BIOLOGY AND HUMAN WELFARE 409 



The Potato Beetle first began to attract attention about 

 eighty years ago when it transferred its activities from certain weeds 

 in the Colorado region to the recently introduced Potato plant, 

 and since that time it has spread all over the United States and 

 has emigrated to Europe to become one of the serious insect pests. 

 Large masses of yellow eggs are deposited by the beetles on the 

 under surface of Potato leaves which serve as food for the cater- 

 pillars until they are full grown and ready to pupate in the ground. 

 Two broods of adults are usually produced annually to carry on 

 the depredation. 



Among the most destructive parasites of Wheat, Rye, and Bar- 

 ley, nearly the world over, is the Hessian Fly which was intro- 

 duced into America toward the end of the eighteenth century. 

 The life history is especially adapted to the growth of wheat, 

 and two or three broods of the insect develop in one year. For- 

 tunately, it has numerous parasites of its own that hold it some- 

 what in check. 



The European Corn Borer has long been distributed over 

 a large part of the Old World but only recently has reached Amer- 

 ica. Starting in New England, it is rapidly moving westward 

 and bids fair before long to infest the entire corn-raising area of 

 the continent. The destructive stage, of course, is the caterpillar 

 which, throughout most of the insect's range, spends the winter 

 in the stem of its food plant and gives rise to the adult moth 

 early the following summer. Unfortunately, however, in New Eng- 

 land there are two generations annually, one of which winters in 

 the larval state. 



The Japanese Beetle was accidentally introduced into New 

 Jersey from Japan about twenty years ago and since has spread 

 rapidly through many of the eastern States, defoliating trees and 

 shrubs and destroying lawns and golf greens. The larva spends the 

 winter underground and the adult emerges the following summer. 



It seems safe to say that the destruction wrought by the Cotton 

 Boll Weevil exceeds even its notoriety. During the first thirty- 

 five years after its invasion of the United States from Mexico, it 

 had to its account a wastage of upward of three billion dollars, 

 not to mention other immense financial losses due to depreciated 

 land values, etc. Probably each person in the United States pays 

 annually ten dollars more for cotton fabrics than he would if this 

 weevil did not exist. The injury to the Cotton plant is caused 



