246 



WEST VIRGINIA EXPERIMENT STATION 





as a large number of living spruce trees infested by this insect 



which were examined during a tour of 

 investigation through the spruce forests 

 in 1892, left no donbt whatever of its 

 power of entering and mining through 

 the healthy bark of vigorous* living 

 trees* or of its being the primary cause 

 of the death of the timber. I also 

 found it attacking and killing Norway 

 spruce in Morgantown, and found it in 

 abundance in a dying spruce (See Fig. 

 XXIII) in Washington, D. 0., in Oct., 

 1892. A full description and illustration 

 of this remarkable insect and its work, 

 and a detailed account of its life his- 

 tory and habits will be found in an- 



P art f this 



Fig.XXIII^Galleriesof Dentroc 



tonus frontaiis in spruce. Enemies of the Fine." 



THE DESTRUCTIVE SPRUCE BARK BEETLE. 1 



This is a small black beetle, .08 of an inch long and .1 of an 

 inch broad. It is easily distinguished from all other spruce 

 bark beetles of similar size and form by the fact that each of 

 its compound eyes is divided by a smooth narrow space. 

 It passes the winter in all stages within the bark of spruce 

 stumps, logs, and tops of trees cut the previous winter or 

 summer; also in the bark on all parts of such standing trees as 

 may have died during the previous spring or summer. The 

 adults emerge in May and June, and are attracted to the 

 stumps, trunks and tops of recently felled trees and such trees 

 as are weakened in vitality from the attack of insects like that 

 of the destructive pine bark beetle, diseases or any other 

 cause. They then commence to excavate their entrance gal- 

 leries through the outer bark, their presence being indicated by 

 the fine brownish borings in the crevices of the bark. This en- 

 trance gallery is extended to the outer surface of the inner soft 



1 Polygraphs rufipennis, Kirby. 



