144 



Bulletin 234. 



Fig. 35, — a, Tlic bronze birch borer beetle, nalitral size in lower corner; b, the 



grub or borer, natural size above. 



Fig. 36. — a. Portion of trunk of while birch with bark removed lo show how the 

 burrows of the borer sometimes zigzag across each other; b, shows a bur- 

 row extending through the wood; c, hibernating and transforming chambers 

 m the wood a short distance beneath the bark. All figures reduced slightly. 



