INSECTS IN RELATION TO MAN 419 



1916, and in Pennsylvania in 1920. It came from Japan probably as 

 f grubs in soil about the roots of iris or azalea plants, but brought none of 

 its native enemies with it, and spread rapidly in its new environment. 

 In 1921 it occupied two hundred and thirteen square miles in New 

 Jersey and fifty-seven in Pennsylvania. 



The injury is done mostly by the beetles, which skeletonize the leaves 

 of trees and shrubs, both wild and cultivated, destroy ripening fruits, 

 and have a longer list of food plants than the brown-tail moth. 



Extensive operations against the beetle are being conducted by the 

 Bureau of Entomology in co-operation with the Departments of Agri- 

 culture of New Jersey and Pennsylvania. 



The elm leaf beetle (Galemcella luteola), notorious in southern 

 Europe as a defoliator of elm trees, entered Maryland about 1837, 

 spread along the coast as far as southejn New Hampshire, and has made 

 its way into New York, Ohio and Kentucky, killing off thousands of 

 fine old elms on its way. The only effective means of controlling this 

 beetle seems to be an arsenical spray. 



The leopard moth (Zeuzera pyrina) , another European species acci- 

 dentally introduced into New Jersey some time before 1879, spread north 

 into Massachusetts, assisting the elm leaf beetle in its injurious activity. 

 The leopard moth is not confined to elms, however, though it injures 

 chiefly elms and silver maples, but attacks more than eighty kinds of 

 trees and shrubs, and affects fruit trees as well as shade trees. The cater- 

 pillar does not feed on the leaves but bores into the branches, which 

 become weakened as a result and are broken off by the wind. 



The pink bollworm (Pectinophora gossypiella) , a cotton pest which is 

 probably a native of southern Asia and occurs also in Africa, Hawaii 

 and Brazil, entered Mexico and was recently introduced into Texas. 

 This serious pest is now being eradicated by the Department of Agri- 

 culture, at an annual expense of about half a million dollars. 



An insect often passes readily from a wild plant to a nearly related 

 cultivated species. Thus the Colorado potato beetle passed from the 

 wild species Solanum rostratum to the introduced species, Solanum 

 tuberosum, the potato. Many of our fruit-tree insects feed upon wild, as 

 well as cultivated, species of Rosaceae; the peach borer, a native of this 

 country, probably fed originally upon wild plum or wild cherry. Many 

 of the common scarabaeid larvae known as ''white grubs " are native to 

 prairie sod, and attack the roots of various cultivated grasses, including 

 corn, and those of strawberry, potato and other plants. The chinc'h 

 bug fed originally upon native grasses, but is equally at home on cul- 



