25 



The tunnels of these species are found in the bark of the trunk and branches. 

 They are always abundant in slash, and sometimes enter trees in which the resin 

 is still fluid, so that gum-tubes are found about the tunnel openings. Several 

 species were working in the fading trees at Princeton this summer, and we may 

 yet find some of this genus acting as primary enemies in British Columbia. 



Fig. 11 Ips integer Eichh.; greatly enlarged, 

 (Original). 



