No. 4.] THE ELM-LEAF BEETLE. 293 



is readily attacked and severely injured. At Groton, last 

 summer, num])ers of large American elms were so severely 

 injured that they were as brown as if scorched by fire. At 

 Springfield several American elms that were stripped three 

 years in succession are now in a dying condition. Dr. Felt 

 states that the Scotch elm also suffers seriously from the 

 attacks of this insect. 



Nature of the Dainage. — The first injury to the tree is 

 caused by the attack of beetles on the leaves. Later the 

 larvse destroy the epidermis, the leaves turn brown, die and 

 fall, and the tree is left bare until a second crop of leaves 

 is thrown out. Frequently these leaves are in turn destroyed 

 by the later brood of larvae. The effect upon the tree is 

 shown ])y the gradual death of the smaller branches, and of 

 the entire tree in cases of severe and continued stripping. 

 City trees, through ignorant or careless treatment, commonly 

 suffer from lack of food and water supply, due to the cut- 

 ting off of roots to make room for curbinos and water and 

 gas mains. Such trees have but little reserve vitality, and 

 are easy victims to damage by the beetle. The weakened 

 condition of trees defoliated by the elm-leaf beetle invites or 

 favors attack by other insects, notably borers, bark beetles 

 and the elm-bark louse. 



Natural Enemies. 

 Several species of predaceous beetles are known to attack 

 this insect. In Massachusetts two species of soldier bugs 

 {Podisus serieventins and P. placidus) are its most common 

 enemies. These beneficial little bugs frequent the infested 

 trees and prey upon the larva3 and pupse.* 



Remedies. 

 In combating the elm-leaf beetle the chief reliance should 

 be placed upon the use of arsenical insecticides, and of these 

 the most satisfactory is arsenate of lead, which should be 

 used at the rate of five to ten pounds (actual arsenate of 

 lead) to one hundred and fifty gallons of water. Its prepa- 

 ration and application are discussed on another page. 



* At Squantum, July 12, a third species of predaceous bug (Siiretrus a7ichorago) 

 was found feeding upon the larvae of the elra-leaf beetle. 



