Fig. 9.—Red louse (Trichodectes scalaris) of cattle. Enlarged. (From Bureau of Entomology.)
When a considerable number of animals are to be treated the most satisfactory method of destroying lice is by the use of a dipping vat. Two dippings should be given 15 or 16 days apart. Dipping in the fall is good insurance against risk of loss from lice during the winter. All animals in the herd should be treated regardless of the number showing infestation. Either coal-tar-creosote or nicotin dips may be used. These are sold under various trade names. The directions for dilution given by the manufacturer should be carefully followed. As coal-tar-creosote dips do not mix well with all kinds of water, they should be tested with the water to be used for making the solution by mixing some of the dip in the proper proportions with the water in a clean and clear-glass bottle or jar. If an oily layer or mass of globules collects either at the top or the bottom of the mixture after standing an hour, the dip is not suitable for use with that kind of water. Imperfectly mixed coal-tar-creosote dips are liable to poison animals even when not used in stronger solutions than that recommended by the manufacturers, and are also likely to be inefficacious.
Fig. 10.—Egg of short-nosed blue louse (Hæmatopinus eurysternus) attached to a hair. Enlarged. (From Bureau of Entomology.)
The lime-sulphur dip, which is highly efficacious as a mange remedy, is of little value for destroying lice, especially blue lice. The arsenical dip used in tick eradication is a good louse remedy, but its use is not advisable on account of its poisonous nature, except under the supervision of capable persons who know how to use it and what precautions to take.
MANGE, ITCH, SCAB. [17]
Cattle are subject to four kinds of mange, of which common mange or psoroptic mange is the most important.
