432 HYBERNATION OF INSECTS. 



and the larvae of Pio'is 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 cater- 

 pillars 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 establishment a scavenger, whose 

 business it is to sweep the streets and convey the rejec- 

 tamenta 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 

 pet feet state, chiefly of the orders Coleoptera, Hemiptei-aj 

 Hijmenoptera^ and Diptera, and especially of the first. 

 Vanessa Urticce^ lo, and a few other lepidopterous spe- 

 cies, with a small proportion of the other orders, occa- 

 sionally survive the winter; but the bulk of these are 

 rarely found to hybernate as perfect insects. Of cole- 



* I have reason to think that the larvae of some species of Heme- 

 rob'ius thus protect tiieniselves by a net-like case of silken threads ; 

 at least I found one to-day (December 3d, 181G) 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. 38o) ; and because the same author 

 describes the cocoons of these insects as perfectly spherical andofa 

 very close texture (384) ; while this was oblong, and the net-work 

 with rather wide meshes. 



" lEuv. ii. 72. ' Ibid. ix. 107. 



