INSECTS INJURIOUS TO COTTON 



239 



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 

 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 pupse in winter 

 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 FlG - 201. Egg of bollworm; 



. . . side and top views. Highly 



to be avoided, and as an early crop magnified (From Quaintance 



is less injured by almost all cotton and Brues > u - s - De Pt- Apr.) 



insects, the planter should adjust his methods to secure earliness. 



As the eggs are laid mostly on the cotton leaves and the littlo 





FIG. 202. Bollworms showing variation in color, upper larva green, middle 

 rose, and lower, dark brown twice natural size. (After Quaintance and 

 Brues, U. S. Dept. Agr.) 



caterpillars nibble the surface before boring into the bolls, the 

 poisoning of the foliage when the eggs are hatching will result in 

 a very material reduction of the subsequent injury. Paris green 



