INSECT ENEMIES OF WESTERN FORESTS 



137 



often bring about the death of the trees. Trees may harbor succes- 

 sive broods of these insects for a number of years before being killed. 

 Much damage is caused by the wind breaking off the infested stems 

 of young trees within 3 feet of the ground. The winter is passed by 

 the very young larvae in the bark, and pupation occurs the following 

 July. Damage in plantations can best be reduced by growing trees 

 on good sites. 



The poplar borer {Saperda calcarata Say) (4-5) breeds in felled and 

 weakened aspen and poplar throughout most of the United States. 

 The adults are elongate, robust, grayish beetles about 1 inch in 

 length, with faint yellowish spots on the elytra, and the antennae are 

 as lone: or lono-er than the 

 body. Emergence of the 

 adults occurs late in July 

 and in August. The female 

 chews a slit in the bark, in 

 Avhich one or two eggs are 

 deposited. The young lar- 

 vae mine into the bark and 

 remain there over winter. 

 They enter the sapw^ood 

 and heart wood the follow- 

 ing spring, where they feed 

 for 2 years. During this 

 time an opening is main- 

 tained through the bark 

 Avhere 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 follow- 

 ing spring. In July of the 

 third year the adults 

 emerge through the holes 

 used by the larvae for ex- 

 pelling frass. 



The amethyst cedar borer, {Hylotrupes) HeTnicallidium amethysti- 

 num Lee, attacks western red cedar, incense cedar, and juniper; and 

 although it usually selects injured or dying trees, it sometimes ap- 

 pears responsible for killing healthy trees. The adults are black, 

 over 1 inch in length, and have violet or bright-blue wing covers. 



Other species of bark-boring roundheaded beetles are as follows : 



Species Hosts and distribution 



Atimia dorsaUs Lee Cypress, juniper, and incense cedar. Western 



States. 



Semanotus ligneus F. var Juniper, cedar, big tree, redwood, hemlock, 



spruce, Douglas fir, balsam firs, larch, cy- 

 press, and pines. North America. 



Phymatodcs nitidns Lee Cypress, redwood, and cedar. Pacific coast. 



Lcpto-stylus nchulosus Horn Balsam firs. Oregon. 



Acanthochius ohliquus Lee Pines and spruce. Western States. 



Phymatodes decussatus Lee Oak. Washington. 



Figure 68. — Locust borer (Cyllene rohiniae) : A, 

 Adult, X 2.5 ; B, eggs, X 2.5 ; C, larva, one- 

 half natural size. (Drawing by Edmonston.) 



