LETTER OF TRANSMITTAL. 



L". S. Department of Agricultuee, 



Bureau of Entomology, 



Washington, B. C, March 16, 1909. 



Sir: I have the honor to transmit herewith manuscript of the 

 first part of a bulletin of the technical series to be entitled "Contri- 

 butions toward a Monograph of the Scolytid Beetles." This family 

 of beetles includes some of the most important enemies of North 

 American forests, as well as of crude forest products, and therefore 

 must demand special attention in future systematic and economic in- 

 vestigations by this bureau and by forest entomologists connected 

 with other public institutions and private enterprises. It is necessary 

 as a foundation for such work, that the heretofore described species 

 should be accurately identified, that those new to science should be 

 described, and that this information, together with other systematic 

 data based on origmal research by this bureau, should be made availa- 

 ble in the form of contributions to a monograph. This work has 

 been undertaken by Dr. Hopkins, of this bureau, and the greater 

 part of the collecting and working up of the material has been com- 

 pleted. Delay in publication will be avoided, and it is believed that 

 the published results will be more useful in future- S3^stematic and 

 economic investigation if the results relating to groups of species 

 which have similar characters and characteristics and similar rela- 

 tions to given economic problems are published as parts of a bulletin 

 rather than in one undivided publication. These technical parts 

 are to be supplemented in a like manner by parts of a bulletin of the 

 regular series, giving information of immediate practical importance 

 to the forester and owners and managers of private forests. 



The first part of this bulletin is entitled "The Genus Dendrocto- 

 nus. " It embodies the results of extensive systematic investiga- 

 tions of the genus, carried on b}- Dr. Hopkins during the past 17 

 years, and is of especial interest and importance from the fact that 

 it deals with a small group of beetles which are the most destructive 

 enemies of the principal coniferous forest trees of North America. 



The discussions and illustrations relating to anatomical and tech- 

 nical details are necessary as a basis for the correct description, inter- 

 pretation, and recognition of generic and specific characte.-s, on which 

 depends the future success of economic work on the scolytid beetles, 



