21 



pine-bark beetle a of the middle Appalachian region and the spruce- 

 destroying beetle b of the Northeast, will warrant, it is believed, some 

 suggestions for the prevention of losses. 



METHODS OF COMBATING THE ENEMY AND PREVENTING LOSSES FROM 



ITS RAVAGES. 



When a trouble has been going on six or seven years and has 

 reached the magnitude of the one under consideration, it is very plain 

 that unless some natural agencies appear to either modify or check it, 

 its control is be}^ond all human effort. On the other hand, if there 

 are beneficial influences at work which are reducing the numbers of 

 the insect and checking its destructive ravages, there is much that can 

 be done toward aiding nature in the suppression and subjugation of 

 an unruly species. The evidences found indicate that the latter is true 

 in regard to this trouble. While many freshly attacked living trees 

 and thickly infested dying ones were observed in different sections- of 

 the reserve, showing that great numbers of the beetles are at work 

 and continuing the trouble, it was plain that the force of the attack 

 has from some cause been materially weakened. 



TO REDUCE THE NUMBERS. 



It appears that the pine-destroying beetle of the Black Hills, like 

 its Eastern relatives, depends on the trees killed by it for the aug- 

 mentation of its numbers and the perpetuation of its power of killing 

 more trees. Therefore it is only necessary that the attacking force be 

 further reduced to a point where it can no longer overcome the vital 

 resistance of the trees on which it concentrates its attack, in order to 

 successfully defeat it and secure its extermination. 



The fact that the attacking force of the enemy is already weakened 

 from natural agencies suggests that they can be reduced by artificial 

 means below their power of killing more trees next season, and thus 

 bring the trouble to an end. Therefore the following are suggested 

 and recommended as probably the best methods of accomplishing this 

 result: 



(1) Determine the location and extent of areas in which trees were 

 attacked during the summer and fall of 1901 and the number of trees 

 now infested with living broods of the pine-destroying beetle. 



(2) Select those areas in which there are the largest number of 

 infested trees and mark the same for cutting. 



(3) Secure, by sale contracts or otherwise, the cutting of these trees 

 and the removal of the bark from the infested parts of the main trunks 

 and stumps prior to the 1st of May, 1902. The drying of the removed 



a Dendroctonus frontalis (Zimm. ) var. destructor Hopk., Bui. 56, W. Va. Agric. Exp. 

 Station, 1899. 



b Dendroctonus piceaperda Hopk., Bui. 28 n. s., Div. Ent., U. S. Dept. Agric, 1901. 



