, Insects in, 479 House-fly, 511 Hover-flies, 498 Hubbard, on ambrosia-beetles, 295; on _Phobetron_, 403; on _Xenos_, 303 Huxley, on Aphids, 585, 589; on sclerites of oesophagus, 15 _Hybocampa milhauseri_, 385 Hybotinae, 492 _Hydnophytum_, 139; _H. montanum_, 138 _Hydrocampa nymphaeata_, 421 Hydrocampidae, _42l_ Hydrocampinae, 421 Hydrocores, 562 Hydrocorisae, 562 _Hydrocyphon deflexicollis_, 255 _Hydrometra_, _552_; _H. stagnorum_, 551 Hydrometridae, 551 Hydrophilidae, 216 f. Hydrophilides, _219_ _Hydrophilus piceus_, 217 Hydroporides, 201 _Hydroporus_, 211, 212 Hydroscaphidae, 228 _Hydrous caraboides_, 218 _Hygrobia_, 208 _Hylecoetus dermestoides_, 255 _Hylemyia strigosa_, 506 _Hymenitis_, 346 Hymenoptera Aculeate, 4 f.; H. Tubulifera, 1 f. Hyper-metamorphosis, 270, 488 Hypertely, in _Kallima_, 354 _Hyphydrus_, 212 Hypnody, 489 _Hypocephalus armatus_, 288 Hypochlorite of potash, 368 n. _Hypoderma bovis_, _H. lineata_, 515 _Hyponomeuta_, parasite of, 70 n. Hypopharyngeal sclerites, 14, 17 Hypopharynx, 15 n., 324, 443, 524, 600 Hypopygium, 446 Hypsidae, _370_, 408 _Hypsoides radama_, 376 _Hystrichopsylla talpae_, 523

_Idia fasciata_, 513 _Idolothrips spectrum_, 527 Imaginal discs or folds, 596 Imbauba ant, 158 Individual, 585 Inedible associations, 338, 339 Infericornia, 548 {614} Infra-oesophageal ganglion, 541 Inquilines, 30, 81 Insects as food, 417, 504, 568 Instars, of _Aspidiotus_, 596; of Coccidae, 595; of _Epicauta_, 271 Instinct, 235, 274, 373, 403, 424, 487, 546; of Ants, 590; of _Bembex_, 121; of _Chalicodoma_, 37; of _Dasypoda_, 28; of _Melipona_, 64; of _Miltogramma_ and _Bembex_, 509; of _Odynerus_, 76; of _Osmia_, 48 f.; of _Pompilus_, 102; of _Rhynchites_, 292; of _Trigona_, 64 Internal anatomy, of Diptera, 449; of _Hepialus_, 400; of Hemiptera, 540; of Lepidoptera, 319 f.; of larva of Lepidoptera, 324; of Lice, 600 Internal nervures, 318 Iodine, 213 Ipides, 232 Ischium, 523 _Ischnogaster_, 82, 88; _I. mellyi_, 87 Isoderminae, 550 Isomera, _190_ Issides, _576_ _Ithomia_, 346; _I. pusio_, 346 Ithomiides, 346, 351 _Ituna_, _346_ _Ityraea nigrocincta_, 576

Jassidae, 578 Jiga, or "mimic me," 92 Johnston's organ, 442 Jordan, on antennae of butterflies, 341 n.; on Thysanoptera, 529 f. Jugatae, _366_ Jugum, 316, 400 _Jugurthia_, _89_ _Julodis_, 262 Jumping-beans, 428

_Kallima_, 353 Karbi, 63 Kellogg, on Lepidopterous structure, 307 f. Kentish glory, 406 _Kermes_, 597 Knot-horns, 424 _Komarovia victoriosa_, 99 Koo-chah-bee, 504 Kootchar, 63 _Koptorthosoma_, 70 n. Korschelt, on formation of eggs of _Nepa_, 564 Künckel d'Herculais, on _Volucella_, 501 Kungu cake, 467

Laap Insects, 581 Labella, 443 _Labidus_, _175_, 176, 180 Labium of Lepidoptera, 310 Laboulbène, on sound-production by Arctiidae, 410 Lac, 597 Lacinia, 309 Laciniata, _366_, 434 _Lacon murinus_, 257 _Lacosoma chiridota_, 378 Lady-birds, 237 _Lagoa opercularis_, 404 Lagoidae, 404 _Lagria hirta_, 264 Lagriidae, 264 Lake, colour, 597 Lamellicornia, _190_ f.; enemies of, 97 Lamiides, _287_, 288 Lamprosomides, _279_ Lampyrides, 248 _Lampyris noctiluca_, 250 _Langelandia anophthalma_, 233 Languriides, 237 Lantern-flies, 575 Laparosticti, _195_ n. _Laphria_, 492 Lapidicolous beetles, 205 Lappet-moth, 405 _Laricobius_, 253 _Larra anathema_, 117; _L. pompiliformis_, 117 _Larrada_, 117; _L. modesta_, 118 Larrides, 116 f. Larvae, of beetles, 188 f., 188; of _Chrysis_, 3; of _Dasypoda_, 28; of Hymenoptera, 7; of Lepidoptera, 323; of _Sphex_, 109 Lasiocampidae, _369_, 375, 405 _Lasiorhynchus barbicornis_, 297 _Lasius alienus_, 140; founding nest, 146; _L. fuliginosus_, 138, 153; _L. niger_, 153 Latridiidae, 240 _Latridius minutus_, 240 Latter, O., on Puss-moth, 384 Leaf-cutting ants, 165 f. Leaf-nests (ants), 155 _Lecanium hesperidum_, 594; _L. oleae_, 417; _L. persicae_, 597 _Ledra_, 545, _578_ Legs, abdominal, 9 _Leistus spinibarbis_, 204 _Lema melanopa_, 281 Lemoniidae, 354 Léon, on _Hemidiptera_, 553 Lepidoptera, 304 f.; L. Haustellata, L. Laciniata, _366_ _Leptalis_, 346, 357 Leptidae, 479 Leptinidae, 220 _Leptinillus_, 221 _Leptinus testaceus_, 220 _Leptis scolopacea_, 441, 481 _Leptocircus_, 362 Leptoderini, 221 _Leptogenys_, 171; _L. falcigera_, 171 _Leptomastax_, 223 _Leptothorax acervorum_, 161 Lerp Insects, 581 _Leto_, 397; {615} _L. venus_, 396 _Leucania unipunctata_, 416 Leuckart, on _Melophagus_, 519 _Leucospis_, 46; _L. gigas_, 44 Leuthner, on _Odontolabis_, 193 _Libythea_, _342_ Libytheides, 355 Lice, 599 f. Ligula, 16 _Limacodes_, 489 Limacodidae _370_, 401; parasite of, 4 _Limnas chrysippus_, 345 Limnichides, 242 _Limnobia intermedia_, 472 Limnobiinae, 472 _Limochores taumas_, 340 _Limothrips denticornis_, 530 Lindeman, on injuries from Thrips, 530 Lingua, 16 Lingula, 15 _Liometopum microcephalum_, 158 _Lipara lucens_, 128, 451 Liparidae, 406 _Liponeura brevirostris_, 465 Liponeuridae, 464 _Lipoptena cervi_, 518 _Liptena_, 356 Lipteninae, 356 _Lita solanella_, 430 _Lithophilus_, 239 Lithosiidae, 408 Lithosiinae, 409 _Llaveia axinus_, 598 Lobster, 383; Lobster-moth, 385 _Loepa newara_, 374 _Lohita grandis_, 549 _Lomaptera_, 200 _Lomechusa_, 142, 225 Lonchaeidae, _504_ Lonchopteridae, 490 Longevity, 33, 135, 286, 306; of _Cicada_, 569; of _Melolontha_, 198; of _Scarabaeus_, 197 Longicorns, 285 Loopers, 411, 415 Lorum, 14, 14, 16 Lowne, on blow-fly, 449; on foot of _Dytiscus_, 211 Lucanidae, 193 _Lucanus cervus_, 194; antenna of, 191 Luciferase, Luciferine, 259 _Lucilia_, 511, 512; _L. caesar_, _L. macellaria_, _L. sericata_, 512 _Luciola_, 249; _L. italica_, 249 _Ludia delegorguei_, 373 Luminescence, 250, 258 f., 463, 469 Lunula, 442 Lutz, on exudation of Coccinellidae, 238 _Lycaena baetica_, 356 Lycaenidae, _341_, _355_, 356 Lycides, _248_ _Lycorea_, 346 Lyctides, _246_ Lygaeidae, 548 Lymantriidae, _370_, 406 _Lymexylon navale_, 254 Lymexylonidae, 254 Lyonnet, on anatomy of caterpillar, 324 n.

_Machaerota guttigera_, 578 M‘Cook, on honey-tub ants, 152 _Macrocneme_, 389 Macroglossini, 380 Macrolepidoptera, 340 _Macronychus quadrituberculatus_, 244 _Macrotoma heros_, 287 Maggot, 449 Malachiidae, 252 _Malachius aeneus_, 252 Malacodermidae, 248, _252_, 266 Malaxation, 110, 126 Malpighian tubes, 320, 334, 429, 449, 460, 466, 473, 529, 540, 588 _Mamillo curtisea_, 378 Man—see Manna Mandibles, of Lepidoptera, 308; of pupa, 436, 437 Mandibulata, 434, 536 Manna, 597 Manson, on Mosquitoes, 468 _Manticora maxillosa_, 203; _M. tuberculata_, 202 _Marane_, 377 Marbled-white, _347_ Marchal, on embryonic dissociation, 70 n.; on _Ammophila_, 111; on pigments, 334 _Margarodes_, 595, 597, 598; _M. vitis_, 598 Marimbouda da casa, 118 _Maruina_, 471 Masaridae, 88 f. _Masaris_, 89; _M. vespiformis_, 88, 89 Mason-bee, 35 f.—see _Chalicodoma_; of New Zealand, 107 _Mastigus_, 223 Matthews, on Hydroscaphidae and Corylophidae, 228; on Sphaeriidae, 227 Maxillae, of Lepidoptera, 309 Mayer, Paul, on Hemiptera, 536 Meadow-brown, _347_ Meal-worm, 263, 264 Mealy-bugs, 592 Mechanitidae, _346_ _Medeterus ambiguus_, 493 Median nervure, 318 _Megacephala_, 201 _Megachile_, _35_, 51; _M. albocincta_, 52, 53; _M. anthracina_, 52; _M. fasciculata_, 52; _M. lanata_, 53; _M. proxima_, 53 Megalopides, _279_, 282 Megalopygidae, 404 _Megalybus gracilis_, 490 _Meganostoma_, 543 _Megarrhina_, 445, 467 Megascelides, _279 Megasoma_, 199 {616} _Megathymus_, 371 _Megistorhynchus longirostris_, 485 Meijere, on stigmata, 450 Meinert, on Anoplura, 600; on mouth of Diptera, 444; on paedogenesis, 461; on _Stylops_, 302 Melandryidae, 265 Melanism, 414 _Melanitis_, 351 _Melanophila decostigma_, 261 _Melecta_, 31, 33; _M. luctuosa_, 31 _Meliboeus_, larva, 355 _Meligethes_, 232 _Melinaea_, 351 _Melipona_, _53_, 62; _M. scutellaris_, 64 _Melitaea_, larvae, 354 Mellifera, 10 _Mellinus_, 123; _M. arvenis_, 123, 124; _M. sabulosus_, 124 _Meloe_, 33, 274 Meloidae, 269 Meloides, _270_ _Melolontha vulgaris_, 194, 198 Melolonthides, _195_, 198 _Melophagus ovinus_, 518, 519 _Melophorus inflatus_, 153 Melyridae, 252 Membracidae, 576, _578_ _Membracis foliata_, 577 n. Membrane, of Hemiptera, 539 Menorhynchous, 542 _Merodon equestris_, 501 Merrifield, temperature experiments, 337 Mesodont, 193 Mesophragma, 312, 445 Mesoscutellum, 312 Mesoscutum, 311 Mesosternum, 307 _Mesovelia_, 551 Mesozoic beetles, 261 _Messor_, 164 _Metamorpha_, _351_ Metamorphosis, 529; of Aleurodidae, 591; of _Cicada_, 571; of Coccidae, 594 f.; of Diptera, 452; of Hemiptera, 542 Metapneustic, 450 Metascutellum, 313 _Methoca ichneumonides_, 96 Metochy, 183 _Metoecus paradoxus_, 268 Meyrick, classification of Lepidoptera, 367 _Miastor_, 461 Mice, insects in nests of, 221 _Microdon_, 501, 502 Microlepidoptera, _340_, 427; trophi, 309 Micropezidae, 504 Microphysides, 560 Microptera, _224_ Micropterism, 549 Micropterygidae, _369_, 435 _Micropteryx_, 307 f., 317, 319, 327, _433_, 435, 436 Midge, 461, 470 Migration, Aphis-, 585 Mik, on _Hilara_, 493 Milichiidae, _504_ _Miltogramma_, 121, 508 _Mimacraea_, 356 _Mimesa bicolor_, 128 Mimesides, 127 Mimicry, 337 f.—see also Resemblance Mines, Dipteron in, 474 _Miscophus_, 116 Models, 346 Moesa-blight, 561, 562 Mollusca, eaten by beetle-larvae, 252; larvae mistaken for, 501—see also Snails _Molossus_, parasite of, 560 Monarch-butterfly, 345 _Monda rhabdophora_, 393 _Monema flavescens_, 4 Moniez, on fertilisation of Coccidae, 594 _Monodontomerus nitidus_, 44 _Monohammus confusus_, 286 Monomera, _544_ Monommidae, 265 _Monomorium_, 560; _M. pharaonis_, 163 Monotomides, 240 _Montezumia dimidiata_, nest of, 83 _Mordella_, 268 Mordellidae, 267 _Mordellistena floridensis_, 268 _Mormolyce_, 205 Mormolycides, _206_ Morphides, 348 _Morpho_, 315, 331, 349; _M. menelaus_, 318; _M. achilles_, _M. epistrophis_, larvae of, 349 Mosquito, 466 f. Mosquito-bees, 61 Mosquito-blight, 562 Moth-flies, 470 Moths, 366 f. Motuca fly, 122, 482 Mouth, absence of, 310, 443, 489, 514, 515, 585, 596 Mouth-parts, of Diptera, 442 f.; of fleas, 523; of Hemiptera, 534, 535; of Hymenoptera Aculeata, 13; of Lepidoptera, 307 f.; of Lice, 599, 600 Mud-dauber, 113 Müggenburg, on _Melophagus_, 518 Müller, Fritz, on Imbauba-ant, 158; on _Trigona_, 64 Müller, H., on _Dasypoda hirtipes_, 27 Müller, W., on South American larvae, 344 n. Müllerian mimicry, 339 Mundstachel, 527, 528 Murray, A., on Lice, 601 _Musca domestica_, 511 Muscidae, 511 f., 517; M. Acalyptratae, 503 f.; M. Calyptratae, 448, 504 Musotimidae, 423 {617} Mustiliidae, _376_ _Mutilla_, 94, 95; _M. europaea_, 94 Mutillides, 94 f. _Mycetaea hirta_, _239_, 240 Mycetaeidae, 239 _Mycetobia pallipes_, 462, 463 Mycetophagidae, 237 Mycetophilidae, 462 Mydaidae, 491 _Mygnimia_, 105 Myiasis, 512 _Myiatropa florea_, 499 _Myiodocha tipulina_, 557 Myoditini, 267 Myopinae, 497, 498 _Myrapetra_, 82 _Myrmecia_, _171_, 172, 173 _Myrmecocystus hortideorum_, 152; _M. melliger_, 152; _M. mexicanus_, 152 _Myrmecodia_, 139 Myrmecophilous Insects, 181 f. _Myrmedonia_, 226 _Myrmica laevinodis_, 148; _M. rubra_, 133; _M. rubra_, races _ruginodis_, _scabrinodis_, 163 _Myrmicides_, 158 Myrmicini, 159

