98 



THE SCOLYTID BEETLES. 



METHODS OF CONTROL. 



Whenever it is positively determined that this species is attacking 

 Hving pine timber in a given locaUty and that the bark of Hving and 

 dying trees contains hving parent adults or developing broods, active 

 and radical measures should be promptly adopted for its control. 



The simple removal of the infested bark from the main trunks of the 

 trees, without burning it, is sufficient to kiU the broods of this species, 

 provided the work be done between the first of October and the first 



of June. If, in the case of a mod- 

 erate outbreak, the larger clumps or 

 patches of infested trees and the more 

 accessible scattering ones in the worst 

 affected sections of a forest are thus 

 treated, it should serve to bring the 

 pest under control the first year, but 

 in the case of a very extensive out- 

 break this may require two or three 

 years or more. 



If all of the infested trees can be 

 barked or utihzed and the slabs 

 burned without much additional ex- 

 pense, it may be best to do so, but 

 where, for any reason, this can not 

 be done within the specified time, the 

 work should be planned so as to in- 

 sure the barking or utihzation of all 

 of those in the larger patches, or an 

 aggregate of 75 per cent of the in- 

 fested trees to each square mile. 



If the bark be removed from 

 the standing trees (figs. 57, 58), an 

 aggregate of 75 per cent or more of 

 the actually infested bark should 

 be removed from all of the trees, 

 or all of the infested bark should be 

 removed from 75 per cent of the 

 trees. The work should he planned 

 and conducted with the object of destroying the greatest possible number 

 of insects for the labor and time expended. That is, if there are more 

 infested trees than can be barked within the specified time, and five 

 or six times as many insects can be killed by removing half of the 

 infested bark from the standing trees as can be done in the same time 

 by f elhng one tree and removing all of the bark, the former is far pref- 

 erable, remembering that it is not necessary to exterminate the enemy, 



Fig. 57. — Removing bark from trunk of 

 standing tree with special barking tool 

 having handles of different lengths, 

 to destroy broods of the Black Hills 

 beetle. (Original.) 



