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



trees. These belong to the same genera that are met with in pines 

 and firs. 



The Sitka spruce engraver {Ips condnnus Mann.) attacks the 

 bark of living, dying, or felled Sitka spruce along the coast of 

 Oregon and northward to Alaska. No reports have been received 

 of its having done more than nominal damage. The adults are about 

 one -eighth inch long, with three teeth, one very prominent and two 

 smaller, on each side of the concave elytral declivity. They excavate 

 an irregular central nuptial chamber, with three or four short curved 

 or S-shaped galleries radiating therefrom. Four eggs are laid in 

 each egg pocket and the four laval mines issuing from each pocket are 

 a characteristic feature of its work. (See p. Ill for a general discus- 

 sion of the work and habits of the Ips beetles.) 



Other species of Ips which attack spruce include the following: 



Species of Ips Host and distribution 



/. perturbatiis Eichh White spruce. Northern Canada and 



Alaska. 

 /. interpunctus Eichh Wliite spruce and Engelmann spruce. 



Alaslca, Yulvon. and British Columoia. 

 /. interniptus Mann Sitl^a spruce, white spruce. Oregon to 



Alaska and eastward. 

 /. diihius Sw Engelmann spruce. British Columbia 



and Rocky Mountain region. 

 /. tridens Mann Engelmann spruce, Sitka spruce, and 



probably white spruce. Canadian 



Rockies and British Columbia. 

 /. engelmanni Sw Engelmann spruce and white spruce in 



same region. 

 /. yolioensis Sw Engelmann spruce and probably white 



spruce. British Columbia. 



The Sitka spruce hylesinus {Pseud ohylesinus sitchensis Sw.) is a 

 small, densely scaly, suboval bark beetle which is found attacking 

 felled or dying Sitka spruce in British Columbia, Washington, and 

 Oregon. 



Scierus annectens Lee, a small reddish-brown bark beetle about 

 one-eighth inch long, attacks white spruce, Engelmann spruce, lodge- 

 pole pine, and probably Sitka spruce in western Canada and the 

 Northwestern States. 



Dryocoetes affaber Mann, attacks the tops of felled and dying 

 Sitka spruce, Engelmann spruce, and Douglas fir from Alaska south- 

 ward into the Northwestern States. The adults, which are less than 

 one-eighth inch in length, construct irregular, short ^gg galleries. 



Dryocoetes confusus Sw. (p. 125) may also be found attacking and 

 sometimes killing Engelmann and other spruces. 



HEMLoqK Baek Beetles 



"While hemlocks have a number of bark-beetle enemies, these are 

 mostly of secondary importance, and seldom are any large number 

 of trees killed. 



Western hemlocks {Tsuga heferopliylla) are sometimes attacked 

 and killed by the Douglas fir beetle (p. 120) when associated Avith 

 Douglas fir. At times weakened trees are attacked by species of 

 Scolytus and PseudoMjIe sinus. 



Mountain hemlocks, when in mixture with loclgepole pine, are 

 sometimes killed by the mountain pine beetle (p. 102), but are most 

 frequently attacked by a species of Scolytus. 



