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Cattle lice may be the most underestimated livestock insect in terms of economic losses. The USDA estimates that U.S. livestock producers lose $125 million a year to cattle lice. Heavy louse populations cause lowered milk production, loss of flesh, stunted growth, general unthriftiness and anemia. "Chronic" or "carrier" cows may abort due to louse-induced anemia. During severe winters, louse-infested animals are more susceptible to respiratory diseases. Fall and spring calves, yearlings, and older unthrifty cattle usually have the heaviest lice infestations. DESCRIPTIONAdult -- The cattle biting louse (1 to 1.5 mm) is yellowish-white with a reddish head and 8 dark crossbands on its abdomen. The shortnosed cattle louse (2.75 to 3.25 mm) has a short head that is nearly as broad as long and rounded in front. The head and thorax are yellowish-brown and the abdomen is blue. The longnosed cattle louse (2.5 mm) has a long "nose" and narrow body. The abdomen of the longnosed louse is bluish-black. The little blue louse (1.5 mm) is the smallest biting louse of cattle. The head is short and the sides of the abdomen have tubercles that project from the sides of each abdominal segment.Egg -- The small egg is delicate, white and barrel-shaped. The front end has a slight rim with a lid that is pushed off at hatching; the back end is glued to the hair. Nymph -- In general, the nymph is smaller than but similar in appearance to the adult.
BIOLOGYDistribution -- Cattle lice are found worldwide.Hosts -- Cattle lice usually attack only cattle. Damage -- Lice occur on cattle of all ages and breeds. They are most abundant on the top of the head and on the neck, shoulders, back, and rump. They crawl about freely, irritating the skin with both their sharp claws and their short, chewing or sucking mouthparts. Life History -- Eggs are attached to hairs close to the skin. They hatch in about 8 days and 3 nymphal instars develop over the next 18 to 21 days. Adult females, ready to lay eggs within a couple of days, outnumber males and live about 42 days. They lay about 30 eggs at the rate of about one egg every 36 hours. The life cycle (from egg to egg) is usually completed in 3 to 4 weeks. Cattle lice thrive at the normal surface temperature of the host's body. A variation of only a few degrees in either direction can be lethal. Infestations are usually light in summer and heavy in late winter and early spring. Account Login | Get Service | Contact Us | Site Map | Careers |
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Cattle Lice