U. S. D. A., B. E. Bui. 83, Part I. F. I. I., October 11, 1909. 



PRACTICAL INFORMATION ON THE SCOLYTID BEETLES 

 OF NORTH AMERICAN FORESTS. 



I. BARKBEETLES OF THE GENUS DENDROCTONUS. 



By A. D. Hopkins, 

 In Charge of Forest Insect Investigations. 



INTRODUCTORY. 



The first part of this bulletin supplements Technical Series No. 17, 

 Part I, of this Bureau, in giving facts of practical interest and 

 importance on a group of barkbeetles which contains the most 

 destructive enemies of the principal coniferous forest trees of North 

 America. 



To avoid the too frequent repetition of technical and common names 

 in the text or in footnotes, the species number is used, referring to 

 the corresponding number in a classified list of technical and com- 

 mon names in Plate I. 



The list of publications, in which references are to be found to 

 some economic feature of one or more species, is arranged in chrono- 

 logic instead of alphabetic order, so that the reference in the text 

 is to the year in which the particular article referred to was pub- 

 lished, as well as to the author's name. A more extensive bibliog- 

 raphy is found in Technical Series No. 17, Part I. 



HISTORICAL. 



The name "Dendroctonus," which means Tcillers of trees, was pro- 

 posed in 1836 by Dr. W. F. Erichson to designate a genus of beetles 

 which was then represented by two described species— the European 

 spruce beetle (No. 21) (see Plate I) and the black turpentine beetle 

 (No. 22). Between that time and 1897 ten more North American 

 species, as at present recognized, were added, one (No. 18) by 

 Kirby in 1837, one (No. 17) by Mannerheim, 1843, one (No. 23) by 

 Le Conte, 1860, one (No. 4) by Zimmerman in 1868, two (Nos. 12 and 

 20) by Le Conte in 1868, one (No. 7) by Chapuis in 1869, one (No. 1) 

 by Le Conte in 1876, one (No. 8) by Dietz, 1890, and one (No. 24) 

 by Blandford in 1897. The writer has added twelve (Nos. 2, 3, 5, 6, 



