4 BULLETIN" 1218, U. S. DEPARTMENT OF AGRICULTURE. 



In Louisiana and the southeastern part of Texas certain tabanids 

 are popularly called " charbon flies." Mitzmain (6) 2 very clearly 

 demonstrated in the Philippines that Tabanus striatus Fab. carried 

 the trypanosome causative of the disease surra, from an infected 

 animal to a healthy one. The same author ('/) in 1914 reported the 

 direct transmission of anthrax through the biting of T. striatus. 

 Morris (9), in 1918, transmitted anthrax through the bite of 

 Tabanus sp. 



Boerner and Hartman (1), in 1914, in dealing Avith methods of sup- 

 pression of anthrax in certain counties in Texas, were firmly con- 

 vinced that tabanids had much to do with the epizootic. The an- 

 thrax bacillus was found by them in cultures of bacteria taken from 

 the mouth parts, the feet, and from the ingested blood of these flies. 

 In addition to this evidence, it was found that from 90 to 95 per 

 cent of all the animals dying of anthrax in the five counties adjacent 

 to where the flies were captured had local swellings on parts of the 

 body most often attacked by this fly. Furthermore, unusual abund- 

 ance of the fly was coincident with widespread epidemics of the 

 disease. 



In the Antelope Valley of California, where anthrax has often 

 occurred, the same coincidence has been noted. It is a common opin- 

 ion in the -valley that the flies have much to do with transmission of 

 the disease. 



In 1906, the spread of surra among quarantined cattle imported 

 from India was attributed by Mohler and Thompson (8) to the 

 agency of Tabanus atratus Fab., some of which were feeding on 

 the animals. 



INFESTING MAN. 



In Utah, during recent years, there have been several cases among 

 human beings of what is known as the " deer-fly disease," commonly 

 called that because histories of the cases usually revealed a bite 

 from what is commonly known as the deer fly. That this fly, 

 Chrysops discalis, is the carrier of the disease to man has long been 

 suspected by physicians who have dealt with the malady. It re- 

 mained, however, for Francis and Mayne (2) of the United States 

 Public Health Service to demonstrate clearly the transmission of 

 the disease by this insect. 



ANTELOPE VALLEY. 



Antelope Valley, lying partly in Nevada and partly in California, 

 is about 23 miles long north and south (fig. 3). The valley is from 

 2 to 5 miles in width. It lies among the foothills of the east side 

 of the Sierra Nevadas, about 65 miles south of Reno. The altitude 

 at Topaz in the middle of the valley is about 5,400 feet. 



CLIMATE. 



The climate is typical of the semiarid valleys of the eastern slope 

 of the Sierras. There is not sufficient rainfall to grow crops with- 

 out irrigation. The growing season is comparatively short, being 



2 Numbers (italic) in parentheses refer to "Literature cited," p. 36. 