Nabides, 556 _Nabis lativentris_, 556 _Nacerdes melanura_, 266 _Naclia ancilla_, 390 Nagana, 513 Nagel, on digestion by injection, 212 _Nagoda nigricans_, 401 _Nanosella fungi_, 228 Nassonoff, on Strepsiptera, 301 n., 302 Naucoridae, 565 _Necrobia ruficollis_, 253 _Necrophorus_, 221 Nectar, 18 _Neleus interruptus_, antenna, 191 _Nematobola orthotricha_, 431 Nematodes, in Thysanoptera, 530 _Nematois metallicus_, 321 Nemeobiides, 355 _Nemeobius lucina_, 335, 355 _Nemestrina_, 455 n. Nemestrinidae, 484 Nemocera, 440; N. Anomala, N. Vera, 456 _Nemognatha_, 304 Nemosomides, _233_ Neocastniidae, 372 Neolepidoptera, 366 Neotropidae, _346_ _Nepa_, 541; _N. cinerea_, 563 Nepidae, _544_, 563 _Nepticula_, 431 Nervous system, Coleoptera, 191 Nervules, 319, 429 Nervuration, of Diptera, 447; of Lepidoptera, 317 f. Nervures, 318, 319; development of, 329 f.; swollen, 347, 348; of _Eumenes_, 73 Nests, of ants, 136 f., 155; of _Formica fusca_ and _Solenopsis fugax_, 137; of _Porphyraspis_, 284; of wasps, 79 f., 79, 81, 83, 87 Netrocera, _341_ n. Neuroblasts, 453 Newbigin, Miss, on pigments, 334 Newport, on _Meloe_, 270 Nicagini, _195_ Nicolas, on _Halictus_, 24 Nilionidae, 265 _Nitidula_, 232 Nitidulidae, 231, _235_ Noctuidae, 311, _370_, _410_, 411, 414 f. Node, 131, 134 Nolidae, 410 Nolinae, 409 _Nomada_, 30; _N. lathburiana_, 30; _N. sexfasciata_, 30 Nonne, 407 Nopal cactus, 598 Nosodendrides, _242_ _Notocyrtus_, 558 Notodontidae, 305, _368_, 383 Notodontina, _411_ Notonectidae, 567 Number of species: of Apidae, 10; of Butterflies, 343; of Coccidae, 593; of Coleoptera, 184; of Diptera, 438; of Fleas, 525; of Hemiptera, 543; of Lepidoptera, 306; of Lice, 600; of Thrips, 527 Nun, 407 Nurses, 66, 134 _Nyctalemon_, 419 Nyctemeridae, 409 Nycteolinae, 410 _Nycteribia_, 521, 522 Nycteribiidae, 521 Nymph, of _Cicada_, 569; of Thrips, 529 Nympha inclusa, 452 Nymphalidae, 341, 343 f. Nymphalides, 351 Nymphipara, 518 _Nymphula stagnata_, _N. stratiotata_, 423 _Nyssonides_, 123

Oak-Pruner, 286 Obtusilingues, _20_ Oceanic bugs, 552 Ocelli, 325; O. compositi, 325 Ochthiphilidae, _504_ _Ocneria_, 407 n.; _O. dispar_, 408 _Ocnerodes_, 489 _Ocnogyna_, 409 _Ocypus olens_, 225 _Odontolabis sinensis_, 193 Odontomachi, _171_, 173 Odour, of bugs, 541 _Odynerus_, 74 f., 269; {618} _O. antilope_, 75; _O. callosus_, 76; _O. parietum_, 3; _O. punctum_, 77; _O. reniformis_, 73, 75; _O. spinipes_, 3, 76 _Oecocecis guyonella_, 430 _Oecodoma_, 137, 164, 165; _Oe. cephalotes_, 133 _Oecophylla smaragdina_, 147 Oecophoridae, 429 Oedeagus, 314 [recte aedeagus] _Oedematopoda princeps_, 387 Oedemeridae, 266 Oestridae, 514 _Oestrus ovis_, 517 _Ogcodes_, 489, 490 Oil-beetles, 269 _Oinophila v-flavum_, 430 Olethreutidae, _427_ _Olibrus bicolor_, 231 _Oligarces_, 461 Oligonephrous, 542 Oligoneura, 461 Ommatophorinae, 414 _Oncideres_, 286 _Opetia_, 496 _Ophideres fullonica_, 311 Opomyzidae, _504_ _Opostega_, 429 Orange-tip, 357—see also _Euchloe_ _Orectochilus_, 216 _Oreta hyalodisca_, 400 Origin of parasitic bees, 32 Orneodidae, _340_, _371_, 426 _Ornithoptera_, 360; _O. brookiana_, 362; _O. paradisea_, 360, 361, 362 Orphnephilidae, 470 Ortalidae, _504_, _506_ _Ortalis_, 447 _Orthezia_, 541, 598 Orthogenya, _494_ _Orthogonius_, 206 _Orthoperus atomarius_, _O. brunnipes_, 228 Orthoptera, _533_; parasite of, 497 Orthorrhapha, 454; O. Brachycera, 478 f.; O. Nemocera, 455, 458 f. _Oryctes nasicornis_, 199 Oscinidae, _504_ Osmeterium, 363 _Osmia_, 47, 48 f; enemy of, 100; hair of, 11; _O. cyanoxantha_, 32; _O. leucomelana_, 29; _O. tricornis_, 48; _O. tridentata_, 48 f. Osten Sacken on Bugonia, 499; on Chaetotaxy, 446; on classification of Diptera, 456; summary of Portschinsky, 512 Othniidae, 265 Otiorhynchides, 437 _Ourocnemis_, 355, _356_ Ovaries, 541, 602; in larva, 325 Oviduct, 320, 321 Oviposition, of _Cicada_, 571; of _Notonecta_, 567; of _Tachina_, 507 Ovipositor, 436, 506, 531, 539 Owlet-moths, 414 Ox-warbles, 517 _Oxybelus_, 129 Oxychirotinae, 425 Ozaenides, 214

_Pachypus_, 187 Packard, on Hymenopterous metamorphosis, 7 Pad, of Lepidoptera, 314 Paedogenesis, 303, 461 Pagiopoda, _544_ Palaeolepidoptera, _366_ _Palaeomicra_, 435 Palaeotropinae, _347_ Palaeozoic Insects, 311, 542 Palmer-worm, 323 Palpicornia, _219_ _Paltostoma_, 465 _Palustra_, 377 _Pangonia longirostris_, 482 _Panomoea_, 237 Panurgides, _20_ _Papilio_, 359; _P. ajax_, forms of, 335; _P. antimachus_, 362; _P. zalmoxis_, 362 Papilionidae, _342_, _357_, 359 _Paracelyphus_, 505 _Paragia_, _89_ Parallel series in Aphidae, 585 _Parandra_, 288 _Parapompilus gravesii_, 105 _Paraponera clavata_, 172 _Paraponyx_, 423 Paraptera, 312 Parasites, among ants, 183; of mason-bee, 43; of larva of _Andrena_, 26; of _Odynerus_, 76 Parasitic, bees, 23, 29 f.; _Prosopis_, 32; Diptera, 507 _Parasyscia_, _175_ n. _Parmula_, 501 _Parnassius_, _342_, 362 Parnidae, _219_, 243, _255_ _Parnopes carnea_, 4 _Parnus_, 244 Parthenogenesis, 24, 85, 86, 395, 430, 469, 530, 583, 594 Parthenogenetic young, 139 n. Passalidae, 192; larva, 192, _262_ _Passaloecus_, 128 Patagia, 311, 312 Pattern, formation of, 335 _Patula_, 414 Paurometabola, 542 Paussidae, _201_, 213 _Paussus cephalotes_, etc., 214 _Pavonia_, 350 Pea-weevil, 277 Peacock butterfly, _352_ Peal, on sound-producing ant, 156 Peckham, on Fossores, 130 n.; on instinct, 70, 99 _Pectinicornia_, _194_ {619} _Pedicinus_, 600 Pediculidae, 599 _Pediculus capitis_, 599, 601; _P. melittae_, 274; _P. vestimenti_, 601 Pedilidae, _266_ Peduncle, 133, 134 _Pegomyia inanis_, 79 Pelobiidae, 207 _Pelobius tardus_, 208 Pelogonidae, 562 _Pelopaeus_, 110, 112 n.; _P. bilineatus_, 114; _P. laetus_, 113, 117; _P. madraspatanus_, 113; _P. spirifex_, 112 _Peltasticta_, 245 Peltides, 233 _Pemphigus_, 589 _Pemphredon lugubris_, 128 Pemphredonides, 127 Penis, 314 Pentamera, _190_ Pentanephria, 466 _Pentatoma_, 541; _P. rufipes_, 535 Pentatomidae, 533, 545, _546_ _Pepsis_, 104, 389; _P. formosus_, 105 Pérez, on bee-parasitism, 32; on _Halictus_, 24 _Pericoma canescens_, 470 Pericopinae, 409 _Peridrepana_, 401 _Perilitus_, 282 Peripneustic, 450 Peritracheal spaces, 332, 333 Perkins, R. C. L., on bee and acarid symbiosis, 70; on _Odynerus_, 76; on _Prosopis_, 21 _Perophora batesi_, _P. melsheimeri_, 377; _P. sanguinolenta_, 379 Perophoridae, 377 Perothopides, 260 Peytoureau, on morphology of abdomen, 313, 314 Phaeism, 337 Phalacridae, 231 _Phalacrocera replicata_, 474 Phaloniadae, _427_ _Phanaeus splendidulus_, antenna of, 191 Pharynx, 320 Phaudinae, 392 _Pheidole_, 165 _Pheidologeton laboriosus_, 159; _P. diversus_, 167 _Phenax_, 575 _Phengodes hieronymi_, 249 Phengodini, 251 _Philaenus spumarius_, 577 Philanthides, 124 f. _Philanthus apivorus_, 127; _P. triangulum_, 125 _Phileurus didymus_, antenna, 191 _Philonthus nitidus_, 225 _Phlebotomus_, 470 _Phloea corticata_, 545 Phloeides, 545 _Phloeothrips frumentarius_, 530 _Phobetron pithecium_, 403 _Phonapate_, 246 Phoridae, 494 _Phosphaenus hemipterus_, 249 Phosphorescence, 250—see also Luminescence Phragma, 307, 313 Phragmocyttares, 81 _Phthanocoris_, 543 Phthiriasis, 601 _Phthirius inguinalis_, 601 Phycitidae, 424 Phycodromidae, _504_ _Phyllocnistis_, 431 _Phyllomorpha laciniata_, 547, 548 _Phyllorhina_, parasite of, 520 _Phylloxera_, 587 Phylogeny of butterflies, 343 n. Phymatidae, 554 _Phymatopus_, 399 Physapoda or Physopoda, 531 Phytomyzidae, _504_ Phytophaga, _190_, _237_, 276 f. _Phytophthires_, _544_ Phytoscopic effects, 336 _Pierella_, 348 Pieridae, _341_, 357 _Pieris brassicae_, 340; development of wing, 328, 329, 333 _Piesma_, 550 Pigments, 330, 334, 357 Pilifer, 308 Pill-beetles, 242 Pinaridae, 405 Piophilidae, _504_ Pipunculidae, 496 _Pipunculus_, 496 _Pison_, 118 Pit-falls, 481 _Plagiolepis trimeni_, 153 _Plagithmysus_, 287 Plant-lice, 581 f. Plants and ants, 183 Plataspides, 545 _Platycnema_, 496 Platypezidae, 496 _Platyphora lubbocki_, 495 Platypides, 289, 295 Platypsyllidae, 219 _Platypsyllus castoris_, 219 _Platysoma depressum_, 230 Platystomidae, _504_ _Plea minutissima_, 567 Pliny, on Mason-bee, 44 _Ploiaria pallida_, 556 Plume-moths, 426 Plumules, 331 _Plusia_, 415 _Pochazia_, 576 Podilegidae, _32 Poecilocampa populi_, 406 {620} _Poecilocapsus lineatus_, 542 Poecilocyttares, 81 _Pogonomyrmex barbatus_, 164 _Pogonostoma_, 203 Poison, of Hymenoptera, 7 f. Poison-glands, 2 Poisonous caterpillars, 376, 403, 404, 405 _Polistes_, 86; _P._ and _Stylops_, 301, _303_ Pollen-gathering and -carrying, 11, 12 _Polybia_, nests of, 81, 82, 83 _Polyctenes fumarius_, 560 Polyctenidae, 560 _Polyergus lucidus_, 151; _P. rufescens_, 150 f. Polymorpha (Coleoptera), _189_, _190_, 213 f. Polymorphism, 139 f., 143 _Polyphylla fullo_, antenna, 191 _Polyploca_, 386 Polyplocidae, 386 _Polyplocotes_, _248_ _Polyrhachis_, 155; _P. pandurus_, 156; _P. spinigera_, 138 Pompilidae, 93, 101 f. _Pompilus_, 103; _P. polistoides_, 104; _P. sericeus_, 106 _Ponera contracta_, _P. ergatandria_, _P. punctatissima_, 172 Ponerides, 132, 170 f. _Porphyraspis tristis_, 284 _Porphyrophora polonica_, 597 _Porrorhynchus_, 216 Portschinsky, on habits and development of Muscidae, 507, 512 Post-metamorphic growth, 141 Post-scutellum, 307, 312 _Potamogeton pectinatus_, beetle on, 280 _Potamophilus acuminatus_, 244 Potassium hydroxide, 328, 384 Potato-beetle, 278 Pouch, abdominal, 350, 362 Poulton, on colours, 336, 339 Praecostal nervures, 319 Praescutum, 312 Pratt, on imaginal discs, 453 n.; on _Melophagus_, 519 _Prepona_, larva, 354 Prey, of Fossores, table, 92 _Pria dulcamarae_, 232 Primitive, beetles, 251, 252; Diptera, 475 _Priocnemis affinis_, 5; _P. bicolor_, 107 Priodont, 193 Prionides, 287 Proboscis, 13, 14, 16, 17, 304, 307, 309, 311, 443, 482, 485, 532 Processional maggots, 464 Processionary caterpillars, 376, 408 Prodoxidae, 432; mouth, 309 _Prodoxus_, 433 Pro-legs, 323 Prolific, Aphids, 589; Coccids, 594; _Hepialus_, 397; Lice, 601; _Meloe_, 274; _Stylops_, 301 Prominents, 383 _Pronuba_, 321; _P. yuccasella_, 432; _P. synthetica_, 432 Pronymph, 453 Propodeum, 131, 133 Propolis, 63 Propygidium, 187 _Prosopis_, _21_, 22; hair of, 11; proboscis of, 17; _P. signata_, 21 Protection, 43, 413; of trees by ants, 158; of plant by ants, 168 Proterhinidae, 298 _Proterhinus lecontei_, 298 Protolepidoptera, _336_ _Protoparce carolina_, 309 _Protopaussus_, 214 _Psammorycter vermileo_, 481 Pselaphidae, 223; and ants, 182 _Psen atratus_, _P. concolor_, 127 _Psephenus_, 244 Pseudholoptic, 440 n. Pseudocorylophidae, 228 _Pseudodicthadia_, 180; _P. incerta_, 177 _Pseudodoxia limulus_, 431 _Pseudomeria graeca_, 99 Pseudomorphides, 205, _206_ _Pseudomyrma bicolor_, 168 Pseudomyrmini, 168 Pseudoneuroptera, _527_ Pseudopaedogenesis, 303 Pseudopod, 188, 264, 267, 290, 449, 492 _Pseudopontia paradoxa_, 357 Pseudo-pupa, 271, 273 Pseudotetramera, _190_ Pseudotrimera, _239_ _Pseudovespa_, 88 Pseudovarium and Pseudovum, 584 Pseudovitellus, 588 Psilidae, _504_ _Psiliglossa_, larva, 8 _Psilocephala_, 484 _Psilura monacha_, 407 _Psithyrus_, _53_, 57, 59 f.; _P. campestris_, 60; _P. vestalis_, 60 Psocidae, 248 _Psyche helix_, 394 Psychidae, _369_, 392 Psychina, _394_, _395_, 404 _Psychoda_, 466 Psychodidae, 470 _Psylla pyricola_, 579, 580; _P. succincta_, 579; _P. buxi_, 580 Psyllidae, 578 _Pterocheilus_, 76 _Pterodecta_, 400 Pterophoridae, _340_, _371_, _425_, 426 Pterophorinae, 426 _Pterostichus_, 205 Pterothysanidae, _369_, 406 Pterygodes, 312 Pterygogenea, 542 Ptilinum, 442, 503, 520 _Ptilinus pectinicornis_, 253 {621} _Ptilocnemus sidnicus_, 557 _Ptilomacra_, 395 _Ptilomera laticaudata_, 553 Ptinidae, 246 _Ptomaphila lacrymosa_, 222 _Ptychoptera_, 466 Ptychopterinae, 472 _Ptyelus goudoti_, 577 Pugs, 411 _Pulex avium_, _P. irritans_, _P. serraticeps_, 525; _P. obtusiceps_, 525 Pulicidae, 522 f. _Puliciphora lucifera_, 495 Pulvillus, 446 Pupa, of beetles, 188 f.; coarctata, 452; obtecta, 227, 327, 451; depositing eggs, 469; hairy, 407, 426; of Lepidoptera, 326 f.; with mandibles, 436 Puparium, 452 Pupation, of _Badamia_, 365; of _Parnassius_ and _Thais_, 363 Pupipara, 456, 513, 517 Purple emperor, 344 Pusci, 504 Puss-moth, 328, 383, 406 Pygidium, 187 Pyralidae, _340_, _370_, 420 _Pyralidina_, _420_, _426_ _Pyrameis atalanta_, 353; _P. cardui_, 353; _P. tameamea_, 353 Pyraustidae, 421 _Pyrochroa rubens_, 266 Pyrochroidae, 266 _Pyrophorus_, 258; _P. noctilucus_, 259 Pyrrhocoridae, 549 _Pyrrhocoris apterus_, 535, 549 _Pyrrhopyge_, 364 Pythidae, 265 _Pytho depressus_, 266

