The hog louse, Haematopinus suis, is the largest louse found in the Northeast and is the only species of louse that attacks hogs. Adults are 1/4 inch long and are dull gray-brown in color with nearly black body margins. Hog lice spend their entire life on the animal and breed continuously year-round. A few days after mating, each female lays three to six eggs per day, for a total of about 90 eggs. The eggs are glued to the hairs close to the skin and hatch in about 2 to 3 weeks. The young begin feeding immediately and reach maturity in 10 to 12 days. Lice are most common during cold weather and are found mainly inside the ears and in the skin folds of the neck and legs. Any part of the body that offers protection may harbor hog lice.
Hog lice torment the animals by piercing their skin with needle-like mouthparts and sucking blood. The resultant itching and discomfort cause the animals to scratch with their feet and to rub against feeders, posts, or any stationary objects. This causes the skin to become thick, cracked, tender, and sore. Infested animals are restless, less profitable, and more susceptible to diseases that can cause death. Hog lice may also spread the swine pox virus to pigs. A heavy infestation causes a condition on the skin similar to measles. The hair cannot be removed without skinning, so hide loss and discounted carcasses can also result.
The following program will help prevent lice and mite infestations. Because new boars, sows, or feeder pigs added to your herd may carry mites, lice, or their eggs, you should treat all hogs that are added to your herd before they come in contact with your animals. A good time to stop lice and mange is when the sows are being readied for farrowing, even though mange or lice symptoms may not be evident. If the lice and mites are controlled on the sows, they will not have a chance to move to the young pigs. This is important, since a mange infestation on baby pigs spreads rapidly, and baby pigs should not be treated with most pesticides.
If an outbreak of lice or mange is detected in your herd, treat the entire herd, even though certain individuals may appear parasite-free. Pesticide sprays recommended for control of mange or hog lice are more effective when applied at the rate of 2 to 4 quarts of finished spray per animal using high-pressure sprayers. Spray small numbers of the animals at one time and give thorough coverage with special emphasis to the head, neck, and ears. A nonfoaming detergent (0.25 lb per 25-gal spray) may be added to the spray to help maintain coverage. If cold winter weather prevents the use of sprays for treating mange or louse-infested hogs, dusts and bedding treatments are available that give varying degrees of control.