THYBERNATION OF INSECTS. 521 
other than a slight covering ; while the more tender species either enter 
the earth beyond the reach of frost, or prepare for themselves artificial 
cavities ip substances, such as moss and rotten wood, which conduct heat 
with difficulty, and defend them from an injuriously low temperature. It 
does not appear that any perfect insect has the faculty of fabricating for 
itself a winter abode similar to those formed of silk, &c., by some larva. 
Schmid, indeed, has mentioned finding Rhagium mordax and Inquisitor in 
such abodes, constructed, as he thought, of the inner bark of trees ; but 
these, as Illiger has suggested, were more probably the deserted dwellings 
of lepidopterous larvae, of which the beetles in question had taken posses- 
sion! Most insects place themselves in their hybernacula in the attitude 
which they ordinarily assume when at rest ; but others choose a position 
peculiar to their winter abode. So most of the ground beetles (Zu- 
trechina) adhere by their claws to the under side of the stone which serves 
for their retreat, their backs being next to the ground ; in which posture, 
probably, they are most effectually protected from wet. Gyrohypnus san- 
guinolentus, and other rove-beetles of the same genus, coils itself up like a 
snake, with the head in the centre. 
The majority of insects pass the winter in perfect solitude, Occasion- 
ally, however, several individuals of one species, not merely of such insects 
as Anchomenus prasinus, a beetle, Pyrrhocoris apterus, a bug, &c., which 
usually in summer also live in a sort of society, but of others which are 
never seen thus to associate, as Haltica oleracea, Carabus intricatus, and 
several Coccinelle, &c.,are found crowded together, This is perhaps often 
more through accident than design, as individuals of the same species are 
frequently met with singly; yet that it is not wholly accidental seems 
proved by the fact that such assemblages are generally of the same genus 
and even species. Sometimes, however, insects of dissimilar genera and 
even orders are met with together. Schmid once in February found the 
rare Lomechusa strumosa torpid in an ant-hill, in the midst of a conglome- 
rated lump of ants, with which it was closely intertwined.? 
By far the greater proportion of insects pass the winter only in one or 
other of the several states of egg, pupa, larva, or imago, but are never 
found to hybernate in more than one. Some species, however, depart 
from this rule. Thus Aphis Rose, Cardui, and probably many others of 
the genus, hybernate both in the egg and perfect state* ; Cynthia Cardui, 
Gonepteryx Rhamni, and some other species, usually in the pupa, but often 
in the perfect state also ; and Vanessa Lo, according to the accurate Brahm, 
in the three states of eg, pupa, and imago.* It is probable that in these 
instances the perfect insects are females, which, not having been impreg- 
nated, have their term of life prolonged beyond the ordinary period. 
The first cold weather, after insects have entered their winter quarters, 
produces effects upon them similar to those which occur in the dormouse, 
hedgehog, and others of the larger animals subject to torpor. At first a 
partial benumbment takes place ; but the insect, if touched, is still capable 
of moving its organs. But as the cold increases all the animal functions 
cease. The insect breathes no longer, and has no need of a supply of air® ; 
its nutritive secretions cease ; no more food is required ; and it has all the 
1 Tilig. Mag. i. 216. 2 Thid. i, 491. 
3 Kyber in Germar, Magazin der Entomologie, ii. 2. 
4 Ins. Kal. ii. 188. § Spallanzani, Rapports de U Air, &e.; i. 50s 