_Quartenia_, _89_ Queen, 66, 67, 69, 140

Races, of _Apis_, 68 Radial nervures, 319 Raffray, on _Pogonostoma_, 204; on classification of Paussidae, 214; on classification of Pselaphidae, 224 Railway-beetle, 251 _Ranatra linearis_, 563 Raptorial legs, 493, 554, 556 Réaumur, on _Xylocopa_, 33 Receptaculum seminis, 140 Rectal cauda, 538 Red admiral, _352_ Red ant—see _Formica rufa_ Reduviidae, 555 f. 537 _Reduvius personatus_, 558 Régimbart, on Gyrinidae, 216 Resemblance, between ant, wasp, and spider, 169; between _Anthophora_ and _Bombus_, 33; between _Arctia villica_ and _Eusemia villicoides_, 410; between beetle-larva and Termite, 206; between _Bombus_ and _Eulema_, 35; between Bombyliidae and Hymenoptera, 489; between bug and ant, 556, 557; bug and Tipulid, 556, 558; bug and fly, 547; in butterflies, 348; between Callidulidae and Lycaenidae, 400; between _Celyphus_ and Hemiptera, 505; between Cleridae and insects they destroy, 254; between Dioptinae and Ithomiides, 409; between Diptera and Hymenoptera, 499, 500; between _Epicopeia_ and _Papilio_, 418; between Flatides and Lepidoptera, 576; of flies and bees, 502; to galls, 403; between host and parasite-bees, 30; between Insects of different Orders, 339; of Ithomiides to other butterflies, 346; between lady-bird and Endomychid, 237; of larva to a colony of larvae, 418; of larva of _Odynerus_ and of _Chrysis_, 4; between larvae, 162; in Limacodidae, 401; of Lobster caterpillar, 385; between Longicorns and Hymenoptera, 287; of moth to bird-excrement, 401; of parasite and prey, 95; of Pericopinae and Heliconiides, 409; between protected butterflies, 345; between _Psithyrus_ and _Bombus_, 59; of Reduviid and _Pepsis_, 558; between _Rhyphus_- and _Mycetobia_-larvae, 463; of Syntomids to other Insects, 388 f.; of Tipulids and Hymenoptera, 475; between two kinds of ants, 162 Resting-larva, 306 Retinaculum, 316, 319, 420 Retort-shaped bodies, in mouth of Hemiptera, 535 Reuter, E., on classification of butterflies, 343 n. _Rhachicerus_, 480 _Rhagovelia plumbea_, 552 _Rhaphiorhynchus_, 483 _Rhegmatophila alpina_, 305, 386 _Rheumatobates bergrothi_, 553 Rhinomacerides, 291 _Rhinopsis_, 115; _R. ruficornis_, 169 _Rhinosimus_, 266 _Rhipicera mystacina_, 256 Rhipiceridae, 256 Rhipidiini, 267 _Rhipidioptera_, 543 Rhipiphoridae, 267 Rhipiphorides, 268 Rhipiptera, 298 [in error for Rhiphiptera] _Rhizophagus_, _232_ _Rhizotrogus_, 191 _Rhodoneura_, _405_ _Rhogmus_, 179, _180_ Rhopalocera, 340, 341 f. _Rhopalomelus angusticollis_, 206 Rhopalomeridae, 504 {622} _Rhopalosoma poeyi_, 100 Rhopalosomides, _100_ _Rhygchium brunneum_, _R. carnaticum_, _R. nitidulum_, _R. oculatum_, 77 _Rhynchites betulae_, 291, 292 Rhynchitides, 291 Rhynchophora, _190_, 277, 288 f. Rhynchophorous series, _240_ _Rhynchopsylla pulex_, 526 Rhynchota, 532 Rhyphidae, 478 _Rhyphus_, 463 Rhysodidae, _201_, 234 Riley, on _Epicauta_, 270, 271; on spermathecal bodies, 321; on Yucca-moth, 432 _Ripidius pectinicornis_, 269 Rippe, of Schäffer, 334 Robber-flies, 491 Rose-chafers, 200 _Rosema_, 401 Rostrum, 291, 472 Rothney, on _Ampulex_, 115; on _Sima_, 169; on _Sphex_, 110 Rothschild, N. C., on morphology of fleas, 523 n. Royal jelly, 66 _Rozites gongylophora_, 167 Ruby-wasps, 1 f. Rurales, _342_ Rutelides, _195_, 198

_Saccoderes_, 558; _S. tuberculatus_, 537 Saccus, 314 _Sagra splendida_, 279 Sagrides, _279_ _Salda_, _560_ Saldidae, _544_, 562 Salivary, duct, 320; gland, 320 Sand-flea, 525; -flies, 477 _Saperda populnea_, 285, 286 Sapromyzidae, _504_ _Sapyga quinquepunctata_, 100 Sapygides, 99 _Sarcophaga_, 510; _S. carnaria_, 510 Sarcophagidae, 510 _Sarcophila magnifica_, _S. wohlfahrti_, 510 _Sarcopsylla gallinacea_, _S. penetrans_, 525 Sarginae, 479 _Saropoda_, _32_ _Sarrothripus_, 410 Sasaki, on parasite of silkworm, 508 _Saturnia_, 307, 310; _S. pavonia_, 313, 374 Saturniidae, _368_, 372 Satyrides, 347 Sauba, or Sauva, ant, 137 Saunders, E., on feathered hairs, 11; on proboscis of bees, 16 Saunders, Sir S., on Hymenopterous larvae, 8 Scale, 131, 133, 315, 467; development of, 329 f.; -formation, 333; -holder, 331 Scale-Insects, 592 f.; enemy of, 356, 357, 417, 425, 430 Scalpella, 443 Scape, 441 Scaphidiidae, 229 _Scaphisoma agaricinum_, 229 Scaphium, 314 Scapulae, 312 Scarabaeidae, 194 f. Scarabaeini, 196 _Scarabaeus sacer_, 196, 197 Scatomyzidae, _504_ Scatophagidae, _504_ _Scatopse_, 477 _Sceliphron_, 112; _S. nigripes_, 91 Scenopinidae, 484 Schäffer, on structure of wings and nervures, 330 Schiödte, on Anoplura, 599 f.; on Hemiptera, 543 _Schistocerca peregrina_, enemy of, 506, 514 _Schizocarpus mingaudi_, 220 Schizometopa, _504_ _Schizoneura_, 589 Schizophora, 455 Schmidt-Schwedt, on _Donacia_, 280 _Schoenbergia_, 360, 361 Schoenobiinae, _425_ _Sciapteron_, 387 _Sciara militaris_, 464 Sciomyzidae, _504_ _Sciophila unimaculata_, 462 _Scolia bifasciata_, _S. haemorrhoidalis_, 97 Scoliidae, 93, 94 f. Scoliides, 97 f. Scolytidae, 294 Scopariidae, _421_ Scopariinae, _421_ _Scopelodes_, 401 Scopulipedes, _20_, 32 f. Screw-worm, 512 Scudder, on butterflies, 543 Scutata or Scutati, _546_ Scutellerides, 545 _Scutelligera_, 501 Scutellum, 307, 312, 537 Scutum, 307; S. proboscidis, 443 Scydmaenidae, 223 Scymnites, 238 _Scymnus minimus_, 238 Seasonal dimorphism or variation, 335 Seitz, on Syntomid resemblances, 388, 389 Semi-loopers, 415 Seminal duct, 321 Semi-pupa, 271 Semper, on development of wing, 333 Sense-organ, 442, 448; thoracico-abdominal, 414; in Uraniidae, 419 Sepsidae, _504_ _Sericaria mori_, 375 Sericteria, 325 {623} Seroot-fly, 482 Serricornia, _189_, _213_, _255_ _Sesia_, 387; _S. scoliaeformis_, 321 Sesiidae, 386, _388_, 370 (for Syntomidae), 389 Setae, 534 f.; aërostatic, 408 _Setina_, 410 Seventeen-year _Cicada_, 569 Sex, differences, 92, 95; production of, 32, 67; in larva, 325 Sexuparous, 586 Sharp, on classification of Dytiscidae, 213 n. Sheep, bot-fly, 517; -tick, 518 Shield, 592 Shoulder, -lappets, 312; -tufts, 312; of wing, 316, 319 _Siagona_, 206 Siculodidae, 423 Siebold, von, on Strepsiptera, 301 _Sigara minutissima_, 568 Sight, of _Pompilus_, 104 Silk-glands, 325 Silkworm, 375; affected by parasitic fly, 507, 508; Madagascar-, 405 _Silpha_, 221; _Silpha atrata_, _S. laevigata_, _S. lapponica_, 222; _S. obscura_, 222; _S. opaca_, _S. thoracica_, 222 Silphidae, 221 f., _252_, _256_ _Sima_, _168_; _S. leviceps_, stridulating organ, _169_; _S. rufonigra_, 169 Simuliidae, 477 _Simulium columbaczense_, 477 _Sinodendron cylindricum_, 194 Siphon, 563, 581, 589 Siphonaptera, 522 f. Siphonophora, 239 Siphunculata, 600 _Sitaris_, 33; _S. humeralis_, 272 _Sitodrepa_, 247 Skippers, 363 Slave-making ant, 149, 150, 163 Sloth, 430 Slug-worms, 402 Smallest Insect, 228 Smerinthini, 380 _Smerinthus populi_, 309, 381 Smith, F., on _Mellinus arvensis_, 123 Snails, enemies of, 205, 222, 510; parasite of, 495 Social, bees, 35; wasps, 78, 84 Sociales, _20_, 53 f. _Solanum dulcamara_, beetle on, 232 Soldiers, 132 Soldier-ant, 150 _Solenobia_, 395, 430 _Solenopsis fugax_, 137 Solitary wasps—see Fossores and Eumenidae Song, of _Cicada_, 572 _Soronia_, 232 Sound-organs, 448; of _Ageronia_, 354; of _Hecatesia_, 371; of _Cicada_, 573, 574—see also stridulating organs Sound-production, 155, 156; by _Aegocera_, 411; by Arctiidae, 410; by Sphingidae, 382—see also Stridulation Spalacopsini, 288 Spatula, 459 Spencer, Herbert, on Weismann, 143 _Spercheus emarginatus_, 218, 219 Spermatheca, 320, 321 _Spermophila_, 506 Sphaeridiides, _219_ Sphaeriidae, 227 _Sphaerites_, _223_ Sphaeritides, 229 _Sphaerius acaroides_, 227 Sphaerocarides, 279 _Sphecia_, 387 _Sphecius speciosus_, 123 _Sphecodes_, _21_, 22; _S. gibbus_, 23, 23; _S. rubicundus_, 22; _S. subquadratus_, 23 Sphegidae, 93, 107 f. Sphegides, 107 f. _Sphex coeruleus_, 110; _S. flavipennis_, 108; _S. lobatus_, 110; _S. maxillosus_, 108 Sphindidae, 245 Sphingidae, 309, 315, 316, _368_, 380 f. _Sphinx ligustri_, 380 Spider parasite, 490 _Spilosoma_, 408 Spinneret, 324, 325, 403, 417 _Spirachtha_, 227 Spiracles, 188, 191; of Diptera, 449 f.; of Hippoboscidae, 519; of Lepidoptera, 313, 314; of _Lipara_, 451; of _Nepa_, 564; of Thrips, 528 _Spondyliaspis_, 581 Spondylidae, 288 Springing plant-lice, 579 Spuler, on nervures, 317 n. Squama, 448 Squeakers, 209 _Staetherinia_, 401 Stag-beetles, 193 Stalk, 317, 319 Staphylinidae, _223_, 224 f. Staudinger, Schatz and Röber, on butterflies, 343 n. _Stauronotus maroccanus_, 489 _Stauropus fagi_, 385 _Stelis minuta_, 29; _S. nasuta_, 30, 43; _S. signata_, 30 Stelocyttares, 81 _Stenamma westwoodi_, _159_ _Stenopteryx hirundinis_, 519 _Stephostethus_, 240 Sternorhyncha, _544_ _Sterrhopteryx_, 394 Stethopathidae, 496 Stigmata—see Spiracles _Stigmatomma_, _180_ _Stigmus pendulus_, 128 Sting, 4, 5, 6, 58, 144; {624} development of, 8, 9 Stinging, 98; by _Calicurgus_, 102; by Pompilidae, 104; by _Sphex_, 109 Stingless bees, 61 Stink-gland, 257, 533; -vessel, 225 Stipes, 309 Stizinae, 123 Stomach, 320 _Stomoxys calcitrans_, 512 Stratiomyidae, 478 _Stratiomys_, 452 Straus-Durckheim, on _Melolontha_, 198 Strawberries, eaten by beetles, 205 Streblidae, 521 Strepsiptera, _189_, 298 f. _Streptoperas_, 401 Stridulating organ, of _Myrmica_, 133; of _Heterocerus_, 243; of _Passalus_-larva, 192; of _Sima leviceps_, 169 Stridulation, of ants, 134; of _Corixa_, 568; of Criocerides, 281; of Dynastides, 199; of _Geotrupes_, 195; of Ipides, 232; of _Lomaptera_, 200; of Longicorns, 287; of larva of _Lucanus cervus_, 194; of Megalopides, 282; of _Melolontha_-larva, 198; of _Mutilla_, 94; of _Pelobius_, 208; of _Phonapate_, 246; of _Phyllomorpha_, 548; of _Praogena_, 264; of _Siagona_, 206; of _Trox_, 195 Strigil, 568 Striphnopterygidae, _376_ _Strongylognathus huberi_, _S. testaceus_, 162 _Strumigenys_, 170 Style, 442 Stylopidae, 298 Stylopised bees, 26 _Stylops dalii_, 299 _Styx infernalis_, 340, 358 _Suana_, 405 Subcostal nervure, 318 Submedian nervure, 318 Suboesophageal ganglion, 320 Sucking-stomach, 311, 449 Suction by Lepidoptera, 311 Suctoria, 526 Supericornia, 546 Swallow-flies, 519 Swarming of wasps, 70 n. Swarms, 62, 65, 67, 80, 135, 467, 505, 584 Swift-moths, 396 Symbiosis, of ants and plants, 139; of bee and Acarid, 70. See also Ants'-nest Insects, and Association _Symbius blattarum_, 269 Symphily, 183 Synecthry, 183 _Synemon_, 371 _Synoeca cyanea_, nest, 82 _Syntelia westwoodi_, 229 Synteliidae, 229 Syntomidae, 339 n., _369_, 388 _Syntomis phegea_, 390 Syringe, 535, 536 Syrphidae, 439, 498 f. _Systoechus oreas_, 489 _Systropus crudelis_, 489

