5 
If we now consider the condition of our common 
farm insects during autumn and winter, the time when 
we are commencing the farming operations for the next 
season, we shall see some of the reasons why they are 
uninjured even by severe cold. 
The winter-state, which we call “hybernation,” is not 
simply a torpidity caused by cold, for we find that in 
cases where the regular time for hybernation was not 
arrived insects have carried on their occupations quite 
undisturbed by a drop in the temperature of some 
degrees lower than the warmth of some weeks later, 
when they were retiring in due course to their winter 
quarters. 
Kirby and Spence give an instance in which for a 
week preceding the 14th of October (on which day great 
numbers of insects were noticed seeking hybernating 
spots) the temperature was never lower than 48° at 
night, and on that day was 58° in the shade; whilst on 
the 81st of the preceding August the greatest heat of the 
day was not more than 52°, thus showing a difference of 
six degrees more warmth even in the shade at the time 
of hybernation than six weeks earlier, when the seasonal 
or periodic influence was not acting. 
Hybernation appears to he quite a distinct condition 
from mere effect of cold; rather a constitutional seasoned 
influence in which insects, whilst they have still all their 
instinctive faculties in good order, prepare a shelter for 
the time of coming cold and want of food. They do not 
just pass into a state of torpor indifferently wherever 
they may he, but select some special locality under 
leaves or stones, or some safe protection ; or form a cell, 
or in some way supply themselves with shelter, and 
there they—or such of them as hybernate—pass into a 
quiet, motionless state, the animal functions decreasing 
in power with the increase of the cold; but still, even if 
totally frozen so that they can be broken like sticks, 
many kinds of caterpillars are not injured, so long as 
the freezing takes place in the shelters they have made 
for themselves. 
