Fig. 20—Itch-mite (Sarcoptes scabiei). (After Murray.)
Fig. 21—Harvest-mites or "jiggers." (Leptus irritaus and L. americanus.) (After Riley.)
The minute whitish mites ([Fig. 20]) that cause this disgusting disease are barely visible to the naked eye. They are usually very sluggish but become more active when warmed. They live in burrows just beneath the outer layer of skin, sometimes extending deeper and causing most intense itching. As the female burrows, she lays her eggs from which come the young mites that are to spread the infection. Various sulphur ointments and washes are used as remedies. Cleanliness will prevent infection.
Closely related to the itch-mite of man (Sarcoptes scabiei) are several kinds attacking domestic animals, causing mange, scab, etc. The variety infesting horses burrows in the skin and produces sores and scabs, and is a source of very great annoyance. These mites may also migrate to man. Tobacco water and sulphur ointments are used as remedies.
Horses and cattle are also infested by other mites (Psoroptes communis) which cause the common mange. These do not burrow into the skin but live outside in colonies, feeding on the skin and causing crusts or scabs. The inflammation causes the animal to scratch and rub constantly and often causes the loss of much of the hair.