HYBERNATION OF INSECTS. 



353 



of insects, forms a covering of pieces of wood lined with fine 

 silk ; those of Hepiolus Humuli, Xylina radicea, and some 

 other moths, excavate under a stone a cavity exactly the size 

 of their bodies, to which they give all round a coating of 

 silk 1 , and the larvae of Pieris Cratcegi inclose themselves in 

 autumn in cases of the same material and thus pass the 

 cold season, in small societies of from two to twelve, under a 

 common covering formed of leaves. Bonnet mentions a trait 

 of the cleanliness of these insects which is almost ludicrous. 

 He observed in one of these nests a sort of sack containing 

 nothing but grains of excrement ; and a friend assured him 

 that he had seen one of these caterpillars partly protrude 

 itself out of its case, the hind feet first, to eject a similar 

 grain; so that it would seem the society have on their es- 

 tablishment a scavenger, whose business it is to sweep the 

 streets and convey the rejectamenta to one grand reposi- 

 tory ! 3 This, however singular, is rendered not improbable 

 from the fact that beavers dig in their habitations holes solely 

 destined for a like purpose 4 , as also do badgers. 



A very considerable number of insects hybernate in the 

 perfect state, chiefly of the orders Coleoptera, Hemiptera, 

 Hymenoptera, and Diptera, and especially of the first. Va- 

 nessa UrticcB, Io, and a few other lepidopterous species, with 

 a small proportion of the other orders, occasionally survive 

 the winter; but the bulk of these are rarely found to hy- 

 bernate as perfect insects. Of coleopterous insects, Schmid, 

 to whom we are indebted for some valuable remarks on the 

 present subject 5 , says that he never found or heard of any 

 entomologist finding a hybernating individual of the common 

 cock-chafer {Melolontha vulgaris), or of the stag-beetle (Lu- 



1 Brahm, Ins. Kal. ii. 59. 118. 



2 I have reason to think that the larva? of some species of Hemerobius thus 

 protect themselves hy a net-like case of silken threads ; at least I found one to- 

 day (December 3d, 1816) inclosed in a case of this description concealed under 

 the bark of a tree ; and it is not very likely that it could be a cocoon, both 

 because the inhabitant was not a pupa, which state, according to Reaumur, is 

 assumed soon after the cocoon is fabricated (iii. 385.), and because the same 

 author describes the cocoons of these insects as perfectly spherical and of a very 

 close texture (384.), while this was oblong, and the net- work with rather wide 

 meshes. 



3 (Euv. ii. 72. 4 Ibid. ix. 167. 

 9 Illig. Mag. i. 209—228. 



VOL. II. A A 



