INSECT ENEMIES OF WESTERN FORESTS 125 



of growth to the mature larval stage is about 15 days. Five gener- 

 ations a year are reported in the West. C. tremulae F. feeds on 

 aspen and poplar in the Pacific Northwest and in the East. 



The willow leaf beetle (Chrysomela interrupta F.) is similar to 

 the above, but smaller. It feeds on willow and ranges from Cali- 

 fornia to Alaska and eastward. Another species, C. calif ornica 

 Rogers, is black to bluish green and feeds on willow in California. 



The spotted willow leaf beetle (Chrysomela lapponica L.) is 

 sometimes as prevalent and just as injurious to willows and pop- 

 lars in the Northwest as the cottonwood leaf beetle, which it 

 closely resembles in appearance and habits. The adults are reddish, 

 14 inch long, and spotted with black. 



On coniferous trees colorful, squarish scarabaeid beetles of the 

 genus Dichelonyx are commonly found chewing scallops along the 

 edge of needles. D. crotchi Horn is a shiny green beetle about % 

 inch long, which bites into the sides of ponderosa, Jeffrey, and 

 lodgepole pine needles when they are about 1 inch long, causing 

 them to drop. It is found in the mountains of California, Oregon, 

 Washington, and British Columbia and eastward into Utah and 

 Montana. D. decolorata Fall feeds on the needles of Monterey pine 

 in California. D. valida Lee. is a dark blue-green species found 

 on California laurel along the Pacific coast. D. testaceipennis Fall 

 is a shiny brown species, the individuals of which feed close to- 

 gether on needles of white fir, Douglas-fir, and other forest trees 

 in New Mexico. 



Adult weevils of the genus Scythropus are often found feeding 

 on pine needles in the spring and early in the summer. They bite 

 out chunks and leave a saw-toothed edge. They are from % 6 to 

 % 6 inch long and range in color from metallic bluish-green and 

 gray to bronze, copper, or dark brown. The elegant pine weevil 

 (S. elegans (Couper)) is a metallic blue-green, gold, brass, or 

 bronze species sometimes with lighter stripes along the margins 

 of the wing covers. It feeds on lodgepole and other pines in the 

 northern Rocky Mountain region and in other Western States. 

 S. calif ornicus Horn is a bronze species somewhat speckled with 

 gray, found on ponderosa, Jeffrey, digger, and other pines 

 throughout the Pacific Coast States and the Southwest. S. ferru- 

 gineus Csy. is a metallic, reddish-bronze or copper-colored species, 

 which is found on ponderosa, Jeffrey, knobcone, and Monterey 

 pines in California and Oregon. S. albidus Fall is a small ashy- 

 white weevil with a faint metallic lustre, which occurs on pon- 

 derosa and Jeffrey pines in California, Oregon, and Idaho. 



Another small leaf weevil, Thricolepsis inornata Horn, 3/ ]6 inch 

 long, is mottled black and gray. Normally it feeds on oak, but 

 sometimes nearly defoliates fruit trees close to oaks by feeding on 

 the new leaves of opening buds. Adult weevils have been found 

 seriously injuring tender new foliage on tips of white fir and 

 Douglas-fir in New Mexico and southern California, ruining such 

 trees for use as Christmas trees. It is distributed through Oregon, 

 California, Utah, Arizona, and New Mexico. 



