By Kristen Tribe

Cattle Biting Louse

Physical characteristics:
The head is reddish-brown, broad, blunt and flat. The abdomen is yellowish-white with dark transverse bands. 1/15 to 1/25 of an inch long.

Location on host:
They group at the base of the tail, on the shoulders and along the back of livestock. They then spread down the sides and along the neck and may be found anywhere on the host's body. During the summer, they persist mainly on the tail, head and perhaps in the ears.

Life history:
The female begins depositing eggs about three days after attaining maturity. One egg is deposited every 36 hours for the first 15 days but the rate decreases after this time. Egg-to-adult development averages about 1 month but varies with skin temperature of the host as well as moisture conditions. Females may live as long as six weeks, depositing only 20 to 30 eggs each.

Short-Nosed Cattle Louse

Physical characteristics:
The head and thorax are yellowish-brown, and the abdomen is slate blue. It's distinguished from the long-nosed cattle louse by its comparatively short head and cone-shaped plates on the lateral margins of the abdomen. The head is about half as wide as the body, short and nearly as broad as long and bluntly rounded in front. Females are about 1/8 of an inch long, and males are slightly smaller.

Location on host:
In the winter, they're found on top of the neck, but secondary breeding sites are the sides of the neck, dewlap, back, base of the horns and base of the tail. During summer, some can be found on the inside of the ear near the tip.

Life history:
Females deposit one to four eggs per day for 15 days or longer. Average life cycle is 20 to 41 days.

Long-Nosed Cattle Louse

Physical characteristics:
Abdomen is bluish-black. A longer "nose" or narrow body gives it a slender appearance.

Location on host:
Most common sites of infestation are the dewlap and shoulders. As spring approaches, remaining lice migrate to the shoulder area.

Life history:
Females deposit about one egg a day. The egg-to-egg life cycle is about 23 to 30 days.

Cattle Tail Louse

Physical characteristics:
The head, thorax and abdomen are dark brown. 4.5 mm long.

Location on host:
Eggs are deposited almost exclusively in the switch of an animal's tail. After hatching, they move up the tail to soft-skinned areas including the tail, head and neck. Calves often become heavily infested about the face from nursing the dam through the rear legs.

Life history:
Life cycle is unknown but eggs take about 11 days to hatch.

"Little Blue" Louse

Physical characteristics:
Head is short and broadly rounded. It's the smallest of the sucking lice.

Location on host:
They tend to cluster on the front part of the animal, and infestations have been noted along the top line and under the tail.

Life history:
Little is known about the life history except that eggs hatch in about 13 days.

If the mention of LICE makes your SKIN CRAWL, imagine how cattle suffer with an actual infestation. Lice live their whole lives on the host animal, making meals from dead skin, hair and even blood in some cases. The slightest movements of these pests, in addition to their bites, cause severe itching that even the most violent scratching against a fence post can't cure.

Cattle in Texas and Oklahoma can be attacked by biting lice or sucking lice, but Dr. Clifford Hoelscher, Extension entomologist, says biting lice are usually the source of most problems in Texas. The biting lice eat bits of flaked skin, hair and other organic materials, while sucking lice actually feed on the animal's blood. In this case, sympathy for the animal can be as much of a motivator to seek treatment as the potential economic losses caused by the infestation.

Looking for lice

"Lice are probably on cattle most of the time," says Jay Quade, Bayer representative, "but we start to see problems in the fall and winter months, due to colder conditions. Basically, when you see the lice, that means it's time for treatment."

Lice can't survive temperatures more than 100 degrees, and during warmer weather they are probably in the egg stage or in some protected, cooler area on the host, such as its ears. But right now, in the midst of fall and early winter, is the time to be on the lookout for lice.

Hoelscher says it is especially important to look for lice during a dry winter when there's less forage for grazing. If animals are already in a weakened state from lack of nutrition, it makes it more difficult for them to withstand a lice infestation.

Symptoms you'll notice

If your cattle have a lice problem, you may notice them licking their hair to soothe the irritation or rubbing up against posts, fences or trees. Even if you don't see them rubbing, you'll probably spot patches of hair on the ground or notice hair loss on the animal itself. Bill Stacey, Extension entomology specialist with the Oklahoma Cooperative Extension Service, says some of the worst cases he's seen have resulted in 1/3 to 1/2 of the surface hair being rubbed off.

Cattle will likely become restless, and the infestation can ultimately lead to a loss of gain in stocker calves or a loss of milk production in your females. Animals can become more susceptible to disease due to weight loss and stress, and heavy infestations of blood sucking lice can result in anemia or induced abortions.

"From the standpoint of economically sound management, you need to catch the problem early and treat before you incur any real losses," says Stacey. "But unfortunately, by the time you see a lot of the symptoms, most of the damage has already occurred."

Stacey actually recommends you isolate new cattle for a few days to determine if they're free of lice before introducing them to the rest of the herd. With a little practice, you can check for them in just a few seconds by parting the hair with your fingertips to get a closer look at the skin. The face, brisket, back at the shoulders, hips and tailhead area are common sites to find lice and should be checked first.

Treatment plans

If lice are found on an animal, all cattle in that pen or pasture need to be treated simultaneously to prevent the transfer of the pests from untreated animals to the treated ones.

"Most of the products on the market today are very effective against killing adult lice," Quade says. "Anything that a producer would choose with a label for lice should do the job."

Dr. Rick Machen, Extension livestock specialist, recommends establishing initial control with a spray or pour-on, and then using back rubbers as a preventative tactic.

"Rubbers are long and look kind of like a tube sock," Machen says. "You fill the inside with a product labeled for lice control and then put them in a high-traffic area. If there's an area where they rest during the day, you can tie it in a mesquite tree or between two oak trees."

Weather also determines which treatment is best to use. A pour-on or spot-on treatment is effective, easy to apply and less stressful in cold weather. Sprays are economical but are best used on reasonably warm, dry winter days.

"Although these products are effective at killing adult lice, there's nothing out there very effective at killing lice eggs," Quade says. "After the first treatment, you've pretty much killed all the adults, but in two to four weeks, the eggs they left behind are going to hatch, causing a new infestation.

"The key to lice control is retreatment," he continues. "You want to time it where you treat them the second time before the newly hatched lice have a chance to lay a bunch of eggs. Generally, the optimal time to treat is three weeks after the first treatment, and that's probably going to do the best job with a pour-on product."

Machen says one of the biggest advances in lice control has come about during the past 10 years or so with pour-on products that give you the multi-benefit of short-term horn fly control and lice protection, as well as control of the internal parasites.

"Some of the products beef producers use to control internal parasites will in fact control the sucking lice, too," Stacey says. "But those same treatments don't take care of biting lice, so it's important to properly identify which type your cattle have.

"For example, producers may use a dewormer that often does a really good job at taking care of lice, but if they seem to have a lingering lice problem, then they probably have biting lice instead of sucking lice," he explains.

Types of lice

The cattle biting louse can be found in both Texas and Oklahoma, and the short nosed cattle louse, long nosed cattle louse and little blue louse are all varieties of sucking lice found in both states. Texas also fights the cattle tail louse, another type of sucking louse found primarily in the Southeast.

Although there are some differences in appearance, all lice share a similar life cycle. (See table on pg. 132, 133.) Females attach eggs, also known as nits, to hairs on the animal, and the young lice, nymphs, appear about one to three weeks later. Developmental time of the young will vary among species and environmental conditions, which could help determine your retreatment regimen.

Even if you regularly check your herd for lice and follow the specifics of a treatment plan, you may find a couple of animals that seem to have a chronic infestation. Animals that have lice almost year-round or are the first to develop an infestation may be carrier animals.

These animals almost always spread lice to the rest of the herd, and some producers must sell them, or at least segregate them, to make any significant improvements in their lice control program.

But cattle aren't the only animals at risk. Horses can also be infested with these same types of lice. Fortunately, you can also use the same products to treat both your horses and cattle, but Hoelscher says a horse's skin is more sensitive than a cow's, a consideration to keep in mind when choosing a product for treatment.

"The big giveaway is you'll see a horse backed up to the fence, a post or tree, and it will do a lot of rubbing," Machen says. "The root of their tail may be completely devoid of hair where they've rubbed it off."

Not a new problem

Lice have plagued the cattle industry for the past 80 to 100 years, but Hoelscher says with the exception of last year, infestations haven't been as bad the last four or five years due to mild winters. The best advice is, as soon as you see the lice, treat the animal.

"It's basically just a nuisance for an old cow, but if they're out in the pasture rubbing around on everything, it denotes poor management," Hoelscher says. "Lice control is most important for growing animals such as stockers. It only costs a few cents per head, and your animals will be more vigorous in return."*