THE GENUS DENDROCTONUS. 35 



the beneficial insects will escape. Or, if it is not necessary to burn 

 the bark, practically all will escape, and thus assist in destroying the 

 broods left in the tops of trees and those in scattering trees. It is 

 always important, therefore, to determine whether or not the natural 

 enemies are present in sufficient numbers to make it worth while to 

 adopt special precautions for their protection. 



Wherever woodpeckers are common in a forest they may aid greatly 

 in destroying the broods of barkbeetles in the scattering clumps and 

 isolated trees, especially if the beneficial insects are scarce. If, on 

 the other hand, the beneficial insects are common, the birds may 

 feed on them and do as much harm as good. The protection of the 

 birds, however, should be maintained, because even if they are harm- 

 ful at times they evidently more than compensate for it in the general 

 service they render to the forest. 



IMPORTANCE OF SYSTEMATIC FORESTRY. 



After all, success in the control of these beetles and of forest insects 

 in general depends more upon good forest management, perhaps, 

 than upon anything else relating to the practical phases of the 

 problem, for without some organized system of management very 

 little can be accomplished toward the successful utilization of avail- 

 able information or methods of control. It is equally true, however, 

 that imless the available knowledge relating to the insects and the 

 principles of their control is understood and properly utilized in 

 forest management and lumbering operations, nothing will be ac- 

 complished, and the depredations and great losses of valuable timber 

 will continue. 



SOME RESULTS OF EFFORTS TO CONTROL BEETLE DEPREDA- 

 TIONS. 



It is only within recent years that any detailed work has been done 

 on the forest insects of North America, and the possibility of con- 

 trolling their depredations is not generally recognized, even among 

 foresters. Organized efforts and definite results were not, therefore, 

 to be expected, yet we have a few examples which may serve as 

 demonstrations of what can be done. In 1900 the eastern spruce 

 beetle was killing a large amount of mature spruce in northwestern 

 Maine. This was investigated and the concentration of the logging 

 operations in the infested sections was recommended. This recom- 

 mendation was adopted, and with little or no additional expense 

 sufficient numbers of the infested trees were cut the first winter, and 

 the logs floated out in the spring, to check the ravages of the beetles, 

 and, so far as can be learned, up to the present time very little timber 

 has since died in that section as the result of insect attack. 



