TICK, an arachnid (Boophilus annulatus) re lated to the mites, and prevalent in the western and southwestern States. It is a reddish, coriaceous, flattened or swollen creature from a quarter to half an inch in length. The cattle tick lays a great many eggs, nearly oval, dark brown, coated with a hard secretion, the process of egg-laying lasting for several days or week. The young tick, on hatching, is whitish, afterward turning brown; it has three pairs of legs. After molting it becomes a nymph, when the fourth pair of legs is added. During the nymph stage the reproductive organs develop. After another molt it becomes sexually mature. It completes its development from the larva to the adult on cattle. After this second molt the couple pair, and the male grows but little. The female, voraciously feeding on the blood of her host, grows to a gigantic size, her body swelling and becoming gorged with blood and eggs. The males can be easily detected by their smaller size, and by the extension of the shield over the entire back. Ticks live upon the blood of their host. The females, as they increase in size, store away quantities of the ingested food in an immense convoluted chamber or ap pendage of the stomach. In summer only three or four days after the final molt are necessary for the ticks to become large. When fully gorged, and the eggs fertilized, the female loosens her hold in the skin of her host, and falls to the ground, where she lays her eggs, after which her body contracts, shrivels up and then dies. The young ticks get access to cattle by climbing bushes, whence they reach out and attach themselves to passing animals.
It has been proved that ticks, by sucking the blood of cattle infested with the Texas fever •germ, which is a sporozoon (Apiosoma bigeminion), may communicate the disease (bo vine malaria) to healthy cattle, just as the sporozoon' blood-parasite of yellow fever, or of malaria, is communicated by a mosquito (Ano pheles). In dealing with ticks it should be
remembered that it breathes by spiracles, or minute holes in the sides of the body. By the use of oil, or any greasy substance, those open ings may be covered, thus asphyxiating the creature. The ticks may thus be killed by dipping or spraying the cattle with cotton-seed oil. Cattle should be kept away from wooded or bushy pastures. Rotation of pasture is also used by stock farmers, so that the tick may die of starvation. The United States Department of Agriculture has conducted the work of eradicating the cattle tick from the southern States in co-operation with the States affected. A total area of 275,782 square miles had been made free of this pest up to 1 July 1915.
There are one or two forms very closely allied to the Texas cattle-tick, and named Boo philus australis; they are regarded by experts as either distinct varieties or species from B. annulate:. They transmit the cattle-fever in the countries above named. Another sub species or variety, the blue tick (B. decoloratus) in South Africa transmits the same disease in that region. .
The Lone Star tick (Amblyomma xnipuncta) is, next to the cattle-tick, to be held responsible for the transmission of the Texas fever. It may be recognized by the simple bright silver spot on the back.
Bibliography.— Curtice, 'The ((Journal of Comparative Medicine and Veteri nary Archives' 1891-92) ; Salmon and Stiles, 'Cattle-Ticks of the United States' ((17th An nual Report of the Bureau of Animal Indus try,) Washington 1902) ; Law, James, 'Text Book of Veterinary Medicine' (Ithaca 1911) Hutyra and Marek, 'Special Pathology and Therapeutics of the Diseases of Domestic Ani mals' (Amer. ed., by Mohler and Eichhorn, Chicago 1912); and 'Special Report on Dis eases of Cattle' of the United States Bureau of Animal Industry (rev. ed., Washington 1912).