INSiECT ENEMIES OF WESTERN FORESTS 



93 



common occurrence. Most of these beetles belong to the family Chry- 

 somelidae. The adults of this large family of destructive beetles are 

 small, rather short, somewhat oval in outline, and of variegated 

 colors, some with bright metallic green or blue and others dull brown 

 or black. The larvae are rather stout, humpbacked grubs. Some 

 are armed with spines, while others partially cover themselves with 

 excrement. In western forests the alder flea beetle is probably the 

 most conunon repre- 

 sentative of this 

 family. 



No control appears 

 practical or war- 

 ranted under forest 

 conditions, but o n 

 park and shade trees 

 leaf beetles c a n be 

 controlled by spray- 

 ing with powdered 

 acid lead arsenate at 

 the rate of 4 pounds 

 to 100 gallons of 

 water. The spray 

 should be applied as 

 soon a s t h e leaves 

 unfold in the spring. 



The alder flea bee- 

 tle {Altica himar- 

 ginata Say ) ( fig. 46 ) 

 is a native species 

 found throughout 

 the Pacific Coast 

 States, where it feeds 

 on and skeletonizes 

 the foliage of alder, 

 poplar, and willow, 

 both as larvae and as 

 adults. The adults 

 are small, dark shiny 

 blue, and about one- 

 fourth inch long. 

 The mature larvae 

 are a trifle over one- 

 fourth inch in length, dull brown to black, with shining black head 

 and thorax and three pairs of short legs. The adults hibernate dur- 

 ing the winter in debris beneath the trees and other sheltered places, 

 appearing early in the spring to resume feeding. Clusters of yellow 

 eggs are deposited sometime after the spring appearance of the 

 adults. The larvae, Avhich appear a few days later, reach maturity in 

 August, and pupation occurs on the ground in the duff. New adults 

 appear in a week or 10 days and feed voraciously on the foliage until 

 the close of the season, when they hibernate for the w^inter, to appear 

 the following spring, completing the cycle of one generation a year. 



Figure 46. — Alder flea beetle ( Altica timarginata) : A, Adult 

 beetle, X 4 ; ^, eggs, X 4 ; C;, larva, X 4 ; I>^ pupa, X 4 ; 

 E, skeletonized leaf. 



