362 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



the only way in which malaria is transmitted, and that the 

 low-lying lands or swamps have nothing whatever to do with 

 malaria except in so far as they furnish a breeding place for 

 mosquitoes. Much less, then, can the mists or bad air mal 

 aria in the Italian produce malaria. Without mosquitoes 

 there is no malaria. 



TEXAS FEVER OF CATTLE 



To the genus Babcsia (formerly known as Piroplasma) be- 

 long several species of blood parasites that are of great eco- 

 nomic importance. In the vertebrate host they live in the 



FIG. 154. Texas fever tick, Margaropus annulatus, young adult not 

 fully gorged. (About four times natural size.) 



red blood corpuscles, and they are transmitted from one 

 animal to another by means of ticks. The most important of 

 the diseases caused by the members of this genus is a disease 

 of cattle known in the United States as Texas fever, or tick 

 fever, or splenic fever. It occurs in nearly all tropical and 

 subtropical and in many temperate regions, and outside of 

 the United States is more commonly known as "red water." 

 In the United States it causes an annual loss estimated at $100,- 



