HYBERNATION OF INSECTS. 527 
Peubet , Others were exposed eyen to 56° below zero, without being 
injured. 
oh less degree of cold suffices to freeze many pup and larvee, in both 
which states the consistency of the animal is almost as fluid as in that of 
the egg. Their vitality enables them to resist it to a certain extent, and 
it must be considerably below the freezing point to affect them. The 
winter of 1813-14 was one of the severest we had had for many years, 
Fahrenheit’s thermometer having been more than once as low as 8° 
when the ground was wholly free from snow ; yet almost the first objects 
which I observed in my garden, in the commencement of spring, were 
numbers of the caterpillars of the gooseberry-moth (Abraxas grossulariata), 
which, though they had passed the winter with no other shelter than the 
slightly projecting rim of some large garden-pots, were alive and quite un- 
injured ; and these and many other larva never in my recollection were so 
numerous and destructive as in that spring: whence, as well as from the 
corresponding fact recorded, with surprise, by Boerhaave, that insects 
abounded as much after the intense winter of 1709, during which Fahren- 
heit’s thermometer fell to 0°, as after the mildest season, we may see the 
fallacy of the popular notion, that hard winters are destructive to insects.2 
But though many larvee and pup@ are able to resist a great degree of 
cold, when it increases to a certain extent they yield to its intensity and 
become solid masses of ice. In this state we should think it impossible 
that they should ever revive. That an animal whose juices, muscles, and 
whole body have been subjected to a process which splits bombshells, and 
converted into an icy mass that may be snapped asunder like a piece of 
glass, should ever recover its vital powers, seems at first view little less 
than a miracle ; and if the .reviviscency of the wheel animal (Rotifer vul- 
garis) and of snails, &c., after years of desiccation, had not made us familiar 
with similar prodigies, might have been pronounced impossible; and it is 
probable that many insects when thus frozen never do revive. Of the 
fact, however, as to several species, there is no doubt. It was first no- 
ticed by Lister, who relates that he had found caterpillars so frozen, that 
when dropped into a glass they chinked like stones, which nevertheless 
revived.’ Reaumur, indeed, repeated this experiment without success ; and 
found that when the larvae of Cnethocampa Pityocampa were frozen into 
ice by a cold of 15° R. below zero (2° F. below zero), they could not be 
made to revive.t But other trials have fully confirmed Lister’s observa- 
tions. My friend Mr, Stickney, before mentioned as the author of a 
valuable Essay on the Grub (larva of Tipula oleracea) — to ascertain the 
effect of cold in destroying this insect, exposed some of them to a severe 
frost, which congealed them into perfect masses of ice. When broken, 
their whole interior was found to be frozen. Yet several of these 
resumed their active powers. Bonnet had precisely the same result with 
the pupa of Pontia Brassice, which, by exposing to a frost of 14° R. below 
zero (0° F.), became lumps of ice, and yet produced butterflies®; and in 
an experiment made during Sir John Ross’s voyage on the caterpillars 
of a moth (Zaria Rossii) two of them revived, and one assumed the 
1 Tracts, 22. 
2 Vid. Spence in Transactions of the Horticult. Soc. of London, ii. 148. Compare 
Reaum. ii. 141. 
5 Lister, Goedart, De Insectis, 76, 
4 Reaum, ii, 142, 5 Qfuvres, vi. 12, 
