Control Lice by following a good Cattle Health Program.
Lice are small but they reduce financial returns of nearly every cattle enterprise. Even moderate louse numbers can cause calves and feeders to grow more slowly and require more feed per pound of gain. Louse-infested cows produce less milk for their calves. Cattle damage fences and bruise or scrape themselves as they rub to relieve the itching caused by millions of lice on their bodies. Blood loss from sucking lice is sometimes severe enough to cause anemia. Louse-induced anemia causes calf abortion and may even result in death of the infested animal.
The five species of cattle lice found in North America include four which feed by sucking blood. These are the shortnosed cattle louse, longnosed cattle louse, little blue cattle louse, and the cattle tail louse. The fifth species, the cattle biting louse, feeds on skin tissue of cattle and does not suck blood.
All cattle lice spend their entire lives as parasites on living cattle. When removed from cattle they live a few days at most. The females lay eggs which they glue to individual cow hairs close to the skin of their host. Immature lice are called nymphs. Each nymph sheds its outer skin three times as it grows to adulthood. Nymphs resemble adults of the same species in feeding habits and appearance.
Shortnosed Cattle Louse, Haematopinus Eurysternus
Although this species is seldom a problem on young calves, it causes more damage to adult beef cattle in the Great Plains and Rocky Mountain States than do all other lice.
Adult shortnosed cattle lice are slightly over 1/8 inch long and gray-brown in color. The eggs are hard and bone-white to brown. They require from 9 to 19 days, usually 12 or 13, before hatching. The nymphs become adults within the next 12 days. Females begin laying eggs after about 4 days of adulthood. Thus, this species completes a life cycle in about 28 days, although the time may range from 3 to 6 weeks. About one out of five lice in this species is a male. Males live about 10 days. Females live 15 or 16 days, producing one or two eggs per day.
Longnosed Cattle Louse, Linognathus Vituli
This species is opposite from the shortnosed cattle louse in that it infests calves most heavily. It is often found on mature cattle, but seldom in great numbers.
Adults are nearly 1/10 inch long. They appear quite slender, being about one-third as wide as they are long. Their head or “nose” is noticeably pointed. Longnosed cattle lice are bluish-black in color. Their eggs, dark blue and soft shelled, require from 8 to 14 days to hatch. The egg-to-egg life cycle requires 21 to 30 days, usually about 25. Females lay about one egg per day.
Little Blue Cattle Louse, Solenopotes Capillatus
This louse resembles a small longnosed louse. It is similar in color but is slightly less than 1/16 inch long when full grown. The head is bluntly rounded. The eggs are similar to those of the longnosed cattle louse, but smaller. Also, a cow hair on which an egg of this species is laid is characteristically bent at an angle where the egg is attached. Incubation requires from 9 to 13 days. Nymphs mature rapidly, and females begin laying eggs about 11 days after hatching. Few details of the biology of this species are known.
Little blue cattle lice are more common than all other cattle lice in the Delta States, the Southeast, in Oklahoma, and perhaps in east Texas. In other Great Plains States they are present but usually of minor importance except on cattle received from endemic areas.
Cattle Biting Louse, Bovicola Bovis
Although they do not suck blood, the feeding and movement of biting lice on the skin of cattle cause itching and distress. Cattle biting lice are present on most beef cattle in the Great Plains States. However, they become far more numerous on northern dairy cattle housed for the winter and stanchioned where they cannot lick themselves.
The cattle biting louse is easily distinguished from sucking lice. It is about 1/16 inch in length. The head is large, nearly round, and two-thirds as wide as the body. The head and thorax of both adults and nymphs are brownish-amber in color. Nymphs have pale cream-colored abdomens. The adult abdomen is darkly outlined and has a series of brown crossbars on a pale background. The eggs are pearly white when freshly laid and become pale brown as the embryos develop within.
Cattle biting louse eggs require from 6 to 11, usually 7 or 8, days to hatch. Nymphs reach adulthood in 12 to 21 days. Females begin producing eggs 3 days after becoming adults. A complete life cycle can occur in as little as 3 weeks, but may require a month or more. Populations of this species are usually from 95 to 99 percent female. Reproduction is accomplished by parthenogenesis, a form of reproduction without mating. Females commonly lay 30 to 35 eggs during a 4 to 6 week period. Adults survive as long as 9 or 10 weeks.
Cattle Tail Louse, Haematopinus Quadripertusus
Little information is available on the biology of this species. It is closely related to the shortnosed cattle louse and probably has similar rates of reproduction and growth. Cattle tail lice prefer to live on the long-haired portion of the tail, but are also often found on the neck and around the eyes.
Unlike other cattle louse species, tail lice are most abundant in late summer and early fall and are scarce throughout the winter. This is often the most damaging species in coastal areas of the South and Southeast, but it is absent or uncommon in the Great Plains States except for southeastern Texas.
