In 3 to 20 days, these eggs hatch in tunnels, maturing to adults in 5 days. The female dies about 30 days after reaching maturity. Most often, an infestation begins on the inner side of the ear and spreads over the head, along the neck and across the body. The affected skin has small raised areas covered with brownish scabs. An intense itching may accompany the infes- tation, although in mild infestations itching may be negligible.
Mite activity increases as skin is warmed by fever or high environmental temperature.
This increases the irritation and feeding rates and may intensify the itching in affected pigs. Mites can be found on pigs year round, but during the winter when treatment is often difficult producers recognize a mange problem in their herds. Winter adds an additional stress to animals and, in many cases, pigs are in close contact, allowing the mites to spread throughout the herd. In summer, pigs are less likely to sleep close together, and mite transmission is slowed due to lack of pig to pig contact. Treatment is also easier in summer when concerns of animal stress due to spraying and handling are less.