INSECTS INJURIOUS TO TREES 141 



IMPORTANT INSECTS 



THE ELM LEAF BEETLE 



Life history: The elm leaf beetle, Fig. 100, is annually 

 causing the defoliation of thousands of elm trees throughout 

 the United States. Several successive defoliations are 

 liable to kill a tree. The insects pass the winter in the 

 beetle form, hiding themselves in attics and wherever 

 else they can secure shelter. In the middle of May when 

 the buds of the elm trees unfold, the beetles emerge from their 

 winter quarters, mate, and commence eating the leaves, 

 thus producing little holes through them. While this 

 feeding is going on, the females deposit little, bright yellow 

 eggs on the under side of the leaves, which soon hatch into 

 small larvae or grubs. The grubs then eat away the soft 

 portion of the leaf, causing it to look like lacework. The 

 grubs become full grown in twenty days, crawl down to the 

 base of the tree, and there transform into naked, orange- 

 colored pupae. This occurs in the early part of August. 

 After remaining in the pupa stage about a week, they change 

 into beetles again, which either begin feeding or go to 

 winter quarters. 



Remedies: There are three ways of combating this 

 insect: First, by spraying the foliage with arsenate of lead 

 in the latter part of May while the beetles are feeding, 

 and repeating the spraying in June when the larvae emerge. 

 The spraying method is the one most to be relied on in 

 fighting this insect. A second, though less important 

 remedy, consists in destroying the pupce when they gather 

 in large quantities at the base of the tree. This may be 

 accomplished by gathering them bodily and destroying them, 

 or by pouring hot water or a solution of kerosene over them. 



