CHAPTER XIII
LETTERS TO COLONEL COUSSMAKER AND MR. ROBERT SERVICE
Surface Caterpillars—Leopard and Puss Moths—“Hill-Grubs” of the Antler Moth.
The letters in this the first chapter of correspondence (dealing with a number of moths, the caterpillars of which are destructive to vegetation), were written while Miss Ormerod was resident at Isleworth, and after she had issued seven of her Annual Reports. Apart from the Entomology discussed, the letters show how ready she was to recognise and to commend the meritorious scientific work of others.
_To Colonel Coussmaker, Westwood, near Guildford._
DUNSTER LODGE, SPRING GROVE, ISLEWORTH, _August 1, 1885_.
DEAR SIR,—Perhaps the best way I can reply to your inquiry about the coloured sheets is to enclose the short description, on the wrapper of one of my reports.[45]
I should mention, though, that they are the property of the Royal Agricultural Society; I only drew them. The insects are drawn greatly magnified, with a view to hanging the sheets on walls of schools. The history, and the simplest means of prevention are given in the very plainest words I could find.
Have you my current report? It contains a good deal on that great pest the Ox warble fly (fig. 5)—contributed by practical men—cattle owners, veterinary observers and the like. I would, with the greatest pleasure, ask your acceptance of a copy if you would permit me to do so. If you have studied its habits in India, I should greatly like to be in communication with you on the subject. The Colonial Company procured me a few estimates of damage to hides—which were of much service as showing comparative amount of injury in different parts of the globe, but I much want to find whether in India the larva is found to penetrate below the subcutaneous tissue into the flesh. I am aware from one of my contributors connected with inspecting army supplies in India, that at one time meat for the troops was apt to be so damaged from what he considered to be this attack, that it was to some extent useless. The locality was not far from Kurrachee. If you, as a student of insect life, could give me any information on this point, I should be thankful for the addition to the notes I am still collecting.
_August 4, 1885._
Many thanks to you for so kindly taking the trouble to write about the injury to flesh possibly caused by the Warble maggot; it would be of great service to know about it. Doubtless your care of your cattle had a great deal to do with their being free from injury—if we could but get even the moderate amount of care applied which is needed to put on a dressing when attack is seen it would make an enormous difference.
The Dart or Turnip moth caterpillar is doing damage now—and I do not believe there is a better remedy than scraping out the grubs, but this is very troublesome till they are larger. I see in a report on the “Cutworms,” as they call these creatures in the U.S.A., that there is very much less injury from them on ground which has been well salted. It is thought that the salt drawn up into the plant makes it distasteful to the caterpillars. I do not know how this may be, but in a district of the Eastern Counties reported from last year—where previously they had been quite set against anything “artificial”—they were finding the turnips on salted lands answered very much the best. I should much like to try the effect of watering with salt and water, at a safe strength, but from my own garden being so perpetually used for trial ground it is getting free of regular pests. I have found watering with soft soap and a little mineral oil (pp. 66-67, eighth report, 1884), act well on these caterpillars. The application appeared to paralyse the creature so that it could not get away from the poisonous effects of the mixture, which is a very important point.
I found this mixture act well on Cabbage green fly, and if you should try it I shall be very much obliged for any observation. The great point is to mix the ingredients at boiling heat. I would try whether the strength noted was safe for any special plant. I rather think it is for cabbage, but certainly not for young leafage of roses. I shall be very glad if I can be of any help in the matter.
[Illustration:
(_a_) 1, Turnip moth; 2, caterpillar. ]
[Illustration:
(_b_) 1, Heart-and-dart moth; 2, caterpillar; 3, chrysalis in earth-cell.
FIG. 1.—SURFACE CATERPILLARS: OF THE TURNIP OR DART MOTH, _AGROTIS SEGETUM_, OCHSENHEIMER, AND OF THE HEART-AND-DART MOTH, _AGROTIS EXCLAMATIONIS_, LINN. ]
TORRINGTON HOUSE, ST. ALBANS, _January 26, 1888_.
Many thanks for your note received this morning. I shall hope to add some of it to my Turnip Caterpillars paper, which is not yet gone to press. Thank you for the offer of the specimens, but I do not quite see my way to showing live ones yet. My lecture [at the London Farmers’ Club] is a terribly anxious prospect to myself, but I can but do my best, and I am endeavouring with the utmost care to form something that may be acceptable, but I am sure you will believe me that to address such a skilled audience is rather anxious work. I should much like to lay before the members of the Club some ideas for their consideration as to how some reasonable amount of plain serviceable information might be got abroad. I do not believe in all this lecturing, examining and talking of classification. To my thinking it is beginning at the wrong end, and that the learners need first to make sure of their facts in the field and classify them when they have got them, if they do it at all.
[Illustration:
Female, head of male, and caterpillar.
