INSECT ENEMIES OP WESTERN FORESTS 



175 



Figure 81. — A, Larva and work of the ponderosa pine bark borer (Acan- 

 thocinus spectabilis) . The borings are shown crossing those of the western 

 pine beetle. Insert: B, Male beetle; C, female beetle. All natural size. 



aspen, poplar, cottonwood, and willows throughout most of the 

 United States. The adults are elongate, robust, grayish beetles 

 about 1 inch long, with faint yellowish spots on the elytra, and 

 the antennae are at least as long as the body. The adults emerge 

 late in July and in August. The female chews a slit in the bark, 

 in which she deposits one or two eggs. The young larvae mine into 

 the bark and remain there over winter. The following spring they 

 enter the sapwood and heartwood, where they feed for 2 years. 

 During this time they maintain an opening through the bark 

 where the eggs were laid, and through this boring dust is expelled. 

 When mature the larvae construct pupal cells near the lower end 

 of the larval mines, and in these they remain inactive until the 

 following spring. In July of the third year the adults emerge 

 through the holes used by the larvae for expelling frass. 



The amethyst cedar borer (Semanotus amethystinus (Lee.) ) at- 

 tacks California incense cedar, western redcedar, Port Orford 

 cedar, and probably other cupressine trees in California, Oregon, 

 Washington, and British Columbia. It usually selects injured or 



