The adult hog louse is about ¼ inch long and slate blue in color. Thus difficult to see on dark-colored animals although it is the largest of the animal species of lice. Lice feed on the tender areas of skin and are first noticed inside the ear or in folds of skin around the neck of the pig. They feed frequently for an average of ten minutes at a time. Eggs are deposited firmly on a hair shaft close to the skin. Eggs hatch within 2-3 weeks. Nymphs feed for two weeks or longer and molt three times. Adult lice live for about 5 weeks, and they may have as many as twelve generations per year.
Heavy louse infestations cause a skin condition similar to measles. Lice feeding results in much irritation and discomfort to swine. Infested hogs scratch vigorously and rub against feeders, posts or other objects, which results in extensive hair loss and skin wounds. The skin becomes cracked, tender and sore. Infested hogs are restless, less profitable due to reduced performance and more susceptible to disease. Little has been actually reported related to economic losses from lice. Some reports indicate reductions in weight gain and feed efficiency as a result of lice or mange mites. Other studies showed no impact of lice on swine weight gain or feed efficiency.
Louse infestations are usually less severe and spread less rapidly in
well-fed swine herds, where good management and herd health practices are
maintained. SPF breeding stock and
quarantine of any new animals brought to the unit for a period of time all help
reduce transmission of parasites within the herd.
Insecticides for use on swine lice and mange mites are listed in table form
at the end of the chapter.
Categories: Livestock insects, Swine, Hog Louse
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