122 THE SCOLYTID BEETLES. 
followed by the lateral extension of the larval mines of the young 
broods, which serves to completely girdle the tree and kill the inner 
bark, and this in turn is followed some months later by the gradual 
or sudden dying of the leaves and the complete death of the tree. 
The trees on which a successful attack is made in June or July will 
have the leaves faded and fallen by October, but the leaves on those 
attacked in August or later may remain normal until the following 
May or June before the}' fall. 
EXTENT OF DEPREDATIONS. 
The evidence we have been able to collect shows that at various 
times during the past century this beetle has been the cause of the 
death of an enormous amount of the best matured spruce timber in 
the forests from New Brunswick to northern New York and in places 
in Canada. It is also evident that it will continue to be a menace to 
standing matured timber, probably throughout the region in which 
the red and white spruce prevail in forest growth. 
In a report by C. W. Johnson (1898, pp. 73-74), reference is made 
to extensive destruction of red spruce in the mountains north of Stull, 
Wyoming Count}", Pa., supposed to have been caused by a Dendroc- 
tonus identified as D. rufipennis. Specimens collected by Mr. Johnson 
have been examined by the writer and found to be D. piceaperda. 
Mr. Johnson stated that some 5,000,000 feet of spruce had been killed 
on the lands of one company, apparently during 1896 and 1897. 
EVIDENCES OF ATTACK. 
The first evidence of attack on living trees is reddish boring dust 
lodged in the loose bark and moss on the trunk and around the base 
of the tree, or numerous fresh gum spots or pitch tubes mixed with 
whitish or reddish borings on the bark of the middle or lower portion 
of the trunk. TThen this is found it will indicate that the beetles 
are actively at work excavating the galleries in the bark. After this 
work is completed and the broods of larvae have killed the inner bark 
the pitch tubes have an old or dried appearance and the boring dust 
is less evident. By the time the larva? have developed and trans- 
formed into pupae and adults during September and October the 
infested trees are indicated by the faded pale-green appearance of the 
needles on the trees or on the ground, and by the reddish appearance 
of the tops from which the needles have recently fallen. During the 
winter and following spring the trees that were attacked later in the 
preceding summer will present the same evidence of infestation, and 
in addition a large percentage of the infested trees are usually marked 
by woodpecker work. The birds discover the broods of beetles and 
larvae, and in their efforts to get the insects they remove a sufficient 
amount of the outer loose bark to give the trunks a conspicuously 
