Each tiny, oval egg is about 0.2 mm long. The white, circular larva has only three pairs of legs. Too small to be seen with the naked eye, this parasitic stage is about 0.2 mm in diameter. It is only slightly smaller than the adult. Itch mites can occur anywhere a host is present.
Infestations tend to be most common during cool weather months.
Mammals subject to infestation by races of this parasite include horses, cattle, hogs, dogs, rabbits, sheep, and man. Mites transferred from one type of animal to another cannot survive and soon die, although they may cause some annoyance before dying. They usually first establish themselves on the least hairy parts of their host's body. Once established, however, the mites may spread to all parts of the body. As a rule, itch mites spend their entire life cycle on the host.