Tabanidae, 481, 492 _Tabanus_, 482 Tachinidae, 507, _514_ _Tachysphex panzeri_, 117 _Tachytes_, 116; destroyer of, 275; _T. australis_, 113, 117; _T. pectinipes_, 117 Tachytides, 116 _Taenia_, fleas as hosts of, 526 _Tajuria diaeus_, pupa, 357 _Taleporia_, 395 Taleporiidae, 430 Tanypezidae, _504_ Taphroderides, 296 _Tapinoma erraticum_, 157 Tarantula-killer, 105 _Tarphius_, 233 _Tarsolepis_, 383 Taschenberg, on anatomy of flea, 523 n. _Tascina_, _372_ Tea-plant bug, 562 _Teara melanosticta_, 408 Tegula, 71, 187, 307, 311, 312, 447 Tegmina, 539 Teleodont, 193 Telephorides, _248_ _Telmatophilus_, 235 _Temnochila coerulea_, 232 Temnochilides, _233_ _Tenebrio molitor_, 263 Tenebrionidae, 263 _Tenebroides mauritanica_, 232 Tentacle, maxillary, 309, 432 Tenthredinidae, parasite of, 4 Terebrantia, 531 Termites, 203, 206, 227, 231 Terrifying attitude, 384 Tesseratomides, 546 Testes, 321, 324, 400, 429; in larva, 325 _Tetanocera ferruginea_, 504 Tetanoceridae, _504_ _Tetragona_, _53_, _61_ Tetramera, _190_ _Tetramorium caespitum_, 160, 163 Tettigometrides, _567_ _Teucrium_, bug and galls on, 550 _Thais_, pupation of, 363 _Thanaos_, _342_; _T. tages_, androconia, 332 Therevidae, 484 _Thiridopteryx_, 420 Thomas, on androconia, 331 Thorictidae, 236 _Thorictus_, 236 Thrips, 526 f.; _Thrips lini_, 531; _T. secalina_, 530 Throscides, _260 Thyatira batis_, _T. derasa_, 386 {625} Thymaridae, 392 Thynnides, 96 Thyreophoridae, _504_ Thyrididae, _370_, 404 _Thyridopteryx ephemeraeformis_, 394 Thysanoptera, 526 f. Tiger-beetles, 201 f. Tiger-moths, 409 _Tillus elongatus_, 253, 254 Tinaegeriidae, _370_, 387 _Tinea_, 305; _T. pellionella_, 429, 430; _T. vastella_, 430; _T. vivipara_, 430 Tineidae, _340_, _370_, _394_, _427_, 428 Tineodidae, 423 _Tineola biselliella_, 430 Tingidae, 549 _Tipula brobdignagia_, 475 Tipulidae, 471 f.; T. Brevipalpi, 472, 473; T. Longipalpi, 472, 475 Tipulinae, 475 _Tiresias serra_, 241 _Titanus giganteus_, 287 _Tithorea_, 346 Tomicides, 295 _Tomognathus sublaevis_, 161 Tongue, 309 Tortoise-shell butterflies, 352 Tortricidae, _340_, _395_, 427, _432_ Tortricina, _395_ _Toxorrhina_, 472 _Toxotrypana_, 506 _Trechus_, 205 Trichiini, 200 _Trichocera_, 473 _Trichodes alvearius_, _T. ammios_, _T. apiarius_, 254 _Trichophaga tapetzella_, 430 Trichoptera, 306, _425_ Trichopterygidae, 227 _Trichopteryx fascicularis_, 227 Trichroism, 351 Trichterwickler, 294 _Trichura_, 389, 390 Trictenotomidae, 275 _Triecphora_, 543 _Trigona_, _53_, _61_; _T. carbonaria_, 63; _T. crassipes_, 65; _T. mosquito_, 62 Trimera, _238_, 544 _Trimeria_, _89_ _Trineura aterrima_, 494 _Triodites mus_, 489 _Trioza rhamni_, 580 _Triphaena_, 415 _Triphleps_, 530 _Tritoma bipustulata_, 236 Triungulin, 262, 268, 270, 271, 272, 299, 300 Trochalopoda, _543_, _544_ Trochanter, 307; divided, 123 _Trochilium_, 387 Trogini, _195_ Trogositidae, 232, 235 _Trogosita mauritanica_, 232 Tromoptera, 457 Trophi—see Mouth-parts _Trox_, stridulation, 195 Truffle-beetle, 222 Trumpeter bumble-bee, 58 _Trypanaeus_, 230 Trypanidae, 395 Trypetidae, _504_, 506 Trypoxylonides, 118 _Trypoxylon_, 118; _T. albitarse_, 118; _T. figulus_, 119 Tse-tse fly, 512, 513 Tubulifera, _1_ f. Tubulifera (Thrips), 531 Tulip-tree, tubes on, 578 Turkey-gnats, 477 Turnip-flea, 278 Tusser, or Tussore, silk, 374 _Tympanoterpes gigas_, 572 _Typhlatta_, _179_, _180_ _Typhlopone_, 178, 179, 180

_Ugimyia sericariae_, 507 Ulidiidae, _504_ _Ulopa_, _578_ Uncus, 314 _Urania rhipheus_, 419 Uraniidae, _368_, 419 Uric acid pigments, 357 _Urodon_, _278_ Uzel, on Thysanoptera, 527

_Vanessa_, 352; larva, 354—see also _Pyrameis_ and _Araschnia_ _Vanessula_, 356 Vapourer-moths, 407 Variation, of _Anomma burmeisteri_, 179; of _Bombus_, 58; of larvae, 336; of _Sphecodes_, 23; of male and worker ants, 160; of workers and females, 162; due to parasites, 26; of larva and imago, 408; generic, 401; local, 398; in nervuration, 414; and dimorphism in Geometrid-larvae, 412; of mandibles of Lucanidae, 193; in colour of Psyllidae, 579; trichroism of hind wings, 351; in size of Brenthidae, 297; of time and form in _Cicada_, 570; in wings, 540; as to winged or wingless, 531; change in, 414; seasonal, 335 Vasa deferentia, 321 Veils, 493 Veins—see nervures _Velia currens_, 552 _Velleius dilatatus_, 227 Verhoeff, on _Agenia_, 106; on _Halictus_, 25; on Siphonophora, 239; on _Stelis minuta_, 29; on terminal segments of beetles, 186 _Vermileo degeeri_, 481 _Vermipsylla alakurt_, 523, 526 {626} Verson, on rudiments of wings, 328 Vertebrates, larvae of Diptera, attacking, 506, 510, 512, 514, 517, 520; tick-fleas on, 526 _Vespa_, nests of, 79, 83; _V. austriaca_, 81, 88; _V. crabro_, 81; _V. germanica_, 79 Vespidae, 78 Viviparous, Aphids, 583; fly, 506, 511, 513, 518 f.; moths, 430; Staphylinidae, 227 Voice—see Song, Sound-organs, Stridulation _Volucella_, 500; _V. bombylans_, 441

Wagner, on morphology of fleas, 523 n.; on paedogenesis, 460 Walker, J. J., on _Halobates_, 552 Wallace, on flight of Hesperiidae, 364 Walsingham, Lord, on Tortricidae, 427 Walter, on mouth of Lepidoptera, 308, 310 Wandering ants, 175 f. Wanzenspritze, 536 Wasmann, on Ants'-nest Insects, 181 n., 183; on _Lomechusa_, 142, 226; on Weismann, 143 Wasps, 71 f. Wasps'-nest, beetle, 235; Insect, 268 Water-scorpion, 563 Wax, 65, 575, 576, 597 Wax-glands, 589 Wax-hairs, 580 Wedde, on mouth of Hemiptera, 535 Weeping-trees, 577 Weevil, biscuit-, 247; pea-, 277 Weinland, on halteres, 448 Wet- and dry-season forms, 336 Whirligig-beetle, 215 White wax, 576, 597 Whittell, on _Pelopaeus_ and _Larrada_, 117 Wielowiejski, on luminous organs, 250 Wing-cases, of beetles, 186, 270 Wing, of bugs, 539; of Diptera, 447; of Lepidoptera, 315 f.; development of, 328; structure of, 329 Wingless—see Apterous Wingless and winged Aphids, 584 Wing-nervures—see Nervures Wing-rib, 330, 333 Wing-veins—see Nervures Winter-gnats, 473 Winter-moth, 414 Winter-mother, 586 Wire-worm, 258 Wood-ant—see _Formica rufa_ Wood-leopard moth, 309, 395 Woodpecker, Diptera in, 506 Workers, 54, 66, 67, 79, 85, 132, 140 Worm-eaten furniture, 248

_Xantharpyia straminea_, parasite of, 521, 522 _Xenos_, 303; _X. rossii_, 299, 301 _Xestobium_, _248_ _Xylocopa_, 32, 34, 70; submentum of, 14; _X. chloroptera_, 34; _X. violacea_, 33 _Xylodiplosis_, 458, 459 Xylophagidae, 479 Xylophaginae, 480 Xylophilidae, 266 _Xylotrupes gideon_, 199

Yellow-fever-fly, 464 _Yolinus_, 558 Young carried, 556 Yucca-moth, 432

_Zabrus_, 205 _Zaitha anura_, 566 _Zelotypia staceyi_, 396 _Zemioses celtis_, 296 _Zeuzera aesculi_, 309, 395 Zeuzeridae, 395 Zygaenidae, _369_, 388, 390, _392_, _394_ _Zygia_, 253

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NOTES

[1] Systematic monograph, Mocsáry, Budapest, 1889. Account of the European Chrysididae, R. du Buysson in André, _Spec. gen. Hym._ vol. vi. 1896.

[2] _Ent. Mag._ vi. 1869, p. 153.

[3] _Ann. Sci. Nat._ (7) ix. 1890, p. 1.

[4] _C. R. Ac. Paris_, cxviii. 1894, p. 873.

[5] _Trans. ent. Soc. London_, 1873, p. 408.

[6] _Zeitschr. wiss. Zool._ xxv. 1875, p. 184.

[7] _Morph. Jahrb._ xxiv. 1896, p. 192.

[8] _Zeitschr. wiss. Zool._ xxx. 1878, p. 78.

[9] _Proc. ent. Soc. Washington_, iii. 1896, p. 334.

[10] _Trans. ent. Soc._ 1878, p. 169.

[11] The mode of wetting the pollen is not clear. Wolff says it is done by an exudation from the tibia; H. Müller by admixture of nectar from the bee's mouth. The latter view is more probably correct.

[12] In studying the proboscis the student will do well to take a _Bombus_ as an example; its anatomy being more easily deciphered than that of the honey-bee.

[13] Leuckart proposed the term lingula; but the word gives rise to the impression that it is a mistake for either lingua or ligula. Packard calls the part "hypopharynx."

[14] For figures and descriptions of the proboscides of British bees, refer to E. Saunders, _Jour. Linn. Soc._ xxiii. 1890, pp. 410-432, plates III.-X.: and for details of the minute structure and function to Cheshire, _Bees and Bee-keeping_, vol. i.

[15] Breithaupt, _Arch. Naturges._ lii. Bd. i. 1886, p. 47.

[16] See Fig. 26, p. 71.

[17] _Bull. Mus. Paris_, i. 1895, p. 38.

[18] _C.R. Ac. Paris_, lxxxvii. 1878, pp. 378 and 535.

[19] _Catalogus Hymenopterorum_, Leipzig, 10 vols. 1892-96; _Bees_, vol. x.

[20] _Zool. Jahrb. Syst._ iv. 1891, p. 779. This paper is a most valuable summary of what is known as to the habits of European solitary bees, but is less satisfactory from a systematic point of view.

[21] _Bull. Soc. ent. France_, 1894, p. cxv.

[22] Marchal, _Rev. Sci._ 15th February 1890, and Ferton, _t.c._ 19th April.

[23] _C.R. Ac. Paris_, lxxxix. 1879, p. 1079, and _Ann. Sci. Nat._ (6), ix. 1879, No. 4.

[24] _Act. Soc. Bordeaux_, xlviii. 1895, p. 145.

[25] _Verh. Ver. Rheinland_, xli. 1884, p. 1.

[26] It is impossible for us here to deal with the question of the origin of the parasitic habit in bees. The reader wishing for information as to this may refer to Prof. Pérez's paper, _Act. Soc. Bordeaux_, xlvii. 1895. p. 300.

[27] Refer to p. 70 _postea_, note, as to a recent discovery about _Xylocopa_.

[28] _Souvenirs entomologiques_. 4 vols. Paris, 1879 to 1891.

[29] The "_Chalicodome des galets_" or _C_. "_des murailles_" of the French writer; in some places he speaks of the species as being _C. muraria_, in others as _C. parietina_.

[30] _Trans. Zool. Soc. London_, vii. 1870, p. 178.

[31] _Mt. Ver. Steiermark_, xxxi. 1882, p. 69.

[32] _Zool. Anz._ vii. 1884, p. 312.

[33] _SB. Ges. Wien._ xxxviii. 1888, p. 34.

[34] _Ent. Nachr._ xii. 1886, p. 177.

[35] _Tr. ent. Soc. London_, 1868, p. 133.

[36] _Tr. ent. Soc. London_, 1884, p. 149.

[37] _Ann. Soc. ent. France_ (5), iv. 1874, p. 567.

[38] See Pérez, _Act. Soc. Bordeaux_, xxxiii. 1880, p. lxv.; and Cameron, _Tr. Soc. Glasgow_, n. s. ii. 1889, p. 194.

[39] _Ann. Nat. Hist._ (6), xix. 1897, p. 136.

[40] Janet has suggested that the folding is done to keep the delicate hind-margins of the wings from being frayed.

