SEASONAL STUDIES OF INSECT CONTKOL. 



19 



Table V was based, as may be seen, upon the examination of 9,256 

 weevil stages, of which 1,926 were killed by climate, 1,067 by pred- 

 ators, and 576 by parasites. In other words, the insect enemies 

 killed 17.74 per cent, of wliich 11.52 per cent were killed by predators 

 and 6.22 per cent by parasites. July and August are the principal 

 months for attack upon hanging bolls. 



Summarizing the four preceding tables, Table VI is presented to 

 show the monthly rate of mortality in all classes of infested forms. 



1 /JPRfL 



M/IY 



jaA/£ 



JULY 



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MPy^/V^Sy? 



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60 

 50 



f 



.30 

 \ 

 20 



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 / 

















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 1 

 I 

 1 













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Fig. 1.— Diagram illustrating the monthly percentage of mortality of immature boll weevils due to 



insect enemies. (Original.) 



It will be noticed that in each year certain months have been omitted 

 and it must be explained that the reason therefor has been the 

 necessity of making these examinations only when other work was 

 not pressing. An analysis of this table is more readily made by 

 reference to the accompanying diagram (fig. 1), which demonstrates 

 conclusively that August is the month during wliich the insect enemies 

 of the boll weevil are most active. 



