February, ’24] 
BABCOCK: CORN BORER BIOLOGY 
123 
In connection with the graphical study of the environment, experi¬ 
ments were carried on to check the hypotheses formulated. It soon 
became evident that the hibernation period of the insect was a very 
critical period as regards the presence of available moisture in the 
hibernating quarters. In fact, the hibernating larva is quite sensitive 
to the fluctuations of moisture of very short duration. The results of 
the experiments upon the hibernation period are of enough importance 
to warrant a brief summary. 
I— Regular weekly collections of larvae, previously experiencing nor¬ 
mal hibernating conditions were subjected to uniform incubator con¬ 
ditions of 80 deg. Fahr. and humidity saturation. There was exhibited 
during the first portion of the hibernation period, approximately the 
first six weeks, a distinct requirement of exposure to temperatures below 
the threshold of development, to assist the breaking up of hibernation. 
This requirement sharply decreases after this particular period, while the 
warmth and moisture requirements increase. It was found that the 
hibernating larvae are very sensistive to available moisture throughout 
the period, and it is essential that the moisture requirement be supplied 
by actual contact. High air humidity will not suffice. 
As the normal time approaches for the emergence from hibernation, 
the larvae prefer drier hibernating quarters, but at the same time 
require contact with moisture obtained from the periodic drenching of 
the host plant by rainfall. 
II— An experiment to determine what period or periods during 
hibernation the insect is most susceptible to moisture fluctuations. 
Larvae were deprived of from one to six consecutive months of normal 
field moisture conditions and collections made at the time of normal 
emergence to determine the effect of the treatment. 
The results show that if any month from November to April inclusive 
is dry, there results increased mortality and longer time is required to 
emerge from hibernation than is normal. Arranged according to the 
highest mortality if dry, March produces the greatest delay, then April, 
February, January and November. As the period of dryness during 
hibernation is lengthened, the mortality during the spring corresponding¬ 
ly increases. 
III— An experiment to determine what effect abnormal conditions of 
moisture during hibernation would have upon the seasonal history during 
the ensuing growing season. 
(a) A large quantity of material kept in insectary during winter 