[41] _Zool. Anz._ xix. 1896, p. 449. See also note, _antea_, p. 70.

[42] _Monographie des guêpes sociales_, Geneva, 1853-1858, pp. cc. and 356, plates i.-xxxvii.

[43] Hence probably the great difference in the abundance of wasps in different years: if a period of cold weather occur during the early stages of formation of a wasp family, operations are suspended and growth delayed; or death may even put an end to the nascent colony.

[44] _CR. Ac. Paris_, cxvii. 1893, p. 584; _op. cit._ cxxi. 1895, p. 731; _Arch. Zool. exper._ (3) iv. 1896, pp. 1-100.

[45] Kumagusu Minakata, in _Nature_, l. 1894, p. 30.

[46] As this work is passing through the press we receive a book by Mr. and Mrs. Peckham on _The Instincts and Habits of the Solitary Wasps_, Madison, 1898. They are of opinion that, in the case of some species, it does not matter much whether the victim is or is not killed by the stinging.

[47] _P. ent. Soc. Washington_, iii. 1896, p. 303.

[48] Monograph by Lucas, _Berlin ent. Zeitschr._ xxxix. 1894.

[49] "Die Gattungen der Sphegiden," _Ann. Hofmus. Wien._ xi. 1896, pp. 233-596. Seven plates.

[50] We will take this opportunity of correcting an error in the explanation of Fig. 333 of the preceding volume, showing the propodeum, etc. of _Sphex chrysis_. _f_ points to a division of the mesonotum, not of the metanotum, as there stated.

[51] _Pelopaeus_ disappears from the new catalogue of Hymenoptera as the name of a valid genus; its species being assigned to _Sceliphron_ and various other genera. We have endeavoured, as regards this name, to reconcile the nomenclature of previous authors with that used in the new catalogue by placing the generic name adopted in the latter in brackets.

[52] When a second cell is more or less perfectly marked out, the cell with which it is connected is said to be appendiculate. The nervures frequently extend beyond the complete cells towards the outer margin, forming "incomplete" cells; only complete cells are counted, except when "incomplete" is mentioned.

[53] See on this point the note on p. 130.

[54] The pupae and cocoons of ants are usually called by the uninstructed, "ants' eggs." In this country they are used as food for pheasants.

[55] The parthenogenetic young produced by worker females are invariably of the male sex.

[56] The student must recollect that the winged female ants cast their wings previously to assuming the social life. The winglessness of these females is a totally different phenomenon from that we here allude to.

[57] See Forel, _Verh. Ges. deutsch. Naturf._ lxvi. 1894, 2, pp. 142-147; and Emery _Biol. Centralbl._ xiv. 1894, p. 53. The term ergatoid applies to both sexes; a species with worker-like female is ergatogynous; with a worker-like male ergatandrous.

[58] _Nature_ li. 1894, p. 125.

[59] _Biol. Centralbl._ xv. 1895, p. 640.

[60] Prof. Forel has favoured the writer by informing him of several cases of these rare intermediate forms he has himself detected.

[61] _Biol. Centralbl._ xiv. 1894, p. 53.

[62] Forel's latest views on this subject will be found in the _Ann. Soc. ent. Belgique_ xxxvii. 1893, p. 161; the very valuable paper by Emery, in _Zool. Jahrb. Syst._ viii. 1896, p. 760.

[63] _Ann. Soct. ent. France_, 1893, p. 467.

[64] _Ann. Soc. ent. France_, 1893, _Bull._ p. cclxiv.

[65] Forel, _J. Bombay Soc._ viii. 1893, p. 36.

[66] See von Ihering, _Berlin. ent. Zeitschr._ xxxix. 1894, p. 364; and Forel, _Ann. Soc. ent. Belgique_, xl. 1896, p. 170.

[67] _Ann. Soc. ent. Belgique_, xxxvii. 1893, p. 163.

[68] _Bih. Svenska Ak._ xxi. 1896, Afd. iv. No. 4.

[69] Until recently this genus was generally known as _Atta_, but this name is now applied to the leaf-cutting ants, that were formerly called _Oecodoma_.

[70] Forel, _Bull. Soc. Vaudoise_, xxx. pp. 29-30, 1894.

[71] _Tr. ent. Soc. London_, 1893, pp. 365-467.

[72] For a valuable revision of _Dorylus_ and its allies see Emery, _Zool. Jahrb. Syst._ viii. 1895, pp. 685, etc. We, however, doubt the wisdom of extending the sub-family so as to include _Cerapachys_, _Parasyscia_, etc.

[73] A Catalogue of Myrmecophilous and Termitophilous Arthropods was published by Wasmann, Berlin 1894.

[74] For a summary of this subject see Wasmann, _Congr. internat. Zool._ iii. 1896, pp. 411-440.

[75] For explanation of this term see vol. v. p. 524.

[76] An interesting exception occurs in the Malacodermidae, where this coadaptation is wanting, or is imperfect; they are frequently considered to be the most primitive of existing beetles.

[77] In a series of memoirs in various German periodicals during the last five or six years (see especially _Deutsche ent. Zeit._ 1893 and 1894, also subsequent years of _Arch. Naturges._). It should be noticed that in the course of his studies Verhoeff has modified some of his earlier views.

[78] We consider this term inferior to Tetramera for nomenclatorial purposes.

[79] _Danske Selsk. Skr._ (6), viii. No. 1, 1895.

[80] _Horae Soc. ent. Ross._ xiv. 1879, p. 15.

[81] In this sub-family there are numerous forms in which the elytra cover the pygidium, and in which the number of conspicuous ventral segments is reduced to five or even four. We use the term Coprides as equivalent to the "Laparosticti" of Lacordaire (_Gen. Col._ iii. 1856); it thus includes the "Coprini" and "Glaphyrini" of the _Catalogus Coleopterorum_, vol. iv. Munich, 1869.

[82] _Considérations genérales sur l'anatomic comparée des animaux articulés_, etc., Paris 1828, 4to. xix. and 435 pp., and Atlas of ten (xx.) plates, and 36 pp.

[83] Raspail, _Mém. soc. zool. France_, vi. 1893, pp. 202-213.

[84] _Ann. soc. ent. France_, (v.) iv. 1874, p. 39.

[85] In Theratides this outer lobe is in a rudimentary state, like a seta.

[86] The first portion of a classification of Cicindelidae by Dr. Walther Horn, _Revision der Cicindeliden_, Berlin, 1898, has appeared since this was written.

[87] _Natural History of aquatic Insects_, 1895, p. 376.

[88] _Tr. Amer. ent. Soc._ xv. 1888, p. 18.

[89] _Op. cit._ v. 1881, p. 91; cf. Sharp, _Tr. ent. Soc. London_, 1882, p. 61.

[90] _P. ent. Soc. Washington_, ii. 1892, p. 341.

[91] _Descent of Man_, i. 1890, p. 338; The views of Landois and Recker, _Arch. f. Naturgesch._ lvii. 1, 1891, p. 101, are erroneous.

[92] See _J. Linn. Soc. Zool._ xiii. 1876, p. 161.

[93] For many particulars as to respiration of _Dytiscus_, and peculiarities of the larva see Miall, _Aquatic Insects_, 1895, pp. 39, etc. (In the figure given on p. 60 the large stigma on the terminal segment of the abdomen is omitted, though it is referred to in the text.)

[94] For classification and structure see Sharp, "On Dytiscidae," _Sci. Trans. R. Dublin Soc._ (2) ii. 1882.

[95] Descriptions of larvae that may possibly be those of Paussids have been published by Xambeu, _Ann. Soc. Linn. Lyon_, xxxix. 1892, p. 137, and Erichson, _Arch. Naturgesch._ xiii. 1847, p. 275.

[96] _Arch. Mus. Paris_ (2), viii. and ix. 1887.

[97] For classification and monograph of the family, see Régimbart, _Ann. Soc. ent. France_, 1882, 1883, and 1886. For a catalogue, Séverin, _Ann. Soc. ent. Belgique_, xxxiii. 1889.

[98] _Ann. Soc. ent. France_, xxi. 1852, p. 619.

[99] Horn, _Tr. Amer. ent. Soc._ xv. 1888, p. 23; Riley, _Insect Life_, i. 1889, p. 300.

[100] _Insect Life_, i. 1889, pp. 200 and 306.

[101] _Tr. Amer. ent. Soc._ viii. 1880, pp. 219-321.

[102] Westwood, _Tr. ent. Soc. London_ (N.S.) iii. 1855, p. 90; Wasmann, _Krit. Verzeichniss Myrmekoph. Arthropod._ 1894, p. 121.

[103] _Rev. ent. franc._ ix. 1890.

[104] _Die Käfer von Mitteleuropa_: II. _Familienreihe, Staphylinoidea._ Vienna, 1895 and 1899.

[105] _Vergleichende Studien über Ameisengäste_, Nijhoff, 1890; and _Tijdschr. ent._ xxxiii. 1890, pp. 93, etc.; _Biol. Centralbl._ xv. 1895, p. 632.

[106] Schiödte, _Ann. Sci. Nat. Zool._ (4) v. 1857, p. 169.

[107] _Biol. Centr. Amer. Col._ ii. pt. i. 1888, p. 156.

[108] Monograph, _Trichopterygia illustrata_, by A. Matthews, London, 1872.

[109] For further information refer to Matthews, _An Essay on_ Hydroscapha, London, 1876, 20 pp. 1 pl.

[110] _Ann. Nat. Hist._ (5) xix. 1887, p. 115.

[111] _Larves de Coléoptères_, 1878, p. 11, pl. i.

[112] _Biol. Centr. Amer. Col._ ii. pt. i. p. 438.

[113] The family was monographed by the Abbé de Marseul in _Ann. Soc. ent. France_, 1853-1862, but great additions have been made since then.

[114] For characters of larvae of various genera, see Perris, _Larves, etc._ p. 24.

[115] _SB. Ak. Wien._ xxiv. 1857, p. 330.

[116] Catalogue of Trogositidae, by Leveillé, in _Ann. Soc. ent. France_, 1888, p. 429.

[117] For classification, see Sharp, _Biol. Centr. Amer. Col._ ii. pt. i. 1894, p. 443.

[118] See Ganglbauer, _Käf. Mitteleuropas_, i. p. 530, as well as Leconte and Horn _Classification_, etc., p. 130.

[119] Perris, _Larves, etc._, p. 75.

[120] Ritsema, _Catalogue of_ Helota, _Notes Leyden Mus._ xiii. 1891, p. 223, and xv. 1893, p. 160.

[121] _Zool. Anz._ xviii. 1895, p. 244.

[122] Gerstaecker, _Monographie der Endomychiden_, Leipzig, 858, 1433 pp. Since this work was published, the species known have been multiplied two or three times.

[123] _Stettin. ent. Zeit._ xlii. 1881, pp. 104-112.

[124] It is probable that we do not know more than the fiftieth part of the existing species, most of which lead lives that render them very difficult to find.

[125] _Bull. ent. ital._ 1886, p. 406, and _Ent. Zeit. Stettin_, xliii. 1887, pp. 201-206. Emery does not mention the name of the species, but we presume it to be the common Italian fire-fly, _Luciola italica_.

[126] _Zeitschr. wiss. Zool._ xxxvii. 1882, p. 354; also Emery, _op. cit._ xl. 1884, p. 338. For another theory as to the luminescence, see p. 259.

[127] _Bull. Soc. Zool. France_, xii. 1887, p. 137, _postea_.

[128] _Deutsche ent. Zeitschr._ xxxii. 1888, pp. 145-167.

[129] _Ent. Mag._ xxiv. 1887, p. 148.

[130] _Larves des Coléoptères_, 1878, p. 208.

[131] _Ann. Soc. ent. France_, 1894, p. 7.

[132] Perris, _Ann. Soc. ent. France_ (2) ix. 1851, p. 48.

[133] _Arch. Naturgesch._ xlviii. 1, 1882, p. 371.

[134] "Les Élatérides lumineux," _Bull. Soc. Zool. France_, xi. 1886; also _Leçons de Physiologie générale_, Paris, 1898, and _C.R. Ac. Sci._ cxxiii. 1896, p. 653.

[135] It seems impossible to understand the morphology of the anterior segments by mere inspection; the anterior spiracle being seated on the segment behind the broad thorax. Considerable difference of opinion has prevailed as to what is head, what thorax; the aid of embryology is necessary to settle the point. The larva described by Westwood (_Mod. Classif._ i. 1839, p. 229), and figured as probably _Buprestis attenuata_ is doubtless a Passalid.

[136] Casey has examined the wings in the genus _Blapstinus_ (an "apterous" genus), and found that the wings are extremely varied in development, according to the species; in no case, however, did they appear to be capable of giving more than a laboured and feeble flight.—_Ann. New York Ac._ v. 1890, p. 416.

In _Eleodes_, though the meso- and meta-notum are formed of delicate membrane, the wings exist as minute flaps, requiring some examination for their detection.

[137] _Ann. Nat. Hist._ (4) vi. 1870, p. 314; and _Ent. Mag._ xxvii. 1891, p. 18.

[138] _Mitt. Schweiz. ent. Ges._ iv. 1876, p. 556.

[139] _Ann. Soc. ent. France_, lx. 1891, p. 447.

[140] "On the Natural History, Anatomy, and Development of the Oil-Beetle, _Meloe_," _Tr. Linn. Soc._ xx. 1851, p. 297; and xxi. 1853, p. 167.

[141] _Rep. U.S. ent. Commission_, i. 1878, p. 297.

[142] _Amer. Nat._ xvii. 1883, p. 790.

[143] For illustration of this metamorphosis, see Vol. V. p. 159 of this work.

[144] _Les Insectes Vésicants_, Paris 1890, 554 pp. Parts of this work were previously published in _J. de l'Anat. Phys._, xxi. xxii. xxiii. 1886 and 1887.

[145] _Genera des Coléoptères (Suites à Buffon)_, x. Paris, 1874, p. 15.

[146] _Berlin. ent. Zeit._ 1887, p. 325, and 1889, p. 299.

[147] _Ann. Soc. Liége_, x. 1855, p. 260.

[148] _Mem. Soc. Liége_, xvi. 1861, p. 387.

[149] Packard, 5th Rep. _U.S. Ent. Comm._ 1890, p. 689.

[150] Not a growing tree, but the instrument used for stretching boots.

[151] _Berlin. ent. Zeitschr._ xli. 1896, SB. p. 22.

[152] Sharp, _Ann. Soc. ent. Belgique_, xxviii. 1884, CR. p. cvii.

[153] For a more extensive account of _Rhynchites betulae_ and others refer to Wasmann. _Der Trichterwickler_, Münster, 1884, and Debey, _Beiträge zur Lebensund Entwickelungsgeschichte ... der Attelabiden_, Bonn, 1846. The first includes an extensive philosophical discussion; the second is a valuable collection of observations.

[154] _Bull. U.S. Dep. Agric. ent._ New series, No. 7, 1897.

[155] Perris, _Ann. Sci. Nat._ (2) xiv. 1840, p. 89, pl. iii.

[156] In the males of the genus _Cedeocera_ the tips of the elytra are drawn out into processes almost as long as the elytra themselves, and rivalling the forceps of earwigs.

[157] The stature of the individuals of the same species is, in some of these Brenthidae, subject to extreme variation, especially in the males, some individuals of which—in the case of _Brenthus anchorago_—are five times as long as others.

[158] This remark applies to the Strepsiptera parasitic on Hymenoptera: nothing whatever is known as to the life-histories of the species that attack Hemiptera.

[159] Although not an invariable, it seems that it is a general rule that the _Stylops_ produced from the body of one individual are all of one sex; it has even been stated that female bees produce more especially female _Stylops_, and male bees male _Stylops_. If any correlation as to this latter point exist, it is far from general.

