The method adopted was to enclose the insects in a glass tube, and
place them out of doors all night; and though the tube was frequently
covered with frost, they soon revived in the warm temperature of a
room. It is perhaps scarcely possible to estimate the degree of cold
which insect life will bear without destruction, since many of these
creatures survive the terrible winters of the arctic regions. Still, a
knowledge of the effects of reduction of temperature will be valuable,
as affording data by which to judge of the effects and probable
duration of visitations of insects, and of the nature of the
precautionary measures to be adopted. In an experiment of alternate
temperature from 40° to 65° tried for five days on a bee, the creature
at last 'ceased to give any sign of vitality.'

The influence of heat appears to be much more rapid than that of cold:
a fly exposed to a temperature of 120°, died in two or three minutes;
and 113° proved fatal to another; while a third, placed in a
temperature increased gradually to 96°, remained alive for more than
an hour. Others bore from 80° to 90° for two hours; and in one
instance, a fly survived from 86° to 100° for several hours, but
became uneasy with a slight rise, and died at 105°. A bee, taken on
March 15, from a temperature of 45°, was exposed to 80° without any
apparent diminution of activity; at 90° it ceased to buzz; and at 96°,
ceased altogether to move, and did not revive. Although these results
are too few to enable us to determine the laws with respect to the
influence of temperature on insects, they may serve a purpose, in
shewing that the effect is not that gradual one of hybernation, where
activity and torpor succeed each other but slowly.

In the series of experiments with gas, it was found that flies placed
in carbonic acid gas became instantly motionless, and died if left for