INSECT 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 common repre- 
sentative of this 
family. 
No control, appears 
practical or war- 
ranted, under forest 
conditions, but on 
park and shade trees 
leaf beetles can 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 as the leaves 
unfold in the spring. 
The alder flea bee- 
tle (A ltica bimar- 
ginata Say) (fig. 46) 
is a native species 
found throughout 
the Pacific Coast 
States, where it feeds 
on and _ skeletonizes 
the fohage of alder, 
poplar, and willow, 
both as larvae and as 
adults. The adults 
are small, dark shiny ieee 
blue, and about one- ie 
fourth inch long.  Ficurw 46—Alder flea beetle (Altica bimarginata) : A, Adult 
vitomminamie larvae! Net crciecénizel iat 2? PUPA SS 
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 
egos are deposited sometime after the spring appearance of the 
adults. The larvae, which 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 winter, to appear 
the following spring, completing the cycle of one generation a year. 
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