586 



MAN AS A CONQUEROR 



cotton crops with other types of agricultural products. The cotton 

 boll- weevil lays its eggs in the young flower bud, while the larvae feed 

 on the substance within the bud, causing it to drop off, with the 

 consequent non-production of cotton fiber. Beetles also lay their 

 eggs in the young bolls of cotton, with the result that they become 

 discolored, thus ruining the cotton produced. It is estimated that 



SPREAD OF THE COTTON BOLL WEEVI L, 1892-1932 



U.5.0CPARTMErtT or ACRICUCT 



tAU or AGRICULTUdAi CCONOMlCS 



over half of the cotton crop is destroyed by the boll-weevil. Because 

 of protection offered by the cotton boll, the weevil is difficult to ex- 

 terminate. Parasitic insects have been introduced to prey upon this 

 pest ; infected bolls and stalks are burned ; crops are rotated and the 

 ground plowed under for two or three years at a time in order to 

 destroy the wintering weevil pupae. However, nothing has succeeded 

 in stopping the boll-weevil's advance over the cotton-raising South. 

 Today it is considered to be one of the greatest crop-destroying 

 imported pests. The gypsy moth, the cabbage butterfly, the codling 

 moth, and scores of others give rise to untold billions of caterpillars 

 each year which strip our trees and shrubs of their leaves. Locusts 

 move in swarms across the country, leaving a wake of devastation in 

 their path. Plant lice and scale insects take their toll of fruit and 

 forest trees, and beetles, too, such as the hickory borer, threaten the 

 existence of all of the hickories in the eastern part of this country. 

 The Englemann spruce beetle and the mountain pine bark beetle, 

 which have already done enormous damage to the forests of the Far 

 West, are rapidly spreading their areas of destruction. Insects from 

 almost every order do harm to man, so why multiply the list. 



