16 



INSECT ENEMIES OF THE BOLL WEEVIL, 



A study of Table II, on the mortality due to insects in fallen 

 squares, shows that the principal insect work is that of predatory 

 insects and, furthermore, that the total insect control is, as a rule, 

 less than the climatic control. The table embraces the examination 

 of 63,985 weevil stages of which 17,596 were killed by climate, 13,958 

 by predators, and 2,849 by parasites. In other words, the average 

 percentage of control in fallen squares by all kinds of insects is 26.2 

 per cent, or 21.8 per cent by predators and 4.4 per cent by parasites. 



A further study of Table II shows that the predators have in each 

 year done their most valuable work in the month of August. The 

 parasites, however, have shown considerable variation in the month 

 of their best work. In 1906 the highest average percentage was in 

 October; in 1907 it was in June; in 1908 in November; and in 1909 

 in July. 



Table III. — Monthly mortality of the boll weevil due to insects in hanging squares. 



Table III shows that the principal insect work in hanging squares 

 is that of parasitic insects and, furthermore, that the total insect 

 control in hanging squares is each year higher than the climatic 

 control. Tliis table embraces the examination of 14,611 weevil 



