86 



BIBERNATION OF THE COTTON BOLL WEEVIL. 



The most apparent Tact is that there is a consistent inerease in 

 duration of life without food in both sexes in a northern locality, as 

 at Dallas, as compared with a southern locality, as at Victoria, while 

 Calvert occupies an intermediate position both in the starvation 

 period and geographically. Lower temperatures are obviously directly 

 correlated to the degree of activity of the insects and thus determine 

 directly t he limit of endurance withoul food. But in no case is there 

 any very marked variation between the sexes in the same locality. 



It appears that practically two-thirds of all weevils died during 

 t he first ten days after their emergence. One-fourth of the total num- 

 ber tested lived to between eleven and twenty days. Beyond twenty 

 days the percentage surviving becomes comparatively small, and 

 between fifty and ninety days the percentage for each ten-day 

 period is rather surprisingly uniform. It is very evident, however, 

 that even in a season when the bulk of emergence may occur as 

 unusually early as it did in 1907 it would be absolutely impossible 

 to exterminate the weevil by any possible delay in the time of plant- 



ing cotton. 



LONGEVITY OF FED WEEVILS AFTER EMERGENCE FROM HIBER- 

 NATION. 



The records indicating the longevity of weevils which were fed 

 after their emergence from hibernation have been prepared in a 

 similar way to show results comparable with those for unfed weevils 

 which have just been given. They form the second part of the com- 

 parative series of experiments to determine longevit}'. The condi- 

 tions of food supply, while kept as favorable as was possible, could 

 not at best equal the natural conditions in the field, although the 

 weevils were evidently saved the trouble which they might have 

 experienced in the field of finding their first food supply. The con- 

 siderations which have previously been mentioned in regard to the 

 effect of high temperature and excessive moisture in the jars when 

 exposed to sunshine apply with fully as much force to the fed as to 

 the unfed series of experiments. 



Table XLIV. — Longevity of weevils fed after emergence from hibernation, March- to 



September, 1907. 



Locality. 



Number 



of scries 



tested, 



led. 



Total 

 weevils 

 emerged. 



Number of weevils in 

 series. 



Maximum life. 



Average duration of life. 



Total. 



<? 



9 



S 



9 



S 



9 



Both 



Texas: 



Dallas 



Culver! 



Victoria 



2fi 



L>0 



Till 

 I. 150 



mil 



71.-. 



1,349 



t'.U) 



mi 



564 



inn 

 92 

 84 



ins 

 lis 



9 



l.-,. l 



30.7 

 14.2 



30.0 



11.7 



Total and 

 average . 



53 





2,965 



1 . :V27 



130 



lis 



25, 2 







