SEASONAL STUDIES OF INSECT CONTKOL. 



17 



r 



stages of which 2,604 were Idlled by cHmate, 1,746 by predators, 

 and 2,897 by parasites. In other words the average percentage 

 of control by all kinds of insects is 31.61 per cent, or 11.93 per cent 

 by predators and 19.68 per cent by parasites. It appears that July 

 and August are usually the best months for parasite control in hang- 

 ing squares. 



Table IV. — Monthly mortality of the loll weevil due to insects 



in hanging bolls. 





Bolls 

 exam- 

 ined. 



Stages 

 found. 



Stages killed by- 



Percentage of stages killed. 



Months. * 



Cli- 

 mate. 



Preda- 

 tors. 



Para- 

 sites. 



Total. 



Preda- 

 tors. 



Para- 

 sites. 



All in- 

 sects. 



1906 



145 



2,947 



23,454 



6,210 



399 







290 



2,977 



1,555 



147 







28 

 416 

 198 



21 





 14 



742 

 188 

 11 





 

 19 

 23 

 3 



0.0 

 14.5 

 39.5 

 26.3 

 23.8 



0.0 



4.8 

 24.9 

 12.1 



7.5 



0.0 







.6 



1.5 



2.0 



0.0 



July 



4.8 



Ausust 



25 5 





13.6 



October 



9.5 







Totals and averages for 

 1906 



33, 155 



4,969 



663 



955 



45 



35.9 



21.9 



0.9 



22.8 







1907 



50 



50 



1,272 



5 



7 

 330 



1 



1 



115 











51 



1 

 



4 



40.0 



14.3 

 51.5 





 15.4 



20.0 







1.2 



20.0 



July 









16.6 







Totals and averages for 

 1907 



1,372 



342 



117 



51 



5 



50.6 



14.9 



1.4 



16 3 







1908 

 June 



2,227 



4,450 



1,123 



933 



238 

 405 

 200 

 98 



34 

 125 

 22 



8 



6 

 26 

 20 



4 



21 

 13 

 

 1 



29.7 

 40.5 

 21.0 

 13.2 



2.5 



6.4 

 10.0 

 4.1 



8.8 



3.2 







1.0 



11.3 



July 



9.6 



August 



10.0 



September 



5.1 







Totals and averages for 

 1908 



8,733 



941 



189 



56 



35 



29.7 



5.9 



3.7 



9.6 







1909 

 January 



1,616 

 716 

 608 



402 

 115 

 56 



133 

 12 

 14 



25 

 49 

 12 



11 

 2 

 1 



42.0 

 54.7 

 48.2 



6.2 

 42.6 

 21.4 



2.7 

 1.7 

 1.7 



8.9 



February . . 



44.3 



March 



23.1 







Totals and averages for 

 1909 



2,940 



573 



159 



86 



14 



45.2 



15.0 



2.4 



17.4 







In fallen bolls the principal insect work is that accomplished by 

 predatory insects, and the total insect control has been less than 

 the climatic control except in the year 1906. Table IV covers an 

 examination of 6,825 weevil stages, of which 1,128 were killed by 

 climate, 1,148 by predators, and only 99 by parasites. Tliis means 

 that 18.2 per cent of all the stages were killed by insects, or 16.8 

 per cent by predators and 1.4 per cent by parasites. In this class 

 of infested forms it is also noticeable that the principal work by 

 the predators is accomplished during the month of August. 

 16844°— Bull. 100—12 2 



