SYMPTOMS OF BOT-FLY DISEASES.—The larvae of the bot-fly of the horse do not cause characteristic symptoms of disease. Work horses that are groomed daily are not hosts for a large number of "bots," but young and old horses that are kept in a pasture or lot and seldom groomed may become unthrifty and "pot bellied," or show symptoms of indigestion.
Cattle suffer much pain from the development of the larva of the H. lineata. During the spring of the year, the pain resulting from the presence of the larvae beneath the skin and the penetration of the skin is manifested by excitement and running about. Besides the loss in milk and beef production, there is a heavy yearly loss from the damage to hides.
The parasitic life of the bot-fly of sheep results in a severe catarrhal inflammation of the mucous membrane lining the sinuses of the head, and a discharge of a heavy, pus-like material from the nostrils. The irritation produced by the larvae may be so serious at times as to result in nervous symptoms and death.
TREATMENT OF BOT-FLY DISEASES.—The treatment of the different bot-fly diseases is largely preventive. This consists in either the destruction of the eggs or the larvae.
The different methods of destroying the eggs of the bot-fly of the horse are clipping the hair from the part, scraping off the eggs with a sharp knife, or destroying them by washing the part infested with eggs with a two or three per cent water solution of carbolic acid. This should be practised every two weeks during the period when the female deposits the eggs.
Housing the cattle, or applying water solutions of certain preparations to the skin that may keep the female from depositing eggs, may be practised for the prevention of the ox-warble. The most practical method of ridding cattle of this pest is to destroy the larvae. This can be done by examining each animal and locating the swelling or warble and injecting a few drops of kerosene into the opening in the skin. A better method is to enlarge the opening in the skin with a sharp knife, squeeze out the grub and destroy it. This should be practised in late winter and early spring.
The application of pine tar to the nostrils of sheep is the most practical method of preventing "grub in the head." This should be practised every few days during the summer months. A very good preventive measure is plenty of shade for the flock. Valuable animals may be treated by trephining into the head sinus and removing the "grub."
LICE.—The sucking lice belong to the genus Hoematopinus, and the biting lice of mammals belong to the genus Trichodectes. Different species of sucking and biting lice occur on the different species of farm animals. Poultry act as hosts for many different species of biting lice belonging to the following genuses: Lipiurus, Goniodes, Goniocotes and Menopon.
The common sucking lice occurring on animals are the large-headed horse louse, H. macrocephalus; the long-nosed ox louse, H. tenuirostris; the large-bellied ox louse, H. curysternus; the H. stenopses of sheep; H. suis of swine; and the H. piliferus of the dog.
The common biting lice (Fig. 63) that are found on domestic animals are the T. pilosus and T. pubescens of solipeds, T. scalaris of the ox, T. spoerocephalus of sheep and goats, T. latus and T. subrostratus of the dog and cat. Menopon palidum, Lipiurus variabilis and Gonoides dissimilis are the common lice found on poultry.