FIG. 2.—WOOD LEOPARD MOTH, _ZEUZERA ÆSCULI_, LINN. ]
_February 17, 1890._
I have examined your caterpillars carefully, and I find that of the oak stem to correspond exactly with the larva of the Wood leopard moth, the _Zeuzera æsculi_. This is commonly found in (or at least it is usually sent me from) wood of fruit trees, but it attacks oak as well as forest trees of various kinds. Your specimen has also one of the characteristic habits of ejecting brown fluid from its mouth on disturbance. I think you have my “Manual,” and there you would find a figure of the moth and larva. Your specimen is rather full coloured, but they vary greatly in this respect.
Your other caterpillar is a Lepidopterous larva, but I cannot name it with certainty. It is quite possible that it is the larva of the “Hornet Clearwing,” the _Trochilium_ (= _Sesia_) _bembeciforme_, but I have never seen a specimen, although the attack is said to be common, especially to _Salix caprea_. The attack is stated to be mostly in the lower part of the stem. I think that you very likely have Loudon’s “Arboretum” in your library, and if so you would find some good notes and fair figures of the hornet-like moth and its larva and pupa _in situ_ in the wood at pp. 1481 and 1482, vol. iii. The larva is nearly dead now, so that the form is altered, but I do not see any reason against it being this kind; still I cannot say it is.
I have a very curious report of much damage attributed to Puss moth caterpillars at a locality in Lincolnshire, and am waiting with much interest for specimens to see what the cause can be. I rather expect it will be rabbits!
Yours very truly, ELEANOR A. ORMEROD.
[Illustration:
Male and caterpillar (life size).
FIG. 3.—PUSS MOTH, _DICRANURA VINULA_, LINN. ]
[The following notes by Mr. Robert Service[46] are explanatory of subjoined correspondence.
“THE ‘HILL-GRUB’ (the caterpillar of the Antler moth, _Charæas graminis_). Sheep-farmers are threatened with another plague. The ‘hill-grub’ has often done considerable damage to the upland grass-lands, notably in the years from 1830 to 1835. Just now complaints are rife from farms in many parts of the wide districts ravaged by the Voles[47] (in 1891-92-93). As usual the farmers look on these ‘hill-grubs’ as very sudden arrivals, but this is not the case, for last autumn the moths which these larvæ produce were in extraordinary swarms, and far in advance of their normal numbers. I remember noting at the end of last September when coming down from the neighbourhood of Loch Dungeon one evening in the twilight, how unusually abundant the Antler moths were flying. The evening was mild and very moist, and just as we got on to the level ground at the outside of a moss of perhaps six acres in extent, we found Antler moths flying in countless myriads in every direction. The time was 6.40, and there was still enough of the gloaming left to see the moths quite distinctly on every side, flying just below the level of the grass-seed heads.
“On August 23rd I happened to be going across the farm of Townhead, in Closeburn parish, Dumfriesshire, and about 10.10 a.m. the Antler moths appeared in myriads. Thousands upon thousands of them were flying in all directions, most of them just amongst and over the flowering heads of the spret, _Juncus articulatus_; but many were flying higher in the air, and some mounted up out of sight. It was a wonderful scene, and one that I would not have cared to miss. The effect was altogether different to that presented by the evening flight I saw near Loch Dungeon in the previous autumn.
[Illustration:
FIG. 4.—ANTLER OR GRASS MOTH, _CHARÆAS GRAMINIS_, AND CATERPILLARS. ]
“A party of gentlemen fishing from near the Holm of Dalquhairn for some five or six miles down the Ken found all the trout they caught perfectly crammed with these ‘hill-grub’ caterpillars. Old shepherds will tell of times when they were so numerous that after sudden thundershowers the sheep-drains have been completely dammed up with their bodies. The moth deposits its eggs, which produce larvæ that descend to and feed mostly about the roots of grasses during the autumn and early winter. After hybernation they commence in March and April to feed again with redoubled energy, and they turn to pupæ at the end of June and during July, producing the moths again in a few weeks (the perfect insect flies during August and September). Thus their cycle of existence in these various stages extends the whole year round. Their worst natural enemy is the common rook at the season when these birds betake themselves and their young broods to the hills, and I have reason to believe that many other birds devour them. The blackheaded gull, _Larus ridibundus_, and the common gull, _L. canus_, are very fond of the larvæ. Curlews take a good many, golden plovers and lapwings pick them up in numbers. Cuckoos also feed upon them, and I have found the stomachs of snow buntings, shot on the hills at midwinter, filled with these grubs” (R. S.).
* * * * *
Miss Ormerod says: “The caterpillars, when full grown, are about an inch or rather more long, with brown head, and the body of a deep bronze colour, exceedingly shiny on the back and on the upper part of the sides. The bronze colour is divided lengthwise by three pale lines, the back and side stripes meeting or almost meeting above the tail, and another narrower pale stripe or line runs lower down along each side.”]
