126 MISC. PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 
spruce beetle, become exceedingly destructive at times. Young trees 
are sometimes killed by species of Zps, Pseudohylesinus, and Dry- 
ocoetes, and by other ena engraver beetles. 
FIGURE 63.—Galleries of the western balsam bark beetle, Dryocoetes confusus. 
The Englemann spruce beetle (Dendroctonus englemanni Hopk.) 
has caused widespread destruction of mature Englemann spruce in | 
the Rocky Mountain region and is considered a very important 
