8 



BULLETIN 1490, U. S. DEPARTMENT OF AGRICULTURE 



beetles or timber worms. In the former case (where caused by am- 

 brosia beetles) the holes are made by both .the small, slender, cylin- 

 drical, adult beetles, and, after hatching within the wood, by their 



Fig. U. — Pinholes made by the spruce timber beetle {Xyloterus bivittatus) in red 



spruce. West Virginia 



larvae or young. In the latter case the injury is caused entirely 

 by the larvae or grubs (young) of beetles or the so-called timber 

 worms. 



