BOT FLIES OR BREEZE FLIES.
—The larvæ or grub of all common bot flies are thick, fleshy grubs and pass their life in some portion of the body. When they are fully developed they leave the body by some route and bore into the ground, where they go through another stage of their development known as the pupa stage. When this stage is completed they crawl out of the ground as a fly ready to deposit eggs.
Horse Bot Fly.
—Everyone is familiar with the common nit fly and the yellow nit that is attached to the hair on almost all parts of the horse, but especially on the chest and legs. The young larvæ or even the egg may be transferred from these regions of the body into the mouth by the horse biting these parts. The grub passes into the stomach where it attaches itself to the mucous lining and continues its development. The bot is not so dangerous as it is popularly supposed to be. They may, when attached in large numbers to the right side of the stomach, interfere with digestion and be responsible for some of the digestive disorders and colics. They are uniformly present in the stomach of all horses that are kept in the open where flies can get at them. A carefully groomed animal may be free from them. The eggs may be destroyed by rubbing the body with a rag wet with kerosene. One of the most common remedies for bots, and at the same time the most useless, is a mixture of molasses and milk. Bots are hard to dislodge from the stomach until they have completed their development there and pass out of their own accord. Half-ounce doses of turpentine three hours apart until three doses are given, followed by an ounce of powdered aloes as a physic, is a good remedy and easily administered. Mix the turpentine with half a pint of milk or gruel and give on an empty stomach. Carbon bisulphide is a good remedy. Take two drachms or one-fourth of an ounce of this and shake with a pint of cold water and drench. Repeat this every two hours until an ounce of bisulphide is given, then give a physic of aloes. These remedies should be given on an empty stomach.
HORSE BOTS IN STOMACH
The bot fly lays its eggs on the hair of the horse. These, taken into the stomach, hatch out and give rise to horse bots or young maggots that attach themselves to the walls of the stomach. After becoming grown they loosen themselves and pass out with the feces.
Bot-Fly of Cattle or Warbles.
—It is now believed that eggs are deposited near the feet and that the grub is taken into the mouth and becomes partially developed in the digestive tract. It then burrows through the tissue until it reaches the region of the back. The only treatment that will amount to much is to destroy the grub as it is developing under the skin. If farmers and stockmen will systematically do this they can soon lessen the damage done. The heel fly annoys cattle, and the grub, when it escapes from the back, leaves a hole in the best part of the hide, causing loss in this way. After the grubs are in the back no treatment helps the animal very much; but the grub can be killed, thus preventing their developing into flies that would annoy other cattle. The grubs may be squeezed out and destroyed. Mercurial ointment may be rubbed through the hole and kill the grub, or chloroform, or creoline, may be injected into the grub with a hypodermic syringe. It does not require very much time to look after the number of cattle usually found on a farm.
The Bot-Fly of Sheep
is a very troublesome pest at times, and always causes trouble and annoyance to the flock when present, and occasionally causes considerable financial loss. The fly attacks sheep during the warm months, July and August generally being the worst. The presence of fly in the flock is easily told by the behavior of the sheep. The fly looks much like a house fly, only it is longer and it always attempts to lay its eggs just inside of the opening of the nose. As soon as the fly begins to get near the nostril the sheep will begin to run, will hold their noses close to the ground, and frequently huddle together as closely as possible for protection. When the fly does succeed in depositing the larvæ it begins immediately to work its way up the cavity of the nose and finally gets into the small cavities in the head, where development goes on. It is during this period of development in the head that most of the damage is done. As the grubs grow larger a discharge from the nostril is noticed, which may soon become very thick and sticky, gumming up the nostrils and making breathing difficult. The sheep will often carry their heads low, but will frequently raise their heads and point their noses straight up.
The treatment may be either preventive or surgical. The first is within the reach of everyone owning sheep. Where only a few sheep are owned each individual should be caught and a mixture of tar and lard, or oil of tar and lard, applied to the nostril with a brush. This can be done in a short time and should be repeated every ten days or two weeks during the warm months. Narrow salt troughs may be made and the edges smeared with tar so that the sheep will get tar on their noses when they take salt. Turpentine may be applied high up in the nostril by means of a feather. Begin the preventive treatment early in the spring or whenever you know by the action of the sheep that the fly is bothering them, and you will have better success than to wait until the sheep are affected and undertake to cure them.