524 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



cate that the practice is useless and results only in the expendi- 

 ture of considei-ahle sums without returns. 



In addition to the work upon those two diseape-bearing species of 

 ticks, the study of a number of other injurious forms was continued 

 with especial reference to control. Among the more important ones 

 are the fowl tick, which practically prevents successful chicken rais- 

 ing in certain sections of the Southwest, and the si)inose ear tick, 

 which is an important pest to live stock in western Texas, New Mex- 

 ico, Arizona, and parts of California, Nevada, and Utah. The biol- 

 ogy' of about li) species of ticks, most of which are of economic im- 

 portance, has been worked out and the information put in form for 

 publication. 



SIMULIUM AND PELLAGRA. 



On account of the claim made by Dr. Sambon in the early part of 

 1910 that a species of fly of the genus Simulium transmits the dis- 

 ease of human beings known as pellagra in Italy, collections of flies 

 of this genus in various parts of the South were made. The work 

 down to the present time seems to show that there is no connection 

 whatever between the centers of pellagra infection and the localities 

 in which species of Simulium are to be found in the greatest numbers. 



WORK ON INSECTS INJURIOUS TO STORED PRODUCTS. 



In the course of the work on insects injurious to stored products, 

 which has been carried on, as previousl}^, under the direction of Dr. 

 F. H. Chittenden, especial attention has been given to fumigation 

 and other remedies, including the effect of hydrocyanic-acid gas and 

 bisulphid of carbon under different conditions, especially in hot 

 and cold weather. In Texas and at Washington, D. C, in cold 

 weather, it has been found that the gases are comparatively inoper- 

 tive in low temperatures. Bisulphid of carbon used during a high 

 temperature has been found unusually effective. The investigations 

 have been conducted chiefly in Texas, Kansas, and Oklahoma, and 

 considerable work of a preliminary nature has been done in the Dis- 

 trict of Columbia in special fumigators, and in cooperation with the 

 Bureau of Plant Industry at Baltimore, Md. The results of remedial 

 experiments with hydrocyanic-acid gas generated from sodium 

 cyanid and with bisulphid of carbon, liberated in a high temperature, 

 have been published. It has been shown that the lesser grain beetle 

 possesses less resistant power to most gases than most of the other 

 stored-product insects; that fumigations in low temperatures, espe- 

 cially below 50° F., are practically ineffective unless an excessively 

 large amount of bisulphid of carbon or of cyanid gas be used, and 

 that under these conditions it is very desirable that about 48 hours be 

 the length of exposure in order to insure killing all insects, even in 

 tight inclosures. It seems that under ordinary conditions and in a 

 temperature of between G5° and 75° F. a general standard of 2 pounds 

 to 1,000 cubic feet for 48 hours or more should be adopted for bisul- 

 phid of carbon treatments. 



One of the most troublesome insects investigated during the year 

 was the fig moth. Early in the fiscal year an agent was sent to 

 Smyrna to investigate the conditions under which figs coming to the 

 United States become vvorinj^, and on his return experiments were 



