University of Kentucky Entomology EntFacts
Information Sheets LICE ON BEEF AND DAIRY CATTLE by Lee Townsend, Extension Entomologist University of Kentucky College of Agriculture Lice are small, flat-bodied insects with legs modified for grasping hairs. They cannot survive off of the animal for more than a few days. Sucking lice, with their narrow, pointed heads, are blood feeders. Biting lice feed by scraping material from the skin and base of the hairs. The eggs, or nits, of both types are glued singly to hairs and hatch in about two weeks. The nymphs, or immature stages, resemble the adults but are smaller. They mature in about three weeks. Adults live two to three weeks and females lay about one egg per day. Infestations of biting and sucking lice have been associated with reduced weight gains and general unthriftiness of cattle. The economic impact of these small insects has been very difficult to assess. However, it appears that an average of 10 or more per square inch are necessary to have a significant effect. Lice are most abundant on animals during the period of greatest winter stress. Many veterinarians and producers believe that losses occur and some cattlemen will treat animals for lice just for the improved appearance that results. The potential for severe, direct losses caused by sucking or biting lice is low. Moderate to heavy infestations add to the impact of cold weather, shipping stress, inadequate nutrition, or harm from internal parasites or disease. The interaction between low levels of both lice and intestinal nematodes can reduce weight gains by more than 8%. The energy that lice "steal", coupled with other factors, can have a severe impact on animal health. Manifestations can be anemia, slow recovery from diseases, poor gains, or general unthriftiness. | |
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