226 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



the loss has reached 80 per cent. The bureau has shown that a great 

 proportion of this loss can be avoided by preventing alfalfa along 

 fence lines and on check ridges, roadsides, and ditch banks from 

 going to seed before the maturing of the regular seed crop. It is 

 shown that the practice of producing late seed crops and pasturing 

 off severely infested fields deserves strong condemnation and should 

 cease. 



Other investigations. — Other investigations in this section have 

 been concerned with the range caterpillar in New Mexico, joint- 

 worms, the clover-seed midge, and the clover-root borer in Oregon, 

 and many other species of somewhat less importance. 



INVESTIGATIONS OF INSECTS AFFECTING FOREST AND SHADE 



TREES AND HARDY PLANTS. 



Investigations of insects affecting forest growth, forest products, 

 shade trees, and hardy shrubs have been continued, as heretofore, 

 under the direction of the Forest Entomologist of the bureau, Dr. 

 A. D. Hopkins. 



The western pine beetle. — The most destructive enemy of the 

 yellow pine of the Pacific slope forests is the western pine beetle. 

 An exceptional opportunity has developed during the past two years 

 in the vicinity of the Pacific slope field station at Ashland, Oreg., 

 for an extensive study of this insect. An area of over 2,000 square 

 miles in southern Oregon and northern California is affected. The 

 principal centers of the infestation are on the watersheds of the 

 Klamath, Rogue, and Applegate Rivers. Careful estimates show 

 that over 10,000 trees, representing 8,000,000 board feet, were killed 

 here by this beetle in 1915. Two thousand three hundred of the in- 

 fested trees have been marked for continuous observations on the 

 development of the broods of the beetles that overwintered in the 

 bark. The area is also divided into units for special cruising experi- 

 ments and reconnaissance studies and for the purpose of studying 

 the infestation under the varying local conditions. Special cages to 

 include sections of the trunks of large trees, as well as other types 

 of cages and rearing houses, have been devised and constructed to 

 facilitate the attainment of some of the specific objects of the in- 

 vestigations. While it will require several years to complete these 

 studies, the results attained during the year are worthy of note, 

 especially the development of economic methods of conducting recon- 

 naissances and cruises of infested areas and estimating the character 

 and extent of an infestation; in addition, improved methods of pro- 

 cedure in control of the beetle have been worked out. 



Demonstration control work on the western pine beetle was car- 

 ried on under the supervision of a representative of the bureau on 

 privately owned timberlands on the McCloud River of California. 

 This was completed in June, 1915, and has proved a complete success. 

 The project involved 46,470 acres, on which 1,962 infested trees were 

 treated. 



Inspection of old control areas. — In the fall of 1915 areas in 

 the San Isabel, San Animas, Pike, and White River National Forests 

 and on three extensive private holdings in Colorado where control 



