Fig. 15. 



Work of Ips balsameus in Abies, showing the wood surface scored by 



the chambers, egg-tunnels, larval galleries, and pupal cells. The 



latter are often sunken as indicated at "p.c." The work of 



Monohammus marmorator, which was bred from that 



trunk, is shown at " M.m." 



[90] 



