HIBERNATION. 



105 



Knowing that the time of entrance affects the percentage of sur- 

 vival, it is also reasonable to expect an effect upon the duration of the 

 hibernation period. Table XXXIX has been constructed to show 

 the average duration and average date of emergence at each locality 

 for all weevils entering hibernation in each half month during the 

 several seasons of the experiments. It will be noted that the length 

 of the period, with a few minor exceptions, decreases in accordance 

 with the lateness of entrance. It is very strikingly shown that in any 

 given period of entrance the duration in Texas is considerably shorter 

 than in Louisiana. On the other hand, it is impossible to show from 

 this table any progression in the average date of emergence. 



The diagram (fig. 22) shows graphically the correspondence between 

 date of installation and period of hibernation and emphasizes the 

 differences between Texas and Louisiana. 



RELATION OF SHELTER TO DURATION OF HIBERNATION. 



That the nature of the hibernating quarters has a direct bearing 

 upon the duration of the period is to be gathered from the records of 

 Messrs. Newell and Dougherty made at Mansura, La., in 1909, which 

 are abstracted below: 



Table XL. — Comparison of length of hibernation of the boll weevil in different shelters 

 at Mansura, La., 1909. 1 



i This table and the following statements are extracted from Cir. 31, State Crop Pest Commission of 

 Louisiana. 



Consideration of Table XL reveals the interesting fact that weevils 

 hibernating in the cool, shaded situations in timber remained in hi- 

 bernation an average of about seven days longer than those 

 hibernating in the open field. Weevils which hibernated in moss in 

 the swamp remained in hibernation practically 200 days, and those 

 winch passed the winter in moss on trees in the open field remained in 

 hibernation 191 days. In marked contrast to this the weevils that 

 hibernated in a general assortment of materials in the open field 

 remained in hibernation only 169 days, though gathered from the 

 cotton fields at exactly the same date in the fall of 1908. This proves 

 the dangerous nature of the moss, for it really causes the weevils in it 

 to remain in hibernation for nearly a month longer than they would 

 if hibernating in other materials. 



Table XL also illustrates the influence of temperature upon the dura- 

 tion of the hibernation period, for there is no doubt that it is the temper- 