Diagnosing Lousiness In Cattle
Lousiness is primarily a wintertime problem on cattle which are pastured in the open. Direct sunshine, rain, and selfgrooming by cattle keep louse numbers low in the thin summer hair coat.
Often one of the first signs that cattle are lousy is that they rub and scratch themselves against fences, feed bunks, trees, or other objects. In advanced cases, this may result in large patches of bare skin.
Typically one or two percent, or fewer, of the cattle in a herd may carry extremely high numbers of lice even in summertime. Production by such “carriers” as compared to non-carriers, is reduced. In Montana a detailed study from 1956 to 1959 suggested that louse control measures were probably economically justified on five percent, or fewer, of the cattle in that state. For cattle which do need treatment against lice, the returns can be substantial.
Bulls are “carriers” in a disproportionately high number of instances. This may be because bulls are housed more often than cows, because their hair is longer and more dense, and because the bull’s massive neck and shoulders prevent him from grooming himself as effectively as do females and steers.
Cattle sucking lice sometimes congregate in dense patches which may be seen from several feet away. They appear as black or blue-brown spots the size of a quarter or fifty-cent piece. Close inspection of these patches reveals individual lice, both adults and nymphs, as well as eggs. Sucking lice spend most of the time with their heads partly buried in the host’s skin as they engorge themselves with blood. In this position, with their abdomens pointing outward from the host’s skin, they cling to the animal’s hair with all six legs. They are usually difficult to disturb, although they are not so tenacious as ticks.
Cattle severely infested with shortnosed cattle lice take on a characteristic “greasy” appearance. This greasy appearance results from crushed, blood-engorged lice and their feces, from blood and serum oozing from wounds made by the lice in feeding and by the cow’s scratching and rubbing, and from the shiny translucence of thousands of living lice packed densely together.
Cattle biting lice are generally less concentrated into discrete groups. However, in heavy infestations, skin areas may become very densely populated by these small brownish-amber lice. They spend most of their time in a feeding position similar to that of the sucking lice. Biting lice are more readily disturbed and may be quite active, especially when they are numerous and when the weather is mildly warm.
When a cattle biting louse population has been thriving for some time, large areas of a cow’s coat may become burdened with several eggs per hair, the basal portions of the hairs glued together in an inseparable mat.
Even when cattle are not obviously lousy, it is desirable to inspect them for lice before purchase or as they are handled for branding, vaccination, or other purposes. Parting the cattle hair with his finger tips allows the stockman to see if lice and their eggs are present. With practice, only a few seconds are required to examine each animal in several places— neck, withers, brisket, shoulders, midback, tailhead, and behind the rounds.
Two or more species of cattle lice often occupy the same animal. However, an animal with many sucking lice usually has only a low or moderate number of biting lice, and vice versa.
Several studies have documented severe anemia in cattle as a result of shortnosed sucking louse infestations. Anemic cattle fail to gain weight, or they may slowly lose weight. They appear very weak and have extremely pale skin around the eyes, muzzle, and udder. Their red blood cells may be reduced to as little as one-half or one-fourth the normal number. Extreme louse-induced anemia causes pregnant heifers and cows to abort. Anemic cattle have low resistance to diseases and to stresses caused by bad weather, shipping, or handling. Such cattle become very exhausted and may die if forced to move even 100 to 300 yards.
Ridding anemic cattle of lice usually results in rapid improvement. Complete recovery may be achieved within a month. However, in ridding such cattle of lice one should remember that they must be handled gently and may not be able to withstand the stress of dipping or of crowding in holding pens while sprays are applied. Weakened animals are also more readily poisoned by insecticides, especially those with systemic action.
Controlling Cattle Lice
Sanitation. The primary way in which lice are spread is from animal to animal when cattle are in close contact with one another such as during feeding, breeding, or shipping. However, some lice and louse eggs drop off into bedding or are rubbed off, along with hair, onto fences and feedbunks. These die in a few hours in cold weather; but in warm weather the lice may live for several days if not exposed to direct sunlight, and some of the eggs may hatch. Other cattle may then become infested from contaminated bedding, bunks, sheds, or trucks. For this reason, premises vacated by infested stock should either be disinfected or should stand empty for 10 days before being used by clean stock.
Newly purchased stock should be isolated and treated for lice before being added to the herd.
Herds routinely treated against cattle grubs, ticks, horn flies, or face flies, may not develop louse infestations which warrant treatment. When cattle are to be treated for lice, it is important to consider what other insecticides or medications have been, are being, or will be used on the same animals. Multiple treatments or combined effects of different treatments may cause toxic reactions in livestock. This is especially true of the organophosphates with systemic action, which are popular in grub control programs. If grubby cattle are to be treated for lice or other pests, it is wise to do one of the following: 1 ) treat early in the fall with timing and insecticide selected to kill the cattle grubs also, or 2) if it is after the safe date for using systemic insecticides against grubs, use only a nonsystemic insecticide against the lice.