162 THE SCOLYTID BEETLES. 
ditions the vast numbers of this insect which have bred in the in- 
jured and dying trees will, through necessity, attack the living trees 
and cause serious and widespread damage the first year. This will 
usually be followed by little or no damage in succeeding years, unless 
more favorable conditions are again presented for their multiplication. 
Unfavorable conditions for injury to living trees by this insect are 
found in healthy forests under a system of forest management which 
requires more or less continuous timber-cutting operations to utilize 
the older matured, injured, and dying trees. 
METHODS OF CONTROL. 
Owing to the peculiar habits of this beetle and the character of the 
injury caused by it, contrasting strongly with those of other species of 
the genus except the black turpentine beetle, the problem of control 
is quite different from that relating to nearly all of the other species. 
The principal injury is to the base of living trees, which, in itself, may 
be slight, but when aggravated and extended by subsequent and quite 
different causes may become quite extensive. Therefore the object 
should be to prevent the primary injury, by preventing the undue mul- 
tiplication of the beetle or by providing more attractive and con- 
tinued breeding places. The first may be accomplished within quite 
an extensive area if the infested bark is removed from the base of 
insect-killed, lightning-struck, and otherwise injured or dying trees, 
as well as from the stumps of local or sporadic timber-cutting oper- 
ations, the work to be done during the fall and winter following infesta- 
tion, beginning with the first of September and ending with the first of 
March. When only a few trees in a lawn or park are involved, or even 
where many are attacked in a forest under a complete system of forest 
management, serious injury may be prevented by cutting the beetles 
out of the bark with a chisel or knife, as soon as the discharge of resin 
on the bark indicates their presence. Often they can be killed quickly 
and effectually by means of a stout wire inserted into the entrance 
burrow, if done before the parent beetles have extended their galleries 
in the inner bark beyond 2 or 3 inches. 
It appears that continued timber-cutting operations offer sufficient 
and more attractive breeding places for this beetle. Therefore, in 
sections where these are carried on little or no damage to the living and 
otherwise uninjured trees will result ; but if the cutting should be dis- 
continued for one or more years throughout a large area the infested 
bark should be removed from the majority of the stumps of trees 
felled during the fall, winter, and spring, the work to be done during 
the fall and winter following the cutting. 
In case the removal of the bark from the stumps is required in 
timber-cutting contracts, it should be specified that the bark must 
not be removed until after it becomes infested with broods of larvae, 
