CONTROL OF TWO ELM-TREE PESTS 



GLENN W. HERRI CK 

 THE ELM LEAF-BEETLE 



(Galerucella luteola Mull.) 



The American elm is perhaps the greatest favorite among shade trees 

 in the United States. It is probably more widely planted for this purpose 

 than any other tree, especially in the eastern p^art of the country. Our 

 forefathers in New England, remembering their beloved English elms, 

 went into the woods, brought forth the slender, graceful young elms, 

 and set them in front of their homes and along their streets. As their 

 descendants marched westward they too remembered these fine trees 

 and followed the commendable example of their fathers. The fine trunk 

 of the elm, with its spreading branches terminating in graceful, pendulous 

 tips, makes it a very beautiful tree. There is no street more attractive 

 than an avenue almost arched with the mighty arms of the elms. 



It is a source of great regret that the American elm is subject to the 

 attacks of a most injurious insect pest, the imported elm leaf-beetle. 

 But fortunately this pest can be controlled if fought with vigor and 

 thoroughness. 



The imported elm leaf -beetle was abundant and injurious in Baltimore, 

 Maryland, in 1838. It must have come into the country about 1834. 

 Since that time it has gradually extended its territory until now it is 

 found as far north as Massachusetts and New York and as far west as 

 Ohio and Kentucky. In New York State it is destructive in the eastern 

 and central sections and will probably extend its activity gradually until 

 it covers the greater part of the State. 



Professor Slingerland 1 records the appearance of the beetle in Ithaca 

 for the first time in 1902. A student in Cornell University, P. B. Powell, 

 discovered the eggshells and the young and nearly mature grubs on July 

 13, 1902, on some elms along University Avenue, which leads to the Cornell 

 University campus. Apparently the infestation was light, for only a 

 few branches on a dozen trees were found affected. On July 16 beetles 

 were found, and on August 2 the beetles emerged from larvae collected 

 earlier. The beetles must soon have invaded the trees on the university 

 campus, and from that time until the spring of 1911 they steadily increased 

 in numbers and destructiveness. By 1911 the trees had begun to show 

 seriously the effects of the injury and a few had nearly succumbed. It 



1 Entomological News, vol. 14, 1903, p. 30. 



491 