[160] Von Siebold, _Arch. Naturges._ ix. 1843, pp. 137-161. Nassonoff's recent paper is in Russian, but so far as we can gather (cf. _Zool. Centralbl._ i. 1894, p. 766), it does not add greatly to the data furnished by von Siebold.

[161] _Ent. Meddel._ v. 1896. p. 148, and _Ov. Danske Selsk._ 1896, p. 67.

[162] _Horae Soc. ent. Ross._ xiv. 1879, p. 14.

[163] Named by Mr. Distant _Callidea baro_; according to the Brussels catalogue of Hemiptera, _Chrysocoris grandis_ var. _baro_.

[164] Kellogg, _Kansas Quarterly_, ii. 1893, p. 51, plate II.

[165] _Jena. Zeitschr. Naturw._ xviii. 1885, p. 751.

[166] The writer is not quite convinced that the supposed mandibles of these Macrolepidoptera are really entitled to be considered as such.

[167] _Tr. ent. Soc. London_, 1893, p. 263.

[168] _Amer. Natural._ xxix. 1895, p. 637. It should be recollected that many Lepidoptera do not possess any proboscis.

[169] _Jena. Zeitschr. Naturw._ xviii. 1885, p. 168.

[170] _Amer. Natural._ xiv. 1880, p. 313.

[171] For an account of the structures at the tip of the proboscis of this moth, and of the beautiful manner in which the lobes of the maxillae are dovetailed together, see Francis Darwin, _Quart. J. Micr. Sci._ xv. 1875, p. 385. For details as to numerous proboscides, and as to the difficulties that exist in comprehending the exact mode of action of the organ, refer to Breitenbach's papers, especially _Jena. Zeitschr. Naturw._ xv. 1882, p. 151.

[172] See Cholodkovsky, _Zool. Anz._ ix. p. 615; Haase, t.c. p. 711; also Riley, _P. ent. Soc. Washington_, ii. 1892, p. 310.

[173] _Fourth Rep. U.S. Entom. Commission_, 1885, p. 49.

[174] _C.R. Ac. Sci. Paris_, cxviii. 1894, p. 360; and his _Thesis_, Bordeaux, 1895.

[175] _C.R. Ac. Sci. Paris_, cxviii. 1894, p. 542.

[176] _Fauna of British India_, Moths, i. 1892, p. 6.

[177] It is impossible for us to treat of the difficulties that exist on this point, and we must refer the student to the pamphlet, "The Venation of the Wings of Insects," by Prof. Comstock, Ithaca, 1895, being a reprint, with an important prefatory note, from the _Elements of Insect Anatomy_, by J. H. Comstock and V. L. Kellogg, also to Packard's discussion of the subject in _Mem. Ac. Sci. Washington_, vii. 1895, pp. 84-86. The method of Spuler, alluded to in these two memoirs, is based on development, and, when extended, will doubtless have very valuable results. See Spuler, _Zeitschr. wiss. Zool._ liii. 1892, p. 597.

[178] The structure and development of scales and nervures is dealt with as part of the brief study of the development of the wing, on p. 329, etc.

[179] The internal anatomy of Lepidoptera has not been extensively studied. For information refer to Dufour, _C.R. Ac. Paris_, xxxiv. 1852, p. 748; Scudder, _Butt. New England_, i. 1889, p. 47; Minot and Burgess, _Fourth Rep. U. S. Entom. Comm._ 1885, p. 53.

[180] _Tr. Linn. Soc. London_ (2), v. 1890, p. 143.

[181] _P. ent. Soc. Washington_, ii. 1892, p. 305.

[182] _Acta Ac. German._ li. 1887, p. 238.

[183] _Ann. Soc. ent. France_, 1887, pp. 384-404, Pl. 7.

[184] _Isis_, 1845, p. 835.

[185] For anatomy of caterpillars refer to Lyonnet's famous work, _Traité anatomique de la chenille qui ronge le bois de saule_, La Haye, 1762.

[186] See Plateau, _Bull. Ac. Belgique_, xv. 1888, p. 28; in reference to structure of ocelli, Blanc, _Tête du Bombyx mori_ ... 1891, pp. 163, etc.; and Landois in _Zeitschr. wiss. Zool._ xvi. 1866, p. 27.

[187] _Entwickelungsgeschichte der Schmetterlinge_, Cassel, 1815.

[188] _Tr. Linn. Soc. London, Zool._ 2nd Ser., v. 1890, pp. 147, 148.

[189] For information as to the structure and function of the silk-vessels, refer to Helm, _Zeitschr. wiss. Zool._ xxvi. 1876, p. 434; and Gilson, _La Cellule_, vi. 1890, p. 116.

[190] _Jahresber. Schlesisch. Ges._ lviii. 1881, p. 116.

[191] The student will find important information as to the varieties of external form of pupae in Dr. T. A. Chapman's writings; see especially _Tr. ent. Soc. London_, 1893, 1894, and 1896.

[192] Latter, _Tr. ent. Soc. London_, 1895, p. 399.

[193] _Bull. Soc. Vaudoise_, xxx. 1894, No. 115.

[194] _Zeitschr. wiss. Zool._ liii. 1892, p. 623.

[195] _Zool. Jahrb. Anat._ iii. 1889, p. 646.

[196] _Amer. Natural._, xxvii. 1893, p. 1018.

[197] _Amer. Natural._, xxxii. 1898, p. 256.

[198] _Zeitschr. wiss. Zool._ viii. 1857, p. 326.

[199] _Phil. Trans._ 186 B, 1896, No. 15.

[200] _Natural Science_, viii. 1896, p. 94.

[201] _Bull. Soc. ent. France_, 1896, p. 257.

[202] _Ent. Record_, vi. 1895, p. 258.

[203] _Trans. ent. Soc. London_, 1892, p. 293, etc.

[204] The term mimicry is sometimes used in a wider sense; but we think it better to limit it to its original meaning. The word is a most unfortunate one, being both inadequate and inaccurate.

[205] _Trans. Linn. Soc._ xxiii. 1862, p. 507.

[206] A summary of the chief aspects of the question is contained in Beddard's _Animal Coloration_, London, 1892. An account of the subject with numerous illustrations has been given by Haase, "Untersuchungen über die Mimicry," _Bibl. Zool._ iii. 1893, Heft viii. Those who wish to see the case as stated by an advocate may refer to Professor Poulton's work, _The Colours of Animals_ (International Scientific Series), lxviii. London, 1890.

[207] _P. Zool. Soc. London_, 1883, p. 372.

[208] _Kosmos_, xix. 1886, p. 353. The Insects alluded to by both these naturalists are now, we believe, placed in the Family Syntomidae (see p. 388).

[209] _Stett. ent. Zeit._ li. 1891, p. 264; and lvi. 1895, p. 234.

[210] For an account of the antennae of butterflies, see Jordan, _Nov. Zool._ v. 1898, pp. 374-415.

[211] Haase first proposed the name Netrocera (_Deutsche ent. Zeit. Lep._ iv. 1891, p. 1) for Hesperiidae, as a division distinct from all other butterflies; Karsch replaced the name in the following year by Grypocera, because _Netrocera_ is the name of a genus.

[212] The literature of butterflies has become extremely extensive. The following works contain information as to general questions: 1, Scudder's _Butterflies of New England_, a beautifully illustrated work completed in 1889, and replete with interesting discussions. 2, Staudinger, Schatz and Röber, _Exotische Tagfalter_, in three folio volumes (Fürth, 1884-1887), with illustrations of exotic butterflies and a detailed sketch of their characters. 3, Enzio Reuter, "Uber die Palpen der Rhopaloceren," in _Acta Soc. Sci. Fenn._ xxii. 1896, treating fully of classification and phylogeny.

[213] _Journal of Entomology_, i. 1862, p. 218: for early instars of South American Nymphalidae see Müller, _Zool. Jahrb. Syst._ i. 1886, p. 417.

[214] This is the subject of Scudder's _Life of a Butterfly_, 1893.

[215] _P. Zool. Soc. London_, 1883, p. 205.

[216] Finn, _J. Asiat. Soc. Bengal_, lxvi. 1896, p. 528; lxvii. 1897, p. 213.

[217] _Trans. Linn. Soc._ xxiii, 1862, p. 495.

[218] _Kosmos_, xix. 1886, p. 355.

[219] _P. ent. Soc. London_, 1879, p. xxix.

[220] Allen's Naturalists' Library, _Butterflies_, i. 1896.

[221] A most unfortunate diversity exists in the generic names applied to these _Vanessa_, as well as in those of many other Lepidoptera.

[222] _Ann. Nat. Hist._ (6), iv. 1889, p. 212.

[223] _P. Zool. Soc. London_, 1892, p. 191.

[224] _Bull. Soc. ent. France_, 1856, pp. c, ci.

[225] Baker, _Tr. ent. Soc. London_, 1887, p. 175, Pl. ix.

[226] _Ann. Soc. ent. France_ (4), vii. 1867, p. 665, Pl. xiii.

[227] _J. Bombay Soc._ ix. 1895, pp. 338-341.

[228] Hopkins, _Phil. Trans._ 186 B, 1895, p. 661.

[229] _Ann. Nat. Hist._ (6), iv. 1889, p. 213. We trust there will not be many more Künstlers, as this beautiful butterfly must certainly become extinct, if the female be really as rare as is supposed.

[230] _Mem. Ac. Washington_, vii. 1895, p. 57.

[231] _Tr. ent. Soc. London_, 1893, p. 97, with Suppl. _op. cit._ 1896, pp. 129 and 567.

[232] _Amer. Natural._ xxix. 1895, p. 1066. See also _Ann. N. York Ac._ viii. 1895, p. 194, and _Ent. Record_, 1897, pp. 136 and 196.

[233] _Handbook of British Lepidoptera_, 1895.

[234] London, 1892. Published under the authority of the Secretary of State for India in Council.

[235] Those numbered 2, 8, 10, 17, 22, 27, 44, and 46 in our arrangement.

[236] For explanatory diagram of the wings, see Fig. 161, I. When the nervuration is obscured by the wing-scales, it may be rendered temporarily visible by the application, with a camel's-hair brush, of a little benzine. The wings may be permanently denuded of their scales by being placed for a short time in Eau de Javelle (hypochlorite of potash).

[237] The genus _Cyphanta_ (one species from India) has nervule 5 of the fore wing proceeding from the lower angle of the cell.

[238] This is a mistake of Sir George Hampson's. It has long been known that the female of _Heterogynis_ does not leave the cocoon (for references see p. 392); the larvae, however, do not live in cases, as those of Psychidae do.

[239] See Westwood, _Tr. Linn. Soc. London_ (2), i. 1877, p. 165, etc.

[240] For habits of some Brazilian Castnia see Seitz, _Ent. Zeit. Stettin_, li. 1890, p. 258.

[241] For pupa see Chapman, _Ent. Rec._ vi. 1895, pp. 286, 288.

[242] _Souvenirs entomologiques_, quatrième série, 1891, pp. 39-46.

[243] _Amer. Natural._ xii. 1878, p. 379.

[244] Cotes, "Wild Silk Insects of India," _Ind. Mus. Notes_, ii. No. 2, 1891, 15 plates.

[245] See on this subject Pérez, _Act. Soc. Bordeaux_, xlvii. 1894, p. 236, etc.

[246] _Berlin. ent. Zeitschr._ xxvii. 1883, p. 9.

[247] _Tr. Linn. Soc._ ser. 2, ii. 1885, p. 421.

[248] _Psyche_, vi. 1893, p. 385.

[249] Bar and Laboulbène, _Ann. Soc. ent. France_, (v.) iii. 1873, p. 300.

[250] _Op cit._ (5), vii. 1877, p. 181; and _Ent. Zeit. Stettin_, xxxix. 1878, p. 221; and xliv. 1883, p. 402.

[251] _Ann. New York Ac._ viii. 1893, p. 48.

[252] _Tr. ent. Soc. London_, n.s. iii. 1854, p. 1.

[253] Dyar says, "We may surmise that it is to present a terrifying appearance toward small enemies." He calls the Insect both _Perophora_ and _Cicinnus_, _melsheimeri_, and states that it belongs [according to the larva] to Tineidae; the appendages he considers to be enormously developed setae. _J. N. York ent. Soc._ iv. 1896, p. 92.

[254] _Tijdsch. Ent._ xxxviii. 1895, p. 56, Pl. 4.

[255] _Ann. New York Ac._ viii. 1893, p. 48.

[256] Weyenbergh, _Tijdschr. Ent._ xvii. 1874, p. 220, Pl. xiii.

[257] Jones, _P. Liverpool Soc._ xxxiii. 1879, p. lxxvii.

[258] _Studies in the Theory of Descent_, part 2, London, 1881.

[259] _Tr. ent. Soc. London_, 1885 and 1886.

[260] _Tijdschr. Ent._ xl. 1897, pp. 27-103, 4 plates.

[261] _Tr. ent. Soc. London_, 1884, p. 351.

[262] _Tr. ent. Soc. London_, 1887, p. 297, Pl. x.

[263] See Poulton, _Tr. ent. Soc. London_, 1886, etc.

[264] _Op. cit._ 1895, p. 399.

[265] _P. ent. Soc. London_, 1880, p. iii.

[266] _Ent. Monthly Mag._ xiii. 1877, p. 231.

[267] _Entomologist_, xxiii. 1890, p. 92.

[268] _Mem. Ac. Washington_, vii. 1895, 290 pp., 49 plates.

[269] _Tr. ent. Soc. London_, 1878, p. 121, Pl. v.

[270] _Op. cit._ 1889, pp. 1-40, 6 plates.

[271] Walsingham, _Op. cit._, 1889. c. p. 21.

[272] _Ent. Zeit. Stettin_, lvi. 1895, p. 233.

[273] _Op. cit._ li. 1890, p. 261.

[274] _Ent. Zeit. Stettin_, li. 1890, p. 263.

[275] For details as to habits, etc., see Rambur, _Ann. Soc. ent. France_, v. 1836, p. 577; and Graslin, _op. cit._ xix. 1850, p. 396.

[276] Monograph of European Psychidae, _Ann. Soc. ent. Belgique_, xxv. 1881, p. 29, etc.

[277] Heylaerts, _op. cit._ p. 55.

[278] _Zool. Anz._ xx. 1897, p. 473. This is probably _Apterona crenulella_, or one of its varieties.

[279] _Bull. U.S. Dep. Agric. Ent._ x. 1887, p. 22.

[280] _Ann. New York Ac._ viii. 1893, p. 54.

[281] Kalender, _Ent. Zeit. Stettin_, xxxv. 1874, p. 203.

[282] _Ent. Tidskr._ xvi. 1895, p. 116.

[283] On larvae of Hepialidae, _J. New York ent. Soc._ iii. 1895, p. 69, Plates III. IV.

[284] Olliff, _Australian Hepialidae, Entomologist_, xxviii. 1895, p. 114.

[285] _Ent. Mag._ xiii. 1876, p. 63; and xxiii. 1886, p. 164.

[286] Weir, _Entomologist_, xiii. 1880, p. 249, plate; King, _Ent. Record_, vii. 1895, p. 111.

[287] Bertkau, _SB. Ver. Rheinland_, xxxvi. 1879, p. 288; and _Arch. Naturg._ xlviii. i. 1882, p. 362.

[288] _Zool. Anz._ iii. 1880, p. 186.

