190 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



most frequently found breeding in the wood of forest trees are 

 the following: 



Species of Dicerca Hosts and distribution 



crassicollis Lee Douglas-fir. Pacific States. 



divaricata (Say) Alder, birch, and other broadleaved trees. Colo- 

 rado and Utah. 



horni Crotch Alder, sycamore, and other broadleaved trees 



and shrubs. Pacific States and northern 

 Rocky Mountains. 



prolongata Lee Aspen, cottonwood, poplars, alder, and other 



broadleaved trees. All Western States. 



sexualis Crotch Douglas-fir, ponderosa pine, Jeffrey pine, and 



knobcone pine. New Mexico, Arizona, Cali- 

 fornia, Oregon, and Washington. 



tenebrosa (Kirby) (fig. 88) . Pines, true firs, Douglas-fir, and Engelmann 



spruce. California, Oregon, Washington, 

 Idaho, Montana, and Eastern States. 



The western cedar borer (Trachykele blondeli Mars.) (23, 76) 

 mines in the sapwood and heartwood of living, dying, or dead 

 trees of western redcedar, cypress, California incense cedar, and 

 related species and is very destructive to trees used for poles, 

 shingles, cooperage, ship-building, or other purposes where sound 

 wood is required. The adults, which are roughly sculptured beetles 

 about % inch long, of a very beautiful, bright emerald green with 

 a golden sheen, lay their eggs on the wood of scars on the trunk or 

 branches of standing trees, and the flatheaded larvae mine about 

 in the wood for a period of 2 or 3 years before reaching maturity. 

 The newly formed beetles remain in the wood for about 6 months, 

 from September to May, before they emerge and start a new gen- 

 eration. There is no practical means of control under present 

 forest conditions. The variety of juniperi Burke is found in juni- 

 pers in California. 



Three other species of this genus are found in the Western 

 States doing similar work in various cedarlike trees: 



Species of Trachykele Hosts and distribution 



nimbosa Fall True firs and mountain hemlock. California, 



Oregon, Washington, Idaho, and British 



Columbia. 

 opulenta Fall California incense cedar, western redcedar, 



giant Sequoia, and related trees. California, 



Oregon, and Washington. 



There are 115 or more species of small flatheaded borers of the 

 genus Chrysobothris that bore in the bark and wood of limbs and 

 trunks of various weakened, dying, or dead conifers and broad- 

 leaved trees. Only a few of these are of sufficient importance to 

 warrant specific mention. The cedar flatheaded borer (Chryso- 

 bothris nixa Horn) is a common enemy of California incense 

 cedar, Sierra juniper, and cypress in the Pacific coast region. C. 

 californica Lee. works in the exposed roots of ponderosa and 



