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LETTER XXYVI. 
ON THE HYBERNATION OF INSECTS. 
Ir insects can boast of enjoying a greater varicty of food than many other 
tribes of animals, this advantage seems at first sight more than counter- 
balanced in our climates by the temporary nature of their supply. The 
graminivorous quadrupeds, with few exceptions, however scanty their bill 
of fare, and their carnivorous brethren, as well as the whole race of birds 
and fishes, can at all seasons satisfy, in greater or less abundance, their 
demand for food. But to the great majority of insects, the earth for nearly 
one half of the year is a barren desert, affording no appropriate nutriment. 
As soon as winter has stripped the vegetable world of its foliage, the vast 
hosts of insects that feed on the leaves of plants must necessarily fast 
until the return of spring: and even the carnivorous tribes, such as the 
predaceous beetles, parasitic Hymenoptera, Sphecina, &c. would at that 
period of the year in vain look for their accustomed prey. 
How is this difficulty provided for? In what mode has the Universal 
Parent secured an uninterrupted succession of generations in a class of 
animals for the most part doomed to a six months’ deprivation of the food 
which they ordinarily devour with such voracity? By a beautiful series of 
provisions founded on the faculty, common also to some of the larger 
animals, of passing the winter in a state of torpor—by ordaining that the 
insect shall live through that period, either in an incomplete state of its 
existence when its organs of nutrition are undeveloped, or, if the active 
epoch of its life has commenced, that it shall seek out appropriate hy- 
bernacula, or winter quarters, and in them fall into a profound sleep, during 
which a supply of food is equally unnecessary. 
In two of the four states of existence common to insects, in which 
different tribes pass the winter, namely, the egg and the pupa state, the 
organs for taking food (except in some cases in the latter) are not de- 
veloped, and consequently the animal is incapable of eating. The existence 
-of insects in these states during the winter differs from their existence in 
the same form in summer only in the greater length of its term. In both 
seasons food is alike unnecessary, so that their hybernation in these cir- 
‘cumstances has little or nothing analogous to that of larger animals. With 
this, however, strictly accords their hybernation in the larva and imago 
states, in which their abstinence from food is solely owing to the torpor 
that pervades them, and the consequent non-expenditure of the vital 
powers.—I shall attend to the peculiarities of their hybernation in each of 
these states in the order just laid down ; premising that we have yet much 
to learn on this subject, no observations having been instituted respecting 
the state in which multitudes of insects pass the winter. 
