30 



This species is extremely abundant in Douglas fir slash throughout the parts 

 visited, and probably occurs throughout the range of its food-plant. Its normal 

 habit is to prefer dying bark, and to breed in the bark of trunks and larger branches 

 of injured and dying trees, and in stumps and slash from cuttings. Not rarely 

 it spreads to healthy timber and may become a more or less serious enemy. It 

 also breeds in British Columbia in the western larch. 



The adult is stout, reddish brown to nearly black, and 4 to 7 mm. in length. 

 The pronotum is broader than long, with the sides rounded and strongly narrowed 

 in front, irregularly punctured and hairy above. The elytra have long hairs 

 nearly to the base, with impressed striae of punctures and roughened interspaces. 

 It is readily distinguished from all other described species in British Columbia by 

 the straight parallel sides of its epistomal process, and, practically, by its occur- 

 rence in Douglas fir and western larch. 



Fig. 14. The Douglas Fir Bark-beetle. 



(Dendroctonus pseudotsugae Hopk.) 



Greatly enlarged. (Original). 



LIFE-HISTORY AND HABITS. The adults emerge from the old bark during 

 the spring and early summer and attack dying or healthy bark in pairs. They 

 enter usually through the thinner places, or bark fissures, and excavate elongate, 

 rather straight tunnels between the bark and wood surface, upward from the 

 entrance hole. The female deposits eggs singly in shallow niches cut in groups 

 alternately on the sides of the egg-tunnel and covers all with a laj r er of boring-dust 

 which later largely fills the egg-tunnels. The larvae cut their galleries through 

 the inner bark, away from the egg- tunnel, leaving the wide, long and often rather 

 straight larval galleries packed with concentric layers of reddish boring-dust. The 

 larvae enlarge the ends of the galleries to form pupal cells, either exposed in the 

 inner bark or in the middle layers, and there pupate. They emerge through 

 round holes cut through the outer bark during late summer, or hibernate beneath 

 the bark, either in the pupal cells or congregated in cavities caused by the 

 destruction of the inner bark. 



