Lice • Lice populations build up on cattle in the winter months, and are mainly a problem from November through March. • Lice are not a problem on cattle in the summer months because they are not able to tolerate warmer temperatures in populations high enough to cause noticeable symptoms. • Cattle with lice infestations will scratch off their hair in affected areas and lick these areas because of irritation. • Cattle can be examined for the presence of lice in a squeeze chute by parting the hair on the face, brisket, shoulders, hips and tail head.
Lice • Cattle spread lice from one another by close contact and grooming. • If control is implemented, all the animals in the herd must be treated. • Ringworm and scabies may also present symptoms similar to lice infestations, so cattlemen should check carefully before treating. If in doubt, consult your veterinarian. • Lice have gradual metamorphosis, which consists of eggs, nymphs and adults. • Lice must spend their entire life cycle on the host animal, meaning the eggs, 3 nymphal instars, and adults are all present on the animal at the same time. • Lice can go from the egg stage to the adult stage in as little as 16 days, depending on the species.
Biting Lice • The cattle biting louse does not actually bite the animal. Biting lice feed on organic matter on the surface of the skin. • Just the presence of the louse causes general irritation which causes the animal to scratch and rub.
Sucking Lice • There are three main species of sucking lice. • These three species are the short nosed cattle louse, the long nosed cattle louse and the little blue louse. • All sucking lice have piercing sucking mouthparts and pierce the skin and take blood from the animal. • All three nymphalstages as well as the males and females suck blood. • Cattle appear greasy when infested with sucking lice
Detecting lice infestations • Lice should be suspected when cattle show signs of rubbing. • Rubbing causes hair loss on the neck, shoulders and rump and needs to be differentiated from the normal appearance of the seasonal shedding of the winter coat. • To detect lice, run cattle through a chute and examine the skin by parting the hair. Good lighting and a magnifying glass will help you see the lice as they attempt to move away from direct sunlight. • Biting lice of cattle are recognized by a rounded head, light brown color and high mobility as they move when the hair is parted. Sucking lice are grey or blue grey and have a pointed head that tends to remain fixed to the skin. You may also see eggs, which are white and cemented to the shafts of coat hairs in clumps.
Lice Control • A second treatment for lice control must be made 2 to 3 weeks after the initial treatment because the developing eggs present at the time of initial treatment will hatch and the residual pesticide will likely not be of a concentration high enough to kill the newly emerging nymphs.
Sucking Cattle Lice (NC State W. Watson) Severe lice infested animal. (Angus Beef Bulletin; L. Townsend Univ. of Kentucky)