ANIMAL PABASITES AND PARASITIC DISEASES 333 



and examined under a microscope. By placing the scabs on a 

 warm, black background a strong hand lens is sufficient to dem- 

 onstrate their presence, but not their genera. 



The only certain way to destroy mange mites is to apply a 

 substance over the entire surface of the body that will poison 

 the parasites. Sulphur dioxid gas is a most effective remedy 

 but requires a special apparatus for application. A mixture of 

 flowers of sulphur, bicarbonate of potash, and a bland oil in 

 equal parts has given fairly good results. Before applying 

 this mixture, the animal should be clipped. This dressing should 

 be left on for a week and gently rubbed in daily. The harness, 

 currycombs, brushes, and other stable paraphernalia should be 

 t-horoughly saturated with a 20 per cent, coal tar dip solution to 

 kill any mites which may have crawled onto them. 



The scab mite of cattle is closely related to and resembles the 

 mange mite of the horse. There are several genera, the common- 

 est being the Psoroptes communis. These parasites live in 

 colonies on the surface of the skin. Unless steps are taken 

 to control them, serious losses result. The back, loins, and croup 

 are first attacked because the animals cannot scratch these parts. 

 Scabs form from the serum which oozes through the prick in the 

 skin made by the mite to obtain food. The scabs pile up and the 

 hair gets rough and finally drops out. The animal rubs against 

 sharp objects to relieve the intense irritation. 



Treatment consists in dipping and applying remedies that will 

 kill the parasites without injuring the cattle. A lime-sulphur dip 

 has been found by the United States Bureau of Animal Industry 

 to be the most successful means of eradicating this disease. Full 

 directions for applying the treatment are given in Farmers' 

 Bulletin 1017. 



The scab mite of sheep is the most destructive external para- 

 site infesting sheep. Its attack is insidious, course rapid, and 

 effects very injurious. This mite is known technically as 

 Psoroptes communis. 



The first indication of this disease is the tendency of infested 

 sheep to nip at the sides where the parasites are causing irrita- 

 tion. This leaves the wool moistened with saliva, so that the 

 dust will settle on the affected parts when the animals are driven 

 along dry roads. The fleece, in case scab mites are present, 

 appears taggy, rough, and felted. By separating the wool and 



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