HYBERNATION OF INSECTS. 437 



a cavity exactly the size of their bodies, to which they 

 give all round a coating- of silk"; and the larvaB of Pa- 

 pilio 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 ludi- 

 crous. 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 ca- 

 terpillars go out of its case, the hind feet first, to eject 

 a similar grain ; so that it would seem the society have 

 on their establishment a scavenger, whose business it 

 is to sweep the streets and convey the rejectamenta to 

 one grand repository^! This, however singular, is 

 rendered not improbable, from the fact that beavers 

 dig- in their habitations holes solely destined for a like 

 purpose '^ 



A very considerable number of insects hybernate in 

 the perfect state, chiefly of the orders Coleoptera, Hemi- 

 ptera, Jlj/mcnoptera, and Diptera, and especially of the 

 first. Papilio Urticce, lo, and a few other lepidopterous 

 species, with a small proportion of the other orders, 



^ Bi-alim, Ins. Kal. ii. 39. 118. 



^ I have reason to tliink. (iiat the larvaB of some species of Hemerohius 

 thus protect themselves by a net-like case of silken threads; at least I 

 found one fo-dny (December 3d, 1816) inclosed in a case of this de- 

 scription 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, 

 Avhich state, according to Reaumur, is assumed soon after the cocoon is 

 fabricated (iii. 3S5); and because the same author describes the cocoons 

 of thesL- insects as perfectly spherical and of a very close texture (381); 

 w hile this was oblong, and the net-work with rather wide meshes. 



' (Euv.xi. 72. " Ibid. ix. 167. 



