1 06 Queries and Answers, 



body is thus pierced with so many wounds, seems to bear it very patiently, 

 and does not turn upon the fly, as he would be certain to do upon another 

 caterpillar should it venture to pinch him, a circumstance by no means 

 unusual. Sometimes, indeed, he gives a slight jerk ; but the fly does not 

 appear to be at all incommoded by the intimation that her presence is 

 disagreeable," 



" The eggs, it may be remarked, are thrust sufficiently deep to prevent 

 their being thrown off when the caterpillar casts its skin ; and, being in due 

 time hatched, the grubs feed in concert on the living body of the caterpil- 

 lar. The most wonderful circumstance, indeed, of the whole phenomenon, 

 is the instinct with which the grubs are evidently guided to avoid devouring 

 any vital part, so that they may not kill the caterpillar, as in that case it 

 would be useless to them for food. When full grown, they even eat their 

 way through the skin of the caterpillar without killing it; though it gene- 

 rally dies in a few days, without moving far from the place where the grubs 

 have spun their group of silken cocoons in which to pass the winter." 



The above insect has long ago been described and figured by Albin, in 

 his History of English Insects, plate 1.; which figure also has been in part 

 exactly copied by Wilkes, in his English Moths mid Butterflies (see his plate 

 of the large garden white butterfly). As the Microgaster is the destroyer 

 of that " pest of gardens," Pontia brassicae, it may be considered a bene- 

 ficial insect. 



Very many other lepidopterous larvae are subject to be preyed upon by 

 parasites analogous to Microgaster glomeratus, and thus occasionally cause 

 no small disappointment to the breeders of insects, who, instead of seeing a 

 brilliant butterfly or moth proceed from a chrysalis, as they naturally ex- 

 pected, are presented in its room with a number of small flies. I once 

 fed in confinement a caterpillar of Lasiocampa quercus Stephens (large 

 eggar moth), which, after having spun its cocoon, and changed to a pupa, 

 in due time produced a host of small ichneumons*, with long ovipo- 

 sitors, somewhat resembling /chneumon manifestator in miniature. The 

 generation of these parasites was a subject which seems to have greatly 

 perplexed our earlier entomologists : " mira, imo vix credibilia aut ante au- 

 dita," " wonderful things, nay, scarcely credible or before heard of," are the 

 words of Joannes Goedartius, in reference to the above Microgaster ; and 

 after mentioning the case of a second and still different parasite which he 

 reared from the same species of the cabbage butterfly, he thus expresses his 

 astonishment : — " Haec ipse expertus sum, et non sine admiratione obser- 

 vavi; quia praeter, imo contra, consuetum naturae ordinem esse videtur, ex 

 uno eodemque animali, diversae speciei prolem generari j atque unum idem- 

 que brutum, tribus diversis modis procreare; quae tamen in his erucis, ex iis 

 quae breviter enarravi, manifesta sunt." " These things I have myself 

 found by experience, and observed not without astonishment ; because it 

 seems beside, nay, contrary to, the usual course of nature, that from one and 



* The cocoon and specimens of the ichneumons I herewith send you. 

 The latter, now in my possession, amount to 48 in number ; some have 

 probably been lost, and others, I know, have been given away to different 

 collectors. The variance in the size and appearance of the specimens sent, 

 I conclude, arises from sexual difference; the larger ones (females?) are 

 far the most numerous. On referring to these specimens (which I could 

 not exactly lay my hand on M'hen T first sent you the notice) I find they 

 resemble /chneiimon manifestator much less than I had supposed. This 

 thought has occurred to me : does each species of ichneumon invariably 

 keep to one and the same species of moth or butterfly ? or do many of 

 them attack larvae promiscuously? They are interesting creatures and 

 far more useful than we are commonly aware. 



