The Bot Fly

Feilding Star, Volume XIV, Issue 117, 23 March 1893, Page 4

The Bot Fly

LEAFLET No. 3. So many harmless insects of various kinds have been sent in under the impression that they were 'horse hots' or •horse bees/ that it has been thought de* sirable to issue this leaflet as an aid to settlers in the identification of the true bot. Descriptions of the successive stages in the devolopnient of the fly are not given. The eggs are deposited on the hair of the horse, usually on the inner side of the knee and foreleg, on the shoulder, the mame, and on the long hairs under the lower jaw. Tbey are yery firmly attached to the coat by a strong glutinous substance, and remain so. till hatched by the warmth of the horse's body, aided by the moisture of his tongue as he licks himself. The tiny maggots aro taken into the mouth by the tongue, and are swallowed with the food. They then, by means of hooks, attach themselyer firmly to the lining of the stomach. In this position they re* main for about nine months, at the end of which time they are nearly fullgrown, and; about fin., long Iv the spring they loose tluir hold, and are voided along with the excreta. By means of tht* bristles attached to their sides tliey immediately burrow under the manure, into the earth, or -under any other shelter, where the change to the chrysalis state is undergone. From the chrysalis the perfect flies emerge! in about six weeks, during the summer. Symptoms. —Horses suffering from a severe attack of the parasitic larvsc usually show somo of the following symptoms: They lose flesh, go off their feed, and sometimes bite their sides, cough, huve difficulty in breathing, and ■tiffness in the joints, followed in some instances by convulsions. Mr H. Thompson, M.R.C.V.S , says : " I have never seen the stomach entirely perforated, but the irritation induced by the development of the larvae causes in many cases a groat wasting of flesh in the horse." If in doubt whether a horse is infested with the bot fly larva;, Dr Prankish, of Christchurch, recommends : " A quarter of an ounce of aloes mixed with half an ounce of shag tobacco, moistened with treacle, made into a ball and given lo the animal." He says that if any of the larva; are present some will become detached, and will be seen in the droppings. The larger dose ho prescribes below should then be administered : — " Three ounces of shag to« bacco, moistened with a littlo glycerