INSECTS AFFECTING PARK AND WOODLAND TREES 363 



entirely to the inner bark, but as it increases in size the sapwood may be 

 scored, and eventually the borer may go to some depth in the wood, 

 particularly on the approach of winter. 



This grub when near maturity is very strong and excavates large, 

 irregular galleries in almost any direction in the wood, and has been fre- 

 quently met with by the writer at the depth of 6 or 8 inches from the 

 surface. He has seen small balsam trees, 6 inches in diameter, penetrated 

 to the center by the grub, which subsequently completed its transformations 

 and the beetle emerged on the opposite side. This borer works so vigor- 

 ously that it may be heard at night gnawing in the wood. 



The period required for the completion of the life cycle is unknown, 

 though most writers are of the opinion that under ordinary circumstances 

 three years are necessary. Dr James Fletcher calls attention to the finding 

 of larva of all sizes in a pine which had been killed by fire the previous 

 spring and from this he is inclined to believe that under certain conditions 

 the life cycle may be completed in a year. It is known that this time may 

 be enormously extended, since beetles have been bred out from wood which 

 had been cut io to 15 or more years before. 



Distribution. This insect, which appears to have a general distribution 

 in pine, spruce and balsam regions, ranges from West Virginia into Canada 

 and, according to published accounts, it appears to be much more abundant 

 to the north. 



Protective measures. Very little, or nothing can be done to protect 

 standing trees from attack by this insect, other than the prompt cutting of 

 dying and dead timber. Dr James Fletcher has pointed out that logs may 

 be protected to a considerable extent by covering them with fir boughs so 

 as to shade them from the sun. Probably any other shade would be nearly 

 as effective. The removal of the bark would also aid materially in prevent- 

 ing the borers from entering the logs. 



Bibliography 



1857 Fitch, Asa. Ins. N. Y. 4th Rep't, p. 21-24 



1890 Packard, A. S. U. S. Ent. Com. 5th Rep't, p. 686-95 



