INSECT ENEMIES OF WESTERN FORESTS 



197 



tion into sound wood. The larvae are creamy-white and about 1 

 inch long when full-grown. The adults are dark brown to black 

 with various yellow markings. They have also been found work- 

 ing in redwood, Sitka spruce, western hemlock, and other conifers 

 in the Pacific Coast States. 



Long-horned beetles of the genus Xylotrechus are stout and 

 cylindrical, with antennae only slightly longer than the head and 

 thorax and with wavy, zigzag, or crescent-shaped markings across 

 the wing covers. The larvae of X. undulatus (Say) bore in Doug- 

 las-fir, larch, spruce, and hemlock in the Pacific Coast and northern 

 Rocky Mountain States. The adults are from y 2 to % inch long 

 with black, sharply outlined white markings on the wing covers. 

 X. abietis Van D. is similar to the above with more indistinct 

 smoky-white markings. The larvae bore in the true firs. X. nauti- 

 cus (Mann.) (fig. 94, A) is a dark-brown beetle with lighter 



A 



B 



Figure 94. — Roundheaded wood borers: A, Xylotrechus nauticus, 

 B, Neoclytus conjunctus, X 2. 



markings and is from y 2 to % inch long. The larvae commonly 

 bore in oak and madrone, especially in firewood, in California, 

 Oregon, and eastward into Montana. X. insignis Lee. is a velvety- 

 brown beetle with bright yellow markings and is y 2 to % inch 

 long. The larvae bore in willow in California, Oregon, Nevada, and 

 Arizona. X. annosus (Say), a gray species with white markings, 

 breeds in aspen, poplar, and willow in the Rocky Mountain and 

 Pacific Coast States. X. obliteratus Lee. is a serious pest of aspen 

 and poplar in the Rocky Mountain region. The larvae work under 

 the bark and into the wood, especially at the base of trees, and 

 attacks are repeated until the heartwood is completely honey- 

 combed and the trees break off during wind or snow storms. Ex- 

 tensive areas of aspen above 7,000 feet in Colorado and Utah have 

 been killed by this species. The adults are from y 2 to % inch in 

 length, and are dark with three yellow bands across the wing 

 covers. 



Other species of wood-boring cerambycids that may be encoun- 



