INSECT PESTS OF COTTON 481 



be common throughout the cotton belt in fifteen or twenty 

 years. The boll weevil is a grayish or reddish-brown insect 

 about one-fourth of an inch long which lays its eggs in the 

 squares soon after the blossoms fall. The egg hatches and 

 the rapidly-growing larva eats the contents of the young boll. 

 In about ten days, it turns into a pupa and a few days later 

 emerges as a weevil. This insect is very destructive to the 

 cotton crop when it first appears in a district, but its ravages 

 decrease as farmers learn better how to control it. The most 

 effective methods are the rotation of crops, frequent culti- 

 vation to knock off and bury the infested squares, and the 

 early planting of early varieties, as the insects do not become 

 numerous till late in the season. 



The bollworm is the larval stage of a moth which lays its 

 eggs on the stems and leaves of cotton and other plants. 

 The worm eats the leaves of the cotton and also buries itself 

 in the half-grown boll, eating the young seeds. The methods 

 recommended for the destruction of the boll weevil are also 

 effective with the bollworm. In addition, poisoning with 

 Paris green and the use of trap crops are recommended. As 

 the moths lay their eggs on the most readily available food 

 plants, many of the worms may be destroyed early in the 

 season by planting occasional rows of corn through the cotton 

 field and cutting and destroying these when the worms 

 become numerous. 



631. Diseases. Of the numerous diseases of cotton which 

 occur in various sections of the South, perhaps the most 

 important are cotton wilt and root rot. Cotton wilt is 

 somewhat similar to flax wilt. The fungus enters the young 

 plant through the root hairs, and its mycelium fills the cells 

 of the plant, preventing it from obtaining water. The plants 

 become dwarfed, turn yellow, and usually die. As in flax, 

 certain plants seem to be resistant to the disease; if seed is 

 is 



