256 



WEST VIRGINIA EXPERIMENT STATION 



ber beetles, which excavate galleries in the wood for the pur- 

 pose of depositing their eggs and rearing their young; also wood 

 boring grubs which hatch from eggs deposited in the outer bark 

 by adult beetles and wood wasps. As a rule, these wood borers 

 contribute very little towards the unhealthy condition or death 

 of the trees infested by them, but are exceedingly destructive 

 or detrimental to the wood of living, dying, or dead trees and 

 saw logs and the loss of timber resulting from their depreda- 

 tions is far greater than is generally supposed. 



TIMBER, OR AMBROSIA BEETLES. 



Among the wood miners, some of the most destructive kinds 

 belong to an interesting class called timber beetles, or ambrosia 

 beetles. These belong to. the same family as the 

 bark beetles, but instead of mining beneath the 

 bark and gnawing the outer surface of the wood, 

 they burrow directly through the bark into the 

 sapwood where they excavate their branching 

 egg or brood galleries. One species of this class 

 of miners is exceedingly common in the sapwood 

 f 8 P ruce trees and logs, which deserves special 



Spruce Timber rn ant inn 



Beetle. (Xyi- mention. 



oterus lineatus, 

 Ratz.) 



THE SPRUCE TIMBER BEETLE. 



This wood miner is distinguished from all other species of 

 similar form and habits, whcih infest the spruce, by its striped 

 wing covers. The adult is .13 inches long, 

 and .06 inch wide, the male with a narrow 

 concave head and the female with a large 

 head, which is convex in front. The eyes are 

 double, as in the destructive spruce bark bee- 

 tle. It passes the winter in all stages within 

 the brood chambers, and the adults emerge 

 in the spring and fly to the trunks and stumps Fig. xxx. work of 



Ambrosia Beetle (Xyl- 



of recently felled trees, or those seriously in- oteru* uneatw, Ratz). 

 jured by insects or other causes. They bore directly through 



1 Xyloterus lineatus, Ratz. 



