INSECTS INJURIOUS TO DOMESTIC ANIMALS, ETC. 673 



the most serious of the ones attacking man is the tick which has 

 received the name of the Rocky Mountain Fever Tick (Derma- 

 centor venustus, Banks), because it has been shown to be an agent 

 in the transmission of the fever of that name, which is a highly 

 fatal disease occurring in many of the Rocky Mountain States but 

 most prevalent and virulent in the Bitter Root Valley of Montana. 

 This tick spends a part of its life on the smaller wild mammals and a 

 part on the large mammals, wild and domestic. Upon occasion it 



FIG. 592. The Rocky Mountain spotted fever tick. (After R. A. Cooley, 

 Montana Agr. Exp. Sta.) 



bites man, and in so doing may infect him with the fever if it has 

 previously received the virus from another infected person or 

 animal. 



The Cattle Tick* 



The most important of the cattle ticks, and one of the most 

 important of the arthropods affecting the cattle industry, is the 

 Texas Fever Tick or North American Fever Tick, a common 

 pest of cattle in the South and the sole means for the trans- 

 mission of the disease known as Texas Fever. This disease and 

 so the tick, has been the greatest obstacle to the establishment of 

 the livestock industry in regions of the South which are otherwise 

 well adapted to cattle raising. 



The fully grown adult ticks may be as much as a half inch long 

 and are thick bodied and oval in shape. The head is much smaller 

 than that of other ticks found on cattle and is reddish brown in 

 color. Body color is yellowish or a dull brown with mottling of 



* Margaropus annulatus. See Farmers' Bulletin 1057 and numerous other 

 U. S. Dept. of Agr. publications. 