_To Robert Service, Esq., Maxwelltown, Dumfries._
TORRINGTON HOUSE, ST. ALBANS, _August 1, 1894._
DEAR SIR,—It is many years since you gave me any of your good observations, but indeed I would gladly have profited by them, and it was only lately that I knew you were continuing them. Perhaps Mr. Bailey, the editor,[48] may have mentioned to you that I was so struck with the paper which he sent me, in which you mention _C. graminis_, that interpreting the _nom de plume_ (“Mabie Moss”) literally, I wrote to him expressing my admiration and asking if I might be put in communication with the writer; and now may I prefer the request to yourself that, if you please, you will kindly tell me anything you are inclined to favour me with about this recent outbreak of the _C. graminis_. Would it not be of great interest if we could make out something more about the parasites? There are, firstly, the threadworms—_Mermis_. Do you chance to have identified them? I have got no further than the specialist to whom I sent specimens, thinking they were most likely _Mermis albicans_—but this he was going to investigate. Then there is the bacterian infestation—the “flacherie,”[49] as they call it in silk-worms. This seems to me of great practical interest; and, thirdly, the larval parasitism of the _C. graminis_ larvæ. I had so exceedingly few specimens that I could not work up the matter, but, whilst one cocoon sent to me appeared to be that of an Ichneumon, the only large larva which I found certainly in many respects resembled that of a _Tachina_ fly. I should greatly like, if agreeable to yourself, to hear from you again on entomological matters. Besides the pleasure, it is a great advantage to me to have contributions of skilled and experienced information, and I would indeed most scrupulously acknowledge to whom I was indebted.
_August 3, 1894._
I am much obliged to you for taking the trouble to send the morsels of _C. graminis_ caterpillars. As you say, I am afraid we could hardly get results from them, but still with bacteria presence I do not know but dried bits may show something when moistened, so I am keeping them for the present. That enormous appearance of the imagos must have been a wonderful sight; I should have liked to see it—and what (I wonder) will be the result?
Pretty surely I suppose there will be egg-laying and a consequent presence of larvæ? But if your convenience allowed you to inspect say two months hence, would it not be very interesting to ascertain—absolutely make sure—whether there is a presence of the “hill-grubs” or whether the parasitism of their parents has been transmitted, to the weakening or destruction of their descendants? If we found no grubs, nor grubs with “flacherie” present, what a very interesting discovery this would be!
_September 14, 1894._
I am writing a few lines at once on receipt of your letter, first to thank you for your geographical note, which helps me very much. [These attacks of “hill-grubs” were more or less general over the hill country of Kirkcudbrightshire and over the adjacent sheep-farms in Ayrshire, the Dumfriesshire hills, and the contiguous sheep-farm districts in Lanarkshire, Peebles, Selkirk, and Roxburgh. Seven counties were affected to my knowledge. R.S.] What a widespread outburst this has been! But I also write to beg you not to suppose for one minute that I see any reason to doubt what we have had laid down for such a length of time about date of hatching of larvæ of _C. graminis_. Mr. Wm. Buckler[50] “lumped” his observations of this and two other species, and it seems to me that what happened to caterpillars, which I gather he observed in captivity, in no way militates against correctness of other people’s out-of-door observations.
With many thanks for all the information you give me.
_November 20, 1894._
I am very much obliged to you for the very interesting note you have let me have about these dipterous parasites[51] of the _C. graminis_. How fortunate you have been to secure them, and in such good order too! As you have been kind enough to give me two of your specimens, I think I will presently send one of them to Mr. Meade, of Bradford. I am sure he would value it very much, and would doubtless identify it, which would be a help to me, for as you know I do not like to rest without verification on my own dipterous identifications. You would not mind about this part, as doubtless if you have not yourself identified, Mr. Percy H. Grimshaw, Museum of Science and Art, Edinburgh, would see to it (pp. 149, 185).
Do you ever come across the so-called “Turnip Mud-beetle,” _Helophorus rugosus_, in your country? I had the beetle some years ago, as doing harm to turnip leafage, but we could not find the larva. Lately we found a larva doing a deal of mischief in the same neighbourhood by burrowing galleries in the top of turnips, and it struck me we might have what we wanted to complete the history. So I sent it to Canon Fowler, and he identified as beyond doubt _Helophorus_ and being found where _H. r._ resorts, it is hardly open to doubt that we have got parent and child. Please excuse a short letter, for I am working as hard as I can manage.
Yours very truly, ELEANOR A. ORMEROD.
[The parasitic and other enemies of the “hill-grub” are so effective in their attacks that in the year following a great increase in numbers a normal level of occurrence is invariably restored.]
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