BUREAU OF ENTOMOLOGY. 243 



SOUTHERN FIELD-CROP INSECT INVESTIGATIONS. 



Dr. W. D. Hunter has been in charge of these investigations, as 

 formerly. 



Cotton -BOLL weevil killed by poison. — One of the most striking 

 achievements of the bureau cuhninated during the year in the an- 

 nouncement of the vahie of powdered lead arsenate or calcium 

 arsenate against the cotton-boll weevil. After years of experi- 

 mentation the bureau is now able to announce that the weevil can 

 be killed during the summer months by dusting the cotton with 

 either of these poisons at the rate of 5 pounds per acre, with three 

 to five applications at weekly intervals. The poisoning, to be most 

 effective, should be done between 4 p. m. and 9 a. m., and the powder 

 should be applied by means of a rotary dust gun or by power 

 machinery. A special power machine has been developed which will 

 cover nearly 200 acres per day. The cost of treatment is about $1 

 per acre for one application. Distinct gains in yield of from 250 

 to 1,000 pounds of seed cotton have been obtained. It is hoped that 

 the application of this discovery will greatly increase the yield per 

 acre of cotton, one of the most important crops of the Nation. 



Other cotton insects. — Other work on cotton insects, as indicated 

 in the last annual report, has been carried on at Tallulah, La., Madi- 

 son, Fla., and El Centro, Cal., the recent developments of cotton in 

 the last locality, in the Imperial Valley, necessitating careful watch 

 for cotton pests. 



Eesearch work on the pink boUworm of cotton in the Laguna 

 district of Mexico has been carried on by experts of the bureau de- 

 tailed to the Federal Horticultural Board, and will be mentioned 

 in the report of the board. 



Other southern field-crop insects. — On account of the extension 

 of sugar-cane culture in southwestern Texas, a laboratory has been 

 opened at Brownsville for the investigation of sugar-cane insects. 



The investigations on tobacco insects, mentioned in the last report, 

 have been continued. 



The demands of the War Department for great quantities of castor 

 oil led to very extensive planting of castor beans under contract in 

 various southern States. Early in the season complaints began to 

 come in of insect injury to these plantations, and the bureau has 

 given especial attention to the control of these pests. 



INSECTS AFFECTING THE HEALTH OF MAN AND ANIMALS. 



With the beginning of the war, very elaborate tabulations and 

 card indexes of the relationships of insects to the health of man and 

 animals were prepared. This information has been placed at the 

 service of the War Department and has enabled the bureau to give 

 prompt service in many emergency cases. A close contact has been 

 maintained with the sanitary officers, so that the bureau has been able 

 to render service in the solution of certain camp jjroblems. 



Acting in cooperation with the National Research Council and the 

 War DeiDartmentj a study of the body louse was taken up and in- 



