INSECT ENEMIES OF WESTERN FORESTS 



195 



Figure 92. — The black-horned pine borer (Callidium antennatum) : A, 

 Larvae; B, pupa; C, adult; D, larval damage to pine board where bark 

 edging remains. 



perum Casey) (121) (fig. 92) is a common species in western 

 forests, attacking the logs and limbs of dead ponderosa pine, sugar 

 pine, and Douglas-fir. It attracts attention occasionally as a de- 

 structive borer in lumber stored in mill yards, where it attacks 

 strips of bark left on the edges of lumber stock. The larvae work 

 under this bark and score the surface of the wood, then extend 

 their mines into the sapwood for a depth of 2 or 3 inches. They 

 also injure seasoned rustic work by mining out the cambium layer 

 and causing the bark to loosen from the log. The larvae are 

 yellowish-white, apparently legless grubs about % inch long 

 when full grown. The adults are flat, shining, bluish-black beetles 

 about y 2 inch long, with antennae about half as long as the body. 

 Other closely related species of Callidium attacking the limbs of 

 various firs, pines, cedars, redwood, and junipers are discussed 

 under the section on Twig Borers on page 47. 



Callidium pallidum Van D. has been reported as working in 

 the stumps of redwood in California. 



Arhopalus productus (Lee.) is a narrow black beetle about % 

 inch long. The white larvae mine under the bark and into the 

 sapwood and heartwood of fire-killed Douglas-fir, causing much 

 damage to the wood and often limiting its salvageability (96). 

 It is also found in pines throughout the Pacific coast and east- 

 ward into Montana. A. asperatus (Lee), a larger, more robust 

 species with roughened prothorax (fig. 93), does similar work in 

 true firs and spruce in the same regions. 



The black spruce borer (Asemum atrum Esch.) is the most 

 abundant species found attacking the heartwood of Douglas-firs 

 killed by fire, especially in the early years (96). The adult beetles 