[289] It is much to be regretted that, as in so many other Lepidoptera, no satisfactory agreement as to names has been attained; our British _A. testudo_ is variously styled _Limacodes testudo_ (by Chapman and most naturalists), _Apoda limacodes_ (by Meyrick), or _Apoda avellana_ (Kirby, _Catalogue of Moths_). The family is called either Limacodidae, Apodidae, Cochliopodidae, or Heterogeneidae.

[290] See Chapman, _Tr. ent. Soc. London_, 1894, p. 345, Plate VII., for our British species; for North American forms, Dyar, _Life-histories of the New York Slug-caterpillars_ (in progress, with numerous plates), _J. New York ent. Soc._ iii. etc., 1895.

[291] See Packard, _P. Amer. Phil. Soc._ xxxi. 1893, pp. 83, 108, Plates. (He uses the term Cochliopodidae instead of Limacodidae); also Dyar, as above.

[292] _Insects affecting the Orange_, Washington, 1885, p. 143.

[293] _Tr. ent. Soc. London_, 1894, p. 348.

[294] _Op. cit._ 1876, p. 522; and 1877, p. 433.

[295] _P. Amer. Phil. Soc._ xxxii. 1894, p. 275.

[296] Revision of the Thyrididae; Hampson, _P. Zool. Soc. London_, 1897, p. 603.

[297] _P. ent. Soc. London_, 1891, p. xv.

[298] This moth is known under several generic names—_Psilura_, _Liparis_, _Ocneria_, _Lymantria_; there is now a very extensive literature connected with it. A good general account by Wachtl may be found in _Wien. ent. Zeit._ x. 1891, pp. 149-180, 2 Plates.

[299] Wachtl and Kornauth, _Mitt. forst. Versuchswesen Österreichs_, Heft xvi. 1893.

[300] Crahay, _Ann. Soc. ent. Belgique_, xxxvii. 1893, p. 282.

[301] _Amer. Natural._ xxix. 1895, p. 801.

[302] _Catalogue of Lepidoptera Heterocera_, i. 1892.

[303] _Ann. Soc. ent. France_ (4), iv. 1864, p. 689.

[304] _P. Zool. Soc. London_, 1892, p. 188.

[305] _Tr. ent. Soc. London_, 1892, pp. 53-140; for criticism on the nomenclature, see Rebel, _Ent. Zeit. Stettin_, liii. 1892, p. 247.

[306] See Poulton, _Tr. ent. Soc. London_, 1884, p. 51; _op. cit._ 1892, p. 293; and Bateson, p. 213; Gould, p. 215.

[307] Giraud, _Ann. Soc. ent. France_ (4), v. 1865, p. 105; Fauvel, _l.c._ _Bull._ p. liii.

[308] For a table, see Meyrick, _l.c._

[309] Barrett, "Increasing Melanism in British Geometridae," _Ent. Monthly Mag._ 1895, p. 198.

[310] _P. Zool. Soc. London_, 1892, p. 192.

[311] Although this term is widely used in North America, it is not in use in England, though it may possibly have originated in Scotland. See Slingerland, _Bull. Cornell University Exp. Stat._ 104, 1895, p, 555.

[312] _Fourth Rep. U.S. Ent. Commission_, 1885, p. 3.

[313] _Insect Life_, vi. 1894 p. 6.

[314] See Chapman, _The Genus_ Acronycta _and its Allies_, London, 1893.

[315] _Insects Injurious, etc._, Ed. 1862, Boston, p. 437.

[316] See Westwood, _Tr. Zool. Soc. London_, x. pp. 507, etc., for discussion of this question and for figures; also E. Reuter, _Act. Soc. Sci. Fenn._ xxii. 1896, p. 202.

[317] _Congr. Internat. Zool._ ii. 1892, pt. 2, p. 180.

[318] Ragonot, _Ann. Soc. ent. France_, 1890 and 1891; and Meyrick, _Tr. ent. Soc. London_, 1890, p. 429.

[319] _Ent. Mag._ xii. 1876, p. 210, and xvii. 1881, p. 249.

[320] _Zool. Jahrb. Syst._ vi. 1892, p. 617.

[321] _Nat. Hist. Aquatic Insects_, London, 1895.

[322] For Bibliographic references connected with the divisions of Pyralidae see Ragonot, _Ann. Soc. ent. France_ (6), x. 1890, pp. 458, etc.

[323] Monograph, by Ragonot, in Romanoff, _Mem. Lep._ vii. 1893.

[324] _Ent. Zeit. Stettin_, 1878, p. 230.

[325] Howard, _Insect Life_, vii. 1895, p. 402.

[326] Monograph by Hampson, _P. Zool. Soc. London_, 1895, p. 897-974.

[327] Disqué, _Ent. Zeit. Stettin_, li. 1890, p. 59. Cf. also Rebel, _Zool. Jahrb. Syst._ xii. 1898, p. 3.

[328] Classification; Meyrick, _Tr. ent. Soc. London_, 1886, p. 1.

[329] _P. Linn. Soc. N. S. Wales_ (2), vi. 1881, p. 410.

[330] _Handbook Brit. Lep._ 1895, p. 493.

[331] _Tr. ent. Soc. London_, 1895, p. 495.

[332] _Zool. Anz._ v. 1882. p. 262.

[333] _Ann. Soc. ent. France_ (4), x. 1870, p. 1, pl. vii.

[334] For table of the larvae, according to number of feet and other characters, see Sorhagen, _Berlin. ent. Zeit._ xxvii. 1883, pp. 1-8.

[335] _P. Linn. Soc. N.S. Wales_ (2) vii. 1892, p. 593.

[336] Durrant, _Ent. Mag._, xxxi. 1895, p. 107.

[337] "The Yucca moth and Yucca Pollination," _Rep. Missouri Botanical Garden_, 1892, pp. 99-158.

[338] The maxillary tentacle is considered by Prof. J. B. Smith to be a prolongation of the stipes, cf. _antea_, p. 309; also _Insect Life_, v. 1893, p. 161.

[339] Chapman, _Tr. ent. Soc. London_, 1894, p. 366.

[340] Walter, _Jena. Zeitschr. Naturw._ xviii. 1885. He did not distinguish _Eriocephala_ as a genus, as we have explained on p. 308.

[341] _Amer. Natural._ xxix. 1895, pp. 636 and 803.

[342] Wood, _Ent. Mag._ xxvi. 1890, p. 148.

[343] See Chapman, _Tr. ent. Soc. London_, 1893, p. 255.

[344] Osten Sacken, _Tr. ent. Soc. London_, 1884, p. 501, and _Berlin. ent. Zeitschr._ xxxvii. 1892, p. 423, etc.

[345] Osten Sacken has recently discussed the intermediate conditions, and proposed the name "pseudholoptic" for some of them, _Berlin. ent. Zeitschr._ xli. 1896, p. 367.

[346] Girschner, _Berlin. ent. Zeitschr._ xxxi. 1887, p. 155.

[347] It may be well to remark that this name was formerly applied to all Diptera except Nemocera.

[348] _Zool. Anz._ xvii. 1894, p. 35, and _Ann. Nat. Hist._ (6) xiii. 1894, p. 372; _Zeitschr. wiss. Zool._ lviii. 1895, p. 475.

[349] Cf. Osten Sacken, _Berlin. ent. Zeitschr._ xxxviii. 1893; and Becher, _Wien. ent. Zeit._ i. 1882, p. 49. For an account of the condition, with diagrammatic figures, of the fly emerging from the pupa, cf. Sasatti, _J. Coll. Japan_, i. 1887. p. 34, pl. vi.

[350] It is frequently said that one sex of a single species may be dimorphic in this respect, but we shall subsequently mention (in Blepharoceridae) that this is not yet sufficiently established.

[351] _Fluernes Munddele, Copenhagen_, 1881, 91 pp. 6 plates; _Ent. Tidskr._ i. 1879, p. 150; Becher having given (_Denk. Ak. Wien._ xlv. 1882, p. 123) an interpretation different from that of Meinert, this author set forth his general views in _Zool. Anz._ v. 1882, pp. 570 and 599.

[352] The reader should not suppose that there are only two views as to the Dipterous mouth, for actually there are several; our object is here only to give a general idea of the subject.

[353] _Tr. Linn. Soc. London_ (2) v. 1892, p. 271.

[354] _Tr. ent. Soc. London_, 1884, p. 497.

[355] Osten Sacken, although making use of the terms tegula and antitegula, suggested the propriety of using squama and antisquama, as we have done.

[356] _Zeitschr. wiss. Zool._ li. 1891, p. 55.

[357] Brandt, _Horae Soc. ent. Ross._ xiv. 1878, p. vii.; xv. 1879, p. 20. Brauer, _Denk. Ak. Wien_, xlvii. 1883, pp. 12-16. Künckel, _C.R. Ac. Paris_, lxxxix. 1879, p. 491.

[358] _Blow-fly_, 1895: in two vols. For Anatomy of _Volucella_, see Künckel d'Herculais, _Recherches sur l'org. des Volucelles, Paris_, 1875 and 1881.

[359] _Tijdschr. Ent._ xxxviii. 1895, pp. 65-100.

[360] _Denk. Ak. Wien_, xlvii. 1883, pp. 1-100, pls. i.-v.

[361] Since our brief and imperfect sketch of metamorphosis appeared in Vol. V. of this series, Packard has treated the subject more fully in his _Text-book of Entomology_, New York, 1898; and Pratt has summarised the state of knowledge as to imaginal discs in _Psyche_, viii. 1897, p. 15, etc.

[362] Monograph of Oestridae, _Verh. Ges. Wien_, 1863, and other papers _op. cit._ 1864, 1867, 1869; also _Denk. Ak. Wien_, xlii. 1880, xlvii. 1883.

[363] Becher, _Wien. Ent. Zeit._ i. 1882, p. 49; for observation on connecting forms see Brauer, _Verh. Ges. Wien_, xl. 1890, p. 272.

[364] The palpi are said to be of only one segment in some genera of Cecidomyiidae. The Cecidomyiidae are easily distinguished by the minute size—body not more than a line long—and by there not being more than six nervules at the periphery of the wing. _Aëdes_ (Culicidae) has also short palpi.

[365] It is said by Schiner that in the anomalous genus _Nemestrina_ the palpi are of three segments.

[366] For tables of the families of flies the student may refer to Loew, _Smithson-Misc. Coll._ vi. Art. i. 1862; to Brauer, _Denk. Ak. Wien_, xlii. 1880, p. 110 (Orthorrhapha only); to Williston, _Manual of N. American Diptera_, 1896; to Schiner, _Fauna austriaca, Diptera, Vienna_, 1860, etc.

[367] _Berlin. ent. Zeitschr._ xxxvii. 1892, p. 365, and xli. 1897, p. 365.

[368] _Tr. Amer. ent. Soc._ iii. 1871, p. 345.

[369] _Bull. Soc. ent. France_, 1893, p. lxxx.

[370] _Naturhist. Tidskr._ (3) viii. 1874, p. 34, pl. xii.

[371] _Ann. Soc. ent. France_ (2) vii. 1849, p. 346.

[372] _Trans. New Zealand Inst._ xxiii. 1890, p. 48.

[373] Osten Sacken, _Berlin. ent. Zeitschr._ xxxvii. 1892, p. 442; and Perris, _Ann. Soc. ent. France_ (2) vii. 1849, p. 202.

[374] See Guérin-Méneville, _Ann. Soc. ent. France_ (2) iv. 1846; _Bull._ p. 8; and Nowicki, _Verh. Ges. Wien_, xvii. 1867, _SB._ p. 23.

[375] For details as to the family cf. Osten Sacken, _Berlin. ent. Zeitschr._ xl. 1895, p. 148; and for the larvae F. Müller, _Arch. Mus. Rio-Jan._ iv. 1881, p. 47. The name "Liponeuridae" was formerly applied by some authorities to this family, but it is now generally recognised that Blepharoceridae is more legitimate.

[376] _Berlin. ent. Zeit._ xxv. 1881, p. 61; and cf. Brauer, _Wien. ent. Zeit._ i. 1882, p. 1.

[377] _Natural History of Aquatic Insects_, London, 1895, chap. ii.

[378] _Tr. Linn. Soc. Lond._ (2) ii. 1884, p. 367.

[379] For an extremely interesting account of _Chironomus_ refer to Miall's book, already cited, and, for the larva, to the valuable work of Meinert on Eucephalous larvae of Diptera, _Danske Selsk. Skr._ (6) iii. 1886, p. 436.

[380] _Ann. Nat. Hist._ (4) viii. 1871, p. 31.

[381] _Ibid._ (6) xv. 1895, p. 133.

[382] For metamorphoses of aquatic species of _Ceratopogon_, see Miall and Meinert, already quoted: for examples of the terrestrial species, and their illustrations, refer to Mik, _Wien. ent. Zeit._ vii. 1888, p. 183.

[383] Monograph, Eaton, _Ent. Mag._ xxix. and xxx. 1893, 1894: supplement _op. cit._ 1896, etc.

[384] _Tr. ent. Soc. London_, 1895, p. 141.

[385] _Tr. ent. Soc. London_, 1895, p. 479.

[386] _A Naturalist's Sojourn in Jamaica_, London, 1853, p. 284.

[387] _Bull. Illinois Lab._, iv. 1895, p. 193.

[388] Miall's _Aquatic Insects_, 1895, p. 174.

[389] "Studies," etc., _Berlin. ent. Zeitschr._ xxxi. 1887.

[390] _Tr. ent. Soc. London_, 1897, p. 362.

[391] _Tr. ent. Soc. London_, 1897, pp. 343-361.

[392] _Acta Univ. Lund._ xxxiii. (2) No. 7, 1897.

[393] "Studies," etc., _Berlin. ent. Zeitschr._ xxx. 1886, p. 153.

[394] Osten Sacken, _Berlin. ent. Zeitschr._ xxxvii. 1892, p. 450.

[395] _Entomologist_, xiv. 1881, p. 287. This observation has never, we believe, been confirmed.

[396] _Ann. Soc. ent. France_ (2) v. 1847, p. 46.

[397] Perris, in _Ann. Soc. ent. France_ (2) v. 1847, p. 37, pl. i.

[398] _Ann. Soc. ent. France_ (5) i. 1871, _Bull._ p. lxvii.

[399] _Rep. Dep. Agric. Ent. Washington_, 1886, p. 492.

[400] Cf. Réaumur, _Mem._ v. 1740, p. 21; and Perris, _Ann. Soc. ent. France_ (4) x. 1870, p. 190.

[401] _Verh. Ges. Wien_, xxx. 1880, p. 343.

[402] _Arch. Naturges._ xli. i. 1875, p. 48.

[403] _Bull. Illinois Lab._ iv. 1895.

[404] _Ent. Mag._ xxiii. 1886, p. 51.

[405] _Ann. Soc. ent. France_, ii. 1833, p. 492.

[406] _Wien. ent. Zeit._ ii. 1883, pp. 11 and 24, pl. i.

[407] _Ent. Mag._ xiv. 1878, p. 196.

[408] For figures, etc., cf. Westwood, _Tr. ent. Soc. London_, 1876, p. 507, pls. v. vi.

[409] _Verh. Ges. Wien_, xix. 1869, p. 737, pl. xiii.

[410] _Tr. ent. Soc. London_ (3) i. 1862, p. 338, pl. xi.

[411] _Verh. Ges. Wien_, xix. 1869, p. 941.

[412] _Ann. Soc. ent. France_ (4) x. 1870, p. 221.

[413] _SB. Ak. Wien_, xci. 1885, p. 392.

[414] _Ent. Mag._ xiv. 1877, p. 226; for a discussion of the subject see Mik, _Wien. ent. Zeit._ xiii. 1894, p. 273.

