. The Acarina or mites. A review of the group for the use of economic entomologists. Mites. THE ACAEINA OE MITES. 67. Fig. 125.—Tarsus IV of Ambhjomma. (Original.) at articulations. The cause of Texas fever is a minute protozoan parasite, Babesia bigemina. This is taken up with the blood of Margaropus, which then inoculates each animal that it attacks. And even the young that have not infested any animal may produce the disease. The young ticks (fig. Ill), called "seed ticks," are born on the ground; they climb upon grasses or bushes and await the coming of cattle. Each attaches itse
. The Acarina or mites. A review of the group for the use of economic entomologists. Mites. THE ACAEINA OE MITES. 67. Fig. 125.—Tarsus IV of Ambhjomma. (Original.) at articulations. The cause of Texas fever is a minute protozoan parasite, Babesia bigemina. This is taken up with the blood of Margaropus, which then inoculates each animal that it attacks. And even the young that have not infested any animal may produce the disease. The young ticks (fig. Ill), called "seed ticks," are born on the ground; they climb upon grasses or bushes and await the coming of cattle. Each attaches itself at the first opportunity and begins to draw blood. In about a week it molts, remaining on the host during this period. The male increases but little in size, but the female becomes enormously swollen and in about a month she is ready to drop off and deposit eggs (fig. 113). Young or "seed ticks" of the cattle tick may live several months with- out food, and even remain alive when submerged in water for 3 months. The adults can Hve for long periods without food, but probably not as long as the argasids. Once in the blood of cattle the parasite destroys the red blood corpuscles and causes a thinness of blood, the haemaglobin of which appears in the urine. After death the spleen and liver are found to be greatly enlarged. The most promising preventive seems to be the removal of cattle from pasture for one year. This pasture disinfection may be hastened by cultiva- tion for one year, or grazing it to sheep. It has been noticed that southern cattle may become immune, and with this hint a method of vaccination was devised for treating northern cattle when taken south. A variety of the cattle tick (M. annulatus var. australis Ful- ler) has a posterior median projection to the body; it occurs in tropical regions, and also transmits Texas fever. The typical species (Margaropus uinthemi Karsch) and an Afri- can species have the hind pair of legs enormously enlarged in the
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