1914} Longevity of Insects 339 
were mixed to avoid the possibility of having a set of larve 
from the same part of the mass of cocoons. The test tubes 
were placed in round paste board boxes which gave room for 
seven of them and insured perfect darkness—a long strip of 
paper was placed in the box upon which was kept a complete 
record of the temperature treatment. 
The insects were kept at three temperatures—room temper- 
ature as a check, low temperature in a refrigerator, usually 
about 43° F., or high temperature 86 to 96° F., maintained by 
an electric light. 
The first experiment performed was to place a set of test 
tubes at the high temperature—the larve of this experiment all 
died in twenty-six days except one, which pupated, but did not 
hatch. An attempt was then made to bring the larve out of 
their hibernating condition by first chilling and then heating. 
Sets were placed in the refrigerator for varying lengths of time 
—it was found that an exposure to cold of from seven to four- 
teen ‘days greatly lengthened the life of the larve and raised 
the percentage of pupation and of hatch. This percentage is 
much higher than that obtained by heat without previous 
chilling or by exposure to room temperature as in the check. 
After fourteen days it will be seen by reference to Chart I 
that the longevity does not increase and that no pupation occurs. 
Four conclusions can be drawn from Chart I— 
1. That pupation of hibernating Codling moth larve is not 
usually brought about by heat. 
2. That exposure of these larve to a low temperature for 
from one to two weeks followed by heat results in pupation, 
hatch and increase in longevity of those larvae which do not 
pupate. 
3. That after twenty-one days exposure to low temperature, 
heat does not result in pupation nor is the longevity increased. 
4. ‘The number of days which the larve that die, live at the 
high temperature, is approximately equal to the total number of 
days, the other larve take to pupate. 
In order to arrive at some conclusion about these experi- 
ments, first, let us consider the nature of hibernation. Hiber- 
nation takes place in many forms of insects, fish, Amphibia, 
Mollusks, birds, Mammals and even in man. Peasants of 
Russia, according to Cleghorn (12-13) with the approach of 
