2 DISTRIBUTION OF THE SPOTTED-FEVER TICK. 



Mr. W. V. King was employed as an agent of this bureau for the 

 purpose of collecting specimens especially outside of Montana. In 

 this investigation he worked under the general direction of Mr. 

 W. D. Hunter, but under the immediate supervision of Prof. R. A. 

 Cooley. At the same time Mr. J. D. Mitchell, Mr. F. C. Pratt, and 

 the writer, as agents of the Bureau of Entomology, made collections 

 in the southern and central portions of the Rocky Mountain region. 

 In 1910 Mr. W. D. Hunter formulated plans for obtaining further 

 information regarding the distribution of the species. By the use of 

 circular and personal letters, the aid of several hundred individuals 

 throughout the Western States was obtained. Through the coopera- 

 tion of these correspondents a large number of ticks was procured. 

 All of the material was sent to the laboratory at Dallas, Tex., where 

 the immature ticks were reared to adults and all specimens were 

 carefully detemiined. Mr. Nathan Banks, a specialist in this group 

 of animals, identified much of the material received during 1909. 



AVHERE THE TICK OCCURS. 



As a result of this investigation the distribution of the spotted-fever 

 tick, as shown by the accompanying map (fig. 1), was determined. 

 The map includes a number of localities in Montana where, in 1909, 

 Prof. R. A. CoolcA' determined the species to occur. Our knowledge 

 of the distribution is based upon 1,300 lots of ticks, 815 of which were 

 DerTnacentor venustus. The specimens of this species were obtained 

 from 225 diflferent localities. The numbers of localities in the dif- 

 ferent States in which this tick was collected are as follows: Cali- 

 fornia 3, Colorado 15, Idaho 42, Montana 72, Nevada 11, New Mexico 

 2, Oregon 15, Utah 12, Washington 27, Wyoming 26. The shaded 

 portion of the map includes all of the localities where the tick has 

 been found. The darker shading indicates the regions where the 

 species occurs in greatest abundance. There is no doubt that there 

 are areas of considerable extent, within the territory indicated as 

 being infested by the Rocky Mountain spotted-fever tick, where the 

 tick is entirely absent or where it is found only occasionally. 



The northern part of the Rock}^ Mountain region in the United 

 States is the territory principally infested, but the river valleys and 

 sagebrush plains to the west are more or less heavily infested. Al- 

 though the spotted- fever tick occurs in the eastern edge of the Cas- 

 cade Mountains, it does not appear to exist in the main Cascade range 

 and has never been found to the west of the divide formed by those 

 mountains. It has been found in the western portion of the Black 

 Hills of South Dakota, and probably occurs throughout those hills. 

 There is no doubt that the species is common in southern British 

 Columbia and possibly eastern Alberta. Two females were collected 

 by Dr. H. G. Dyar at Kaslo, British Columbia. This locality is about 



