ADDITIONAL DATA ON THE LOCUST BOBEK. 39 



natural growth. It will be found, however, that no area of consid- 

 erable extent, even in such localities, is entirely free from this and 

 other destructive insect enemies, and that certain precautions and 

 well-planned methods of management with reference to the control of 

 the latter will be necessary. 



MANAGEMENT OF PLANTATIONS TO PREVENT INJURY. 



In the first place it is necessary, in order to provide against future 

 losses from the borer, that a thorough survey be made in May and 

 June, not only of the area to be utilized but of the entire neighbor- 

 hood for a radius of a mile or more from its borders, for the purpose 

 of locating and destroying scattering trees and groves which are more 

 or less seriously infested or damaged by the borer. It would seem 

 that the control of such large areas, bj^ purchase or under a plan of 

 cooperation between the owners of the land or trees, is one of the 

 most important requisites for success in preventing future losses from 

 the ravages of this and other insects in small as well as large planta- 

 tions. In fact, it is the writer's opinion that, with this precaution 

 properly and continuously carried out, locust may be successfully 

 protected from the borer in any locality. 



In the subsequent management of plantations and of natural forest 

 and sprout growth it is important each year to locate and destroy the 

 worst infested trees for the purpose of killing the borers in the wood, 

 and to conduct the thinning and commercial cutting operations during 

 the period between October of one year and April of the next, in 

 order to destroy the young borers before they enter the wood. 



Worthless, scrubby, borer-infested trees should be killed outright by 

 stripping the bark from 4 or 5 feet of the lower stem during August to 

 prevent sprouts and seed production from them, and at the same time 

 to destroy the eggs and young borers. Trees deadened in this manner 

 will usually be so completely killed that not a single root sprout will 

 appear. Therefore this method is of special value in preventing 

 sprout reproduction from inferior individual trees. 



SELECTING AND BREEDING BORER-RESISTANT TREES. 



The fact that some trees are more or less resistant to attack or injury 

 by the borer, while adjacent ones in the same grove are attacked year 

 after year and seriously damaged, suggests breeding races and varie- 

 ties of the species which would be permanently resistant. 



Breeding experiments have been begun in cooperation with the 

 Bureau of Plant Industry and the Forest Service, but it will require, 

 several years to get definite results. In the meantime, however, it is 

 important that seed and cuttings for commercial planting should be 

 selected, as far as possible, from trees which show least damage from 



