Body flat and broad; skin leathery and tough. Fore legs curved, adapted for climbing among the hairs. Some (_e.g._ the Forest Fly) have a pair of wings, others (the Sheep Louse Fly) are wingless. They bring forth living maggots, each time one only, which is ready to become a pupa immediately. They reproduce several times. Here belong: 1. The =Forest Fly=, =Spider Fly=, or =Flat Fly= (_Hippobosca equina_), about one-third of an inch long, brown, with broad abdomen, and two broad stumpy wings. Occurs in summer and early autumn, chiefly on horses, especially near the anus, on the belly, and on the flanks. It sucks blood, and irritates by running about on the body. Seldom flies. 2. The =Sheep Louse Fly=, wrongly called “sheep louse” and “sheep tick” (_Melophagus ovinus_); about one-fifth of an inch long, wingless, rusty yellow, with brown abdomen, very hairy. Climb slowly about among the wool of the sheep, and suck blood. Their excrement may colour the wool green. Lambs especially are much hindered in their growth by this fly. The fleece is also damaged, for the itching set up by the insect forces the animal to rub itself against things so that the wool gets pulled out. The flies are chiefly found on meadow sheep; but relatively few in winter. The parasites leave the body of their host for the purpose of reproduction, and lay their maggots, which at the time of birth are nearly one-sixth of an inch long, under little bits of earth or heaps of dung. When sheep are kept in folds no permanent result can consequently be expected from the use of any remedy if, at the same time, the fold and all its contents are not kept clean. The walls must be cleansed, and washed with caustic potash, to which carbolic acid has been added. _Curative Washes_: A decoction of walnut leaves and vinegar. Turpentine, soapsuds, decoction of tobacco. Washes containing arsenious acid (_e.g._ Bigg’s Improved Sheep and Lamb Dipping Composition) must be used with caution; unpalatable substances may be added, so that the sheep will not lick them, or else a muzzle may be employed. NINTH ORDER: =Aphaniptera= (FLEAS). Body strongly compressed laterally. Head small. Mouth-parts adapted for sucking and biting. Legs long, especially the last pair. They possess the power of springing. Wingless. Complete metamorphosis. Larva worm-like, legless, hard-headed. The =Dog Flea= (_Pulex serraticeps_), which only occasionally passes on to human beings, lives on dogs and cats. _Remedy_: Sprinkling the moistened hair with Persian insect powder or powdered parsley seed. TENTH ORDER: =Parasita= (LICE).