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.

Sucking Lice
     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.

Biting Lice
     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.

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