By Mark Landefeld
Winter is the prime time for lice populations on beef cattle to increase. As temperatures cool and hair coats grow longer, producers need to be monitoring their livestock.
Constant rubbing is a sign or indicator your livestock may have biting and/or sucking lice. Both biting and sucking lice are spread by direct contact with other animals, and these parasites can cost producers a lot of money.
Some of this comes from production loss, but other losses occur when livestock rub equipment, fences and buildings causing damage to them.
A few cattle have lice year-round and are called carriers. This may only be 1-2% of the herd (usually older cows or bulls), but they can re-infect other animals causing increased populations among all the livestock.
Biting Lice
Biting lice survive by feeding on the skin, hair and sloughed skin cells of the animal. A complete life cycle of biting lice can occur in as little as three weeks, and adults can live as long as 10 weeks.
The adult biting louse has a brownish-amber-colored head with a darkly outlined abdomen that has a series of brown crossbars on a pale background. It is commonly found near the base of the tail and along the topline of the animals.
Sucking Lice
Sucking lice, on the other hand, are more serious pests that survive by penetrating the skin and feeding on the host’s blood.
Sucking lice are generally dark in color and typically found over the shoulders, down the animal’s neck, and on the ears, dewlap or brisket.
The short-nosed louse (Haematopinus eurysternus) can complete its life cycle in about 28 days, although the time period may range from 21 to 42 days.
Treatment
The non-systemic insecticides are effective against all types of lice, whereas the avermectins, moxidectin and eprinomectin (systemic products) mainly kill sucking lice.
Non-systemic insecticides can be used from around Nov. 1 through early January if cattle were not previously treated for internal parasites (grubs).
During this time there is a potential risk of choking, bloat or paralysis from a response to cattle grubs dying in critical tissues within the animal if systemic insecticides are used.
Non-systemic insecticides come as pour-on products, dust bags, sprays and products for cattle rubs (like the pyrethroids, cyfluthrin, lambda-cyhalothrin or permethrin). These can be used safely during the November to early January period.
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