BUEEAU OF ENTOMOLOGY. 225 



age percentage was not over 40, yet in every case where the control 

 work was done in accordance with the recommendations of this bureau 

 marked reduction in the death of the timber followed, ranging from 

 75 per cent to 95 per cent below that of the year preceding the begin- 

 ning of control work. 



The instruction and demonstration against the Dendroctonus 

 beetles in the national parks, inaugurated durmg the past year and 

 carried on by the Interior Department under the instruction of an 

 entomological ranger, was started in the Yosemite National Park and 

 has been carried on with the most gratifying results to the bureau 

 and the park officials. 



Miscellaneous. — Progress has been made in the work on the gen- 

 eral projects, especially on the relation of latitude, longitude, alti- 

 tude, and local conditions to msect life, which contmues to show the 

 great economic and broad application of a detailed knowledge of the 

 subject. The investigation of beneficial insects in their relation to 

 the natural control of destructive forest msects has yielded valuable 

 results in showing how, in connection with the practice of the per- 

 centage principle of control, they may be protected and encouraged 

 to render the best assistance to artificial control methods. A very 

 large amount of new data and material has been collected during 

 the year, represented by the records of observations on more than 

 30,000 specimens of reared msects, the collection of more than 20,000 

 specimens of insects and their work, and the identification of over 

 3,000 species, representing many thousands of specimens sent in by 

 correspondents. 



INVESTIGATIONS OF INSECTS INJURIOUS TO VEGETABLE AND TRUCK 



CROPS. 



Investigations of insects injurious to vegetable and truck crops 

 have been in charge, as heretofore, of Dr. F. H. Chittenden. The 

 more important subjects of research during the year have been insects 

 injurious to potato, sugar beet, and onion, the pea aphis, and msects 

 affecting cruciferous crops, such as cabbage, turnip, and the hke. 

 During the course of the year investigations for wliich stations were 

 established on Lon^ Island and ui Idaho have been completed, and 

 the stations accordingly are not now occupied. Work has been 

 temporarily discontinued ui Arizona, and new stations have been 

 opened in Michigan, Wisconsin, Louisiana, Mississippi, Kansas, and 

 southern CaUfornia. 



Enemies of potato and related plants. — The potato-tuber 

 moth, second only to the Colorado potato beetle as a pest, has been 

 given continuous study in California. Studies of its life history and of 

 its control by cultural methods have been completed, and the value of 

 cold storage ui checking the develoj)ment in stored tubers has been 

 demonstrated. In the field the species is beuig largely controlled by 

 natural enemies, which have also been carefufly studied. The 

 Colorado potato beetle is continually widenmg its range, although 

 slowly, southward and westward to the coast. In some sections it 

 destroys entire crops unless spraymg is practiced thorouglily. A 

 report on the potato flea-beetle is forthcoming. The insect enemies 

 of the tomato, as in past seasons, have been given a considerable 

 22814°— AGB 1915 15 



