162 THE SCOLYTID BEETLES. 



ditions the vast numbers of this insect which have bred in the in- 

 jured and d}nng 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 larva?, 



