410 ANNUAL EEPOETS OF DEPARTMENT OF AGRICULTURE. 



immediate publication and were submitted to the American Journal 

 of Hygiene. 



The larval investigations which have been carried on by the bureau 

 during the past three years, independently of the cooperative work, 

 have also been summarized and a complete report prepared. From 

 this, one article has been prepared in condensed form for publica- 

 tion, giving an account of the natural breeding places of Anopheles 

 in the locality of Mound, La. 



At the beginning of the present season, work was started on the 

 following three projects and is now being conducted along these 

 lines : 



Methods of larval control adapted to local conditions. 



Chemotropic responses and trapping of adult Anopheles. 



Continuation of the host-preference experiments. (In cooperation with the 

 department of immunology of the Johns Hopkins School of Hygiene and Public 

 Health.) 



INSECTS AFFECTING FOREST RESOURCES AND SHADE TREES. 



Dr. A. D. Hopkins has continued as leader of this branch of the 

 bureau work. 



INSECTS DAMAGING FOREST TREES. 



Studies of the principal forest insects of the United States, and 

 especially of the destructive pine bark-beetles, carried on for many 

 years, have resulted in the gaining of knowledge which is now being 

 put into effect in the most practical way in large-scale forest-insect 

 control carried on in cooperation with private owners and other 

 branches of the Government service. Some of the principal projects 

 are mentioned below. 



The southern Oregon-northern California control project. — 

 In my last annual report I stated that this control project is the 

 largest single one of the kind ever attempted. It is now in its second 

 season, and it is expected that the bulk of the work will be completed 

 by the close of the season of 1924. The cooperation has been admir- 

 able. The Forest Service of this department, the Indian SerAdce of 

 the Interior Department, and the private owners, represented by the 

 Klamath Forest Protective Association, have worked in the greatest 

 harmony, and the operations have been planned and supervised by the 

 Bureau of Entomology. The area over which this epidemic of pine 

 bark-beetles extends is a little larger than the State of Delaware, and 

 in the last 10 years in this region the western pine beetle has killed 

 over a billion board feet of merchantable yellow pine timber valued at 

 over $3,600,000. It may incidentally be mentioned that this is fifty 

 times as much as has been killed by fire on the same area during the 

 same period. It has already been shown that with the establishment 

 of as effective beetle control as has been established for forest-fire 

 control, losses due to the beetle can be reduced to a minimum. Since 

 the project was started last year, 260,343 acres have been gone over 

 at a total expense of about 36 cents per acre. It will take another year 

 to finish this work, and then, with some expenditure for maintenance, 

 it is very probable that nearly complete control of the possible insect 

 damage can be maintained. The private owners, the officials of the 

 Forest Service, and those of the Indian Service are gi-eatly pleased 



