94 



MISC. PrBLICATlOX 273, U. S. DEPT. OF AGRICULTURE 



The elm leaf beetle {Galerucella xanthomelaena Sclirank) { = G. 

 luteola Mull.) is an introduced pest which has proved to be very 

 destructive to elms. Since 1834 it has gradually extended its range 

 to include nearly all parts of the country where elms are grown. 

 Trees are weakened and subject to attack by various boring insects 

 or are killed outright by repeated defoliations. The adults are one- 

 fourth inch in length and dull olive green with a black stripe on each 

 elytron. The larvae are blackish yellow and about one-half inch long 

 when full grown. Park and shade trees can be protected by spraying 



with arsenicals soon 

 after the new leaves 

 open in the spring. 

 The western wil- 

 low leaf beetle {Ga- 

 lerucella decora Say) 

 is a dull, yellow- 

 brown to black na- 

 tive species that feeds 

 on the leaves of wil- 

 low a n d p o p 1 a r 

 throughout the 

 country. 



The Cottonwood 

 leaf beetle, (Lina) 

 Ohrysofjiela script a 

 F. (fig. 47), is found 

 throughout the 

 country, feeding on 

 the leaves of willow 

 and poplar. In New 

 York it is very de- 

 ^^ -aw^^raj-^^^j^v structive to willows 



-^^ ' ^^^^^^^isx raised for basket- 



work, and often 

 heavily defoliates 

 these trees in the 

 West, The aduhs 

 are yellowish marked 

 with black spots and 

 are about one-fourth 

 inch in length. They 

 appear early in the spring and feed on the tender shoots. The eggs 

 are yellowish or reddish and are deposited in clusters on the under 

 surface of the leaves, and it is here that the black grubs feed as soon 

 as hatched. The period of growth to the mature larval stage is about 

 15 days in hot weather. Five generations a year are reported in the 

 West. C. tremulae F. feeds on aspen and poplars in the Pacific 

 Northwest. 



The willow leaf beetle {Chrysomela interrv.pta F.) is similar to the 

 above, but smaller. It feeds on willow and ranges from California to 

 Alaska. Another species, C. califomica Rogers, is black to bluish 

 green and feeds on willow in California. 



The spotted willow leaf beetle {Chrysomela lapponica L.) is some- 

 times as prevalent and just as injurious to willows and poplars in the 



Figure 47. — Cottonwood leaf beetle {Chrysomela scripta) : 

 A, Female beetle, X o ; B, male beetle. X o ; C, larva 

 X 5 ; D, pupa, X o ; E, eggs on cottonwood leaf ; F 

 skeletonized willow leaf. 