[415] _Amer. Natural._ xxviii. 1894, p. 35.

[416] Perris, _Ann. Soc. ent. France_ (4) x. 1870, p. 321, pl. 4; and Laboulbène, _op. cit._ (5) iii. 1873, p. 50, pl. v.

[417] Perris, _Ann. Soc. ent. France_ (4) x. 1870, p. 354.

[418] _Ent. Meddelelser_, ii. 1890, p. 213.

[419] Frauenfeld, _Verh. Ges. Wien_, xx. p. 37, pl. iii.

[420] For monograph of Pipunculidae, see Becker, _Berlin. ent. Zeitschr._ xlii. 1897, pp. 25-100.

[421] _Ofv. Ak. Forh._ xi. 1854, p. 302, pl. v., since confirmed by others, see Giard, _C.R. Ac. Sci._ cix. 1889, pp. 79 and 708.

[422] _Natural History of Aquatic Insects_, 1895, p. 198.

[423] _Ent. Zeit. Stettin_, vi. 1845, p. 384, pl. i.

[424] _Ann. Soc. ent. France_ (6) iii. 1883, p. 23, pl. i.

[425] _Ent. Nachr._ xviii. 1892, p. 13.

[426] _Ann. Soc. ent. France_ (4) x. 1870, p. 330.

[427] See on this difficult subject, Becher, _Wien. ent. Zeit._ i. 1882, p. 49.

[428] _Loudon's Magazine_, v. 1832, p. 302; _P. ent. Soc. London_, 1871, p. x.

[429] Baron von Osten Sacken informs the writer that this statement has since been withdrawn by Portschinsky as being erroneous.

[430] _Ent. Amer._ iii. 1887, p. 126.

[431] _J. Coll. Japan_, i. 1886, pp. 1-46, plates i.-vi.

[432] _Souvenirs entomologiques_, 1879, pp. 246-254.

[433] A list of the Insects known to be attacked by Dipterous parasites has been given by Brauer and Bergenstamm, _Denk. Ak. Wien_, lxi. 1895.

[434] _Berlin. ent. Zeit._ xxx. 1886, p. 135.

[435] _Berlin. ent. Zeitschr._ xxxi. 1887, p. 17.

[436] _Biol. Centralbl._ vii. 1887, p. 521.

[437] For an account of the habits of this fly, see Kirk, _J. Linn. Soc._ viii. 1865, pp. 149-156; and for a bibliographic list, Wulp, _Tijdschr. Ent._ xxvii. 1884, p. xci. and pp. 143-150.

[438] _Preliminary Report on the Tse-tse Fly Disease_, 1895.

[439] _P. Liverpool Soc._ xxxiii. 1878, p. 13, note.

[440] We may specially mention the monograph of Oestridae, published in 1863 by the _K. k. Zool.-Bot. Ges. Wien_, and supplements in _Wien. ent. Zeit._ v. vi. 1886, 1887; these include copious bibliographic lists.

[441] Riley, _Insect Life_, iv. 1892, p. 302.

[442] See Blanchard, _Ann. Soc. ent. France_ (7) ii. 1892, pp. 109, 154.

[443] See Bigot, _Ann. Soc. ent. France_ (6) ii. 1882, p. 21, Brauer, _Monograph_, 1863, p. 51, and _Wien. ent. Zeit._ vi. 1887, p. 75.

[444] _Arch. Naturgesch_. lviii. i. 1892, pp. 287-322, pls. xv. xvi.

[445] Stein, _Deutsche ent. Zeit._ xxi. 1877, p. 297.

[446] _Abh. Ges. Halle_, iv. 1858, p. 145.

[447] _Arch. Naturgesch._ lix. i. 1893, p. 151.

[448] _SB. Ak. Wien._ cv. 1896, _Abtheil._ i. p. 400.

[449] _Arch. Naturges._ lviii. i. 1892, p. 287.

[450] _Horae Soc. ent. Ross._ ii. 1863, p. 90.

[451] _Tr. ent. Soc. London_, 1881, p. 360.

[452] The best general description of the external anatomy of the flea is to be found in Taschenberg, _Die Flöhe_, 1880. The morphology is better elucidated, though still incompletely, in Wagner's valuable "Aphanipterologische Studien," _Horae Soc. ent. Ross._ xxiii. 1889, pp. 199-260, 5 plates, and _op. cit._ xxxi. 1897, pp. 555-594, 3 plates. Cf. also N. C. Rothschild, _Nov. Zool._ v. 1898, pp. 533-544, 3 plates.

[453] Howard, _Bull. Dep. Agric. Ent._ N.S. No. 4, 1896.

[454] Schimkewitsch, _Zool. Anz._ vii. 1884, p. 673.

[455] _P. Boston Soc._ xxvi. 1894, pp. 312-355.

[456] _Monographie der Ordnung Thysanoptera_, Königgrätz, 4to, 1895.

[457] _Bull. Essex Inst._ xxii. 1890, p. 24; also _Amer. Natural._ xxx. 1896, p. 591.

[458] Jordan in an interesting paper, _Zeitschr. wiss. Zool._ xlvii. 1888, p. 573, says that in the division "Terebrantia" there are only three pairs of stigmata.

[459] _Insect Life_, i. 1888, p. 138.

[460] See Lindeman, _Bull. Soc. Moscou_, lxii. 1886, No. 2, p. 296, and Uzel, _Mon._ 1895, pp. 397, 398.

[461] _Entomological Magazine_, iii. 1836, p. 439, and iv. 1837, p. 144.

[462] _Zeitschr. wiss. Zool._ xvi. 1866, p. 389.

[463] _Arb. Inst. Wien_. iv. 1882, p. 415.

[464] _Tr. Amer. Phil. Soc._ xix. 1896, p. 176.

[465] _P. ent. soc. Washington_, iii. 1895, p. 241.

[466] _Ent. Nachr._ xxii. 1896, p. 173.

[467] _Zool. Anz._ 1897, No. 527, p. 73.

[468] _Arch. Anat. Physiol._ 1874, p. 313, and 1875, p. 309.

[469] For the structure and development of the Hemipterous trophi, see Mayer, _Arch. Anat. Physiol._ 1874 and 1875; Mecznikow, _Zeitschr. wiss. Zool._ xvi. 1866, p. 389; Geise, _Arch. Naturgesch._ xlix. 1, 1883, p. 315; Wedde, _op. cit._ li. 1, 1885, p. 113; Mark, _Arch. mikr. Anat._ xiii. 1877, p. 31: Smith, _Tr. Amer. Phil. Soc._ xix. 1896, p. 176.

[470] _Ent. Nachr._ xix. 1893, p. 369.

[471] _Naturhist. Tidskr._ (3) vi. 1896; translated in _Ann. N. Hist._ (4), vi. 1870, p. 225.

[472] _Ent. Zeit. Stettin_, xxvii. 1866, p. 321.

[473] _Ent. Nachr_. xix. 1893, p. 375.

[474] On this subject, see Reuter, _Ann. Soc. ent. France_ (5) v. 1875, p. 225.

[475] _Ann. Soc. ent. France_ (4) vii. 1867, p. 45.

[476] The chief work on the internal anatomy of Hemiptera is still Dufour's _Recherches anatomiques et physiologiques sur les Hémiptères, Mem. Savans Étrangers_, Paris, iv. 1833, p. 129.

[477] Künckel, _Ann. Soc. ent. France_ (4) vii. 1867, p, 45, and _C.R. Ac. Paris_, cxx. 1895, p. 1002.

[478] In Slingerland's _Cornell Univ. Bull._ No. 58, 1893, p. 222.

[479] _SB. Ak. Wien._ xci. 1 Abth., 1885, p. 275.

[480] _Les Insectes fossiles, etc._, 1894, p. 452.

[481] _Ann. Nat. Hist._ (4) vi. 1870, p. 225.

[482] A table of the families is given by Ashmead, but does not work out quite satisfactorily, _Entom. Americana_, iv. 1888, p. 65; a brief table of the characters of the British families is given by Saunders, _Hemiptera-Heteroptera of the British Islands_, 1892, p. 12.

[483] Those who wish to see tables of the families are referred to Ashmead, _loc. cit._; to Pascoe, _Ann. Nat. Hist._ (5) ix. 1882, p. 424; to Stål's _Hemiptera Africana_, vol. iv. 1866; and for the families found in Britain to Edwards, _Hemiptera-Homoptera of the British Islands_. For a discussion in Danish on the value of the characters used, cf. Hansen, _Ent. Tidskr._ xi. 1890, pp. 19-76.

[484] _Ent. Mag._ vii. 1870, p. 53.

[485] _Insect Life_, i. 1889, p. 234.

[486] _C.R. Ac. Sci. Paris_, cxviii. 1894, p. 1282.

[487] _Verh. Ges. Wien._ iii. 1858, p. 157.

[488] _Ent. Mag._ xxix. 1893, p. 227.

[489] _Wien. ent. Zeit._ xi. 1892, p. 169.

[490] _Monograph of Phymatidae_: Handlirsch, _Ann. Hofmus. Wien_, xii. 1897, p. 127.

[491] _Ent. Zeit. Stettin_, li. 1890, p. 281.

[492] _Naturalist's Voyage_, ed. 1884, p. 330; chap. xv.

[493] _Thesaurus ent. Oxoniensis_, 1874, p. 197.

[494] _Ind. Mus. Notes_, iii. No. 5, 1894, p. 53.

[495] Ferrari, Monograph of _Nepa, Ann. Hofmus. Wien_, iii. 1888, p. 171.

[496] _Bull. Soc. Philomat._ (8) v. 1893, p. 57. There is some diversity of opinion as to the respiratory orifices, and some authorities say that thoracic stigmata exist even in the imago.

[497] _Acta Ac. German._ li. 1887, p. 224, and _Zeitschr. wiss. Zool._ xliii. 1886, p. 537.

[498] Korschelt, _Acta._ _t.c._ p. 245. Compare the remarks we have made on p. 559 as to the peculiarities of eggs of many other Hemiptera.

[499] _Bull. Mus. Paris_, 1896, p. 238.

[500] See Carpenter, _Irish Naturalist_, iv. 1895, p. 59.

[501] See remarks on pp. 543, 544.

[502] We must refer those who may wish for further information as to this complex and difficult question to the writings of the late Professor Riley, especially to Bulletin No. 8, 1885, U.S. Department of Agriculture, division of entomology; and to the more recent report by Marlatt, _Bull. Dep. Agric. Ent._, N.S. No. 14, 1898.

[503] Some entomologists consider that this "railway-whistle" note is the result of the combined efforts of several individuals. Cf. Mathew, _Ent. Mag._ xi. 1875, p. 175.

[504] It is unnecessary to say that the poet was not Sappho, but one of the baser sex, named Xenarchus.

[505] Swinton claims that one of the membranes in the vocal apparatus is an auditory organ; if so, the male would be deafened by his own noise, while the females, not possessing the organ, should not hear the song.

[506] _P. ent. Soc. London_, 1883, p. 20.

[507] A considerable variety of these extraordinary creatures are figured in _Biol. Centr. Amer. Rhynch. Homopt._ ii.

[508] Riley, _P. ent. Soc. Washington_, iii. 1895, p. 88. For the younger stages of _Membracis foliata_, see _Tijdschr. Ent._ (2) iv. 1869, pl. viii.

[509] _Tr. ent. Soc. London_, 1886, p. 329.

[510] _Verh. z.-b. Ges. Wien_, xxvi. 1876, p. 167.

[511] _Cornell Univ. Agric. exp. station Bulletin_, 44, 1892, and _Bull._ 108, 1896.

[512] _Zeitschr. wiss. Zool._ xlii. 1885, pp. 569-638.

[513] _Zeitschr. Naturw._ (2) xii. 1875, p. 438.

[514] Réaumur, Mém. iii. 1737, _Dixiéme Mémoire_.

[515] _P. ent. soc. Washington_, iv. 1897, p. 66.

[516] For list see Scott, _Ent. Mag._ xviii. 1882, p. 253.

[517] There is some doubt on this point, as the earlier observers seem to have supposed that a winged individual appearing in a generation chiefly apterous was _ipso facto_, a male; it seems, however, to be certain that perfect winged males appear in some species in generations producing no perfect sexual females. Speaking generally, the course of events seems to be that in summer there exist only wingless and winged parthenogenetic females, and that the sexually perfect forms appear for the first time in autumn.

[518] _Mitt. Schweiz. ent. Ges._ iv. 1876, p. 529.

[519] The term pseudovum is applied, as a matter of convenience, to the earlier condition of the viviparously-produced form, and the term pseudovarium to the ovary producing it.

[520] Balbiani, _Ann. Sci. Nat. Zool._ (5) xi. 1869, p. 29. For concise recent remarks on the early embryonic states, see Lemoine, _Bull. Soc. ent. France_, 1893, p. lxxxix.

[521] _Acta Ac. German._ xxxiii. 1869, No. 2, p. 81.

[522] _Seventeenth Rep. Insects Illinois_, 1891, p. 66.

[523] Kessler, _Acta Ac. German._ li. 1887, pp. 152, 153.

[524] In connection with this the absence of a functional mouth in the imago state of numerous Lepidoptera, and of Oestrid Diptera, should not be forgotten.

[525] _Horae Soc. ent. Ross._ xxiv. 1890. p. 386.

[526] _Ent. Zeit. Stettin_, xxxvi. 1875, p. 368.

[527] _Zool. Anz._ xv. 1892, p. 220.

[528] _Arb. Inst. Wien_, iv. 1882, Heft iii. p. 397; see on this organ also Mordwilko, _Zool. Anz._ xviii. 1895, p. 357.

[529] _Biol. Centralbl._ xi. 1891, p. 193.

[530] See, _inter alia_, Webster, _J. New York ent. Soc._ i. 1893, p. 119.

[531] _J. New York Ent. Soc._ i. 1893, p. 120. See also as to knowledge on the part of ants, Forbes, _Eighteenth Rep. Insects Illinois_, 1894, pp. 66, etc.

[532] Monograph by Buckton, _Ray Society_, 4 vols. 1879-1883.

[533] _Tr. New Zealand Inst._ xxviii. 1895.

[534] A catalogue of Coccidae has recently been published by Mr. T. D. A. Cockerell in _Bull. Illinois Lab._ iv. 1896, pp. 318-339.

[535] Signoret's papers are to be found in eighteen parts in _Ann. Soc. ent. France_, 1868 to 1876: the most considerable subsequent systematic papers are those by Maskell in the _Transactions of the New Zealand Institute_ from 1878 to the present time.

[536] _Coccidae of Ceylon_, pt. 1, 1896, p. 16.

[537] _C. R. Ac. Sci. Paris_, civ. 1887, p. 449.

[538] _Arch. Naturgesch._ li. i. 1885, p. 169.

[539] _Zeitschr. wiss. Zool._ xliii. 1886, p. 156.

[540] For summary as to our present knowledge of this curious condition of Insect life, see Mayet, _Ann. Soc. ent. France_, 1896, p. 419.

[541] For additional information as to useful Coccidae, see Blanchard, _Bull. Soc. Zool. France_, viii. 1883, p. 217.

[542] Rubsaamen's paper on these Insects gives references to most of the previous literature, _Berlin. ent. Zeitschr._ xxxix. 1894, p. 199.

[543] _Ent. Meddel._ iii. 1891, p. 82.

[544] Cf. Graber, _Zeitschr. wiss. Zool._ xxii. 1872, p. 165, and Landois in the same Journal, xiv. 1864, p. 24.

[545] _Ann. Nat. History_ (3), xvii. 1866, p. 213.

[546] _N. York Ent. Soc._ vii. March 1899, p. 45.