SEASONAL STUDIES OF INSECT CONTROL. 



17 



stages of wliich 2,604 were Idllcd by climate, 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. 



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 



