The astigmatid mites, as suggested by the name, are characterized by a lack of stigmata. These mites tend to be small and to have lightly sclerotized bodies. The third and fourth pairs of legs tend to exit the body some distance behind the first and second pairs of legs. The end of each leg is a tarsal segment that bears the sucker-like feet which support the mite. Some Astigmata are free-living mites that feed on organic matter. Other astigmatid mites are external feather mites of birds, live in the quills of feathers, or burrow into the skin of birds; two families are actually internal parasites of birds. The astigmatid mites contain several important parasites of large animals, e.g., Psoroptesovis, Chorioptesbovis, and Sarcoptesscabiei.
There are four astigmatid mites that are of importance in feline parasitology: Otodectescynotis, the ear mite of dogs and cats; Notoedrescati, the mange mite of cats and rabbits; Sarcoptesscabiei, the mange mite of dogs, humans, and other hosts; and Lynxacarusradovskyi, the hair-clasping mite of tropical cats. These mites tned to be slow-moving and weakly sclerotized. Respiration is integumental, i.e., there are no stigmata. The largest of these mites is Otodectes, the smallest is Notoedres. Otodectes, Sarcoptes, and Notoedres are similar to each other in appearance. These are rather dorsally compressed and round mites that have short legs which terminate in sucker-like feet typical of the astimatid mites. Although the legs of Lynxacarus also terminate in sucker-like feet, the general appearance of this mite is much different than that of the other three found on cats. The body of Lynxacarus is elongate and appears laterally compressed. Otodectescynotis is usually found in the ear canal where the mites wander around on the surface of the skin, Notoedrescati is found in burrows in the skin (usally on the ears and face), and Lynxacarusradovskyi is found clinging to the hairs of the cat (often around the anus and on the tail); Sarcoptesscabiei is only rarely found on cats.