HIBERNATION. 



103 



ACTIVITY DURING THE HIBERNATION PERIOD. 



It is natural to expect that during warm periods of winter the tem- 

 perature will rise to a point which forces the weevils into activity., 

 Of course, the weevils under the lightest shelter are the ones which 

 first become active. It is these warm periods which cause the inter- 

 mittent development of the immature stages in dry bolls left in the 

 fields. In some winters the hibernation is incomplete throughout 

 the cotton belt, and in the extreme South it is probably so almost 

 every winter. This same temperature condition is responsible for 

 the growth of sprout cotton, which affords food in the warm periods. 

 Observations were made in January, 1907, on weevils feeding on 

 sprout cotton at Victoria, Tex., at a mean temperature of 67° F. 



DURATION OF HIBERNATION PERIOD. 



AVERAGE LENGTH OF HIBERNATION PERIOD. 



Many factors must be considered in arriving at the average length 

 of the hibernation period. The time of entrance, condition of the 

 weevils on entering, temperature and humidity before and during 

 hibernation, and nature of shelter, all have a decided effect upon the 

 duration of hibernation. In a series of condensed summaries we 

 have attempted to show how some of these factors act. 



In Table XXXVIII is to be found a general summary of the nine 

 large experiments conducted, with the extreme variations in each 

 series. From this table it appears that in the years 1906 to 1911 the 

 hibernation period has ranged between 62 and 255 days, and that in 

 1909 the range fell short only 1 day of this maximum range. It 

 also appears that the average duration in Texas is 26 days shorter 

 than in Louisiana. The period of emergence extends from Feb- 

 ruary 15 to July 1. 



Table XXXVIII. — Extremes of variation in duration of hibernation by the boll weevil. 



