INSECTS INJURIOUS TO COTTON 255 



becomes so abundant late in the season as to effectively check 

 the increase of the pest. 



Wasps are effective enemies of the bollworms, provisioning 

 their nests with them. Several species of tachina-flies parasitize 

 the caterpillars, while not a few are killed by a bacterial disease. 

 One of the most important natural factors in reducing their num- 

 bers, however, is their own tendency to cannibalism, the larger 



FIG. 183. Bollworm boring into green tomato. (After Quaintance and 

 Brues, U. S. Dept. Agr.) 



caterpillars attacking and destroying the weaker with a consequent 

 marked reduction in numbers. 



Control. As in protecting corn from this pest, the most effect- 

 ive means is the plowing of the land containing the pupae in win- 

 ter or late fall. 



Early planting of early fruiting varieties of cotton, with a 

 liberal use of fertilizers, and frequent cultivation, so as to hasten 

 the maturity of the crop, will result in a good crop being made 

 before the worst injury by the bollworm occurs. These cultural 

 measures ensure the best crops even where there are no insects 

 . to be avoided, and as an early crop is less injured by almost all 

 cotton insects, the planter should Adjust his methods to secure 

 earliness. 



