U.S.D.A.,B.E.Bul.58.Partn. F.I. I., August 18, 1906. 



SOME INSECTS INJURIOUS TO FORESTS. 



THE WESTERN PINE-DESTROYING BARKBEETLE. 



(.Dendroctonus irevicomis Lec.)o 



By J. L. Webb, 

 Special Field Agent, Forest Insect Investigations. 



INTRODUCTION. 



The object of this paper is to give available information on this 

 insect and methods of combating it, with special reference to the 

 results of investigations by the writer during the summer of 1905 in 

 central Idaho. 



The need of the investigations was suggested in a letter dated 

 August 10, 1904, from Mr. Gifford Pinchot, forester of the U. S. 

 Department of Agriculture, to Dr. L. O. Howard, chief of the Bureau 

 of Entomology, as follows: 



I learn from the Payette Lumber and Manufacturing Company, one of the Weyerhaeusers, 

 whose land lies onithe Payette River north of Boise, that the pine in their holdings is said to 

 be dying from the attacks of insects. If it were possible for you to assign Doctor Hopkins, 

 or one of his assistants, to make examination of this region, unless it has already been done, 

 I should greatly appreciate it, and I should likewise appreciate your sending to Mr. Edgar M. 

 Hoover, general manager of that company at Boise, any information you may have bearing 

 on this subject. 



In response to this request the matter was referred by Doctor 

 Howard to Dr. A. D. Hopkins, in charge of forest insect investigations, 

 for attention, and Mr. H. E. Burke, an assistant, was instructed to 

 make preliminary investigations in October of the same year. In May, 

 1905, the writer was assigned to this work, with instructions from Doc- 

 tor Hopkins to make a detailed study of the forest insects of the region, 

 with special reference to determining the following points: (1) The 

 . relation of the several species of insects to the dying of the trees; (2) 

 the number of species involved, the relation of each to primary and 

 secondary attack, and the life histories of the primary and secondary 

 enemies; (3) the extent of the infested area, the percentage of timber 

 killed each year during the past two or three years within given areas, 

 the approximate losses, etc. ; (4) the relation of logging operations to 



a Order"Coleoptera, family Scoljrtidse. 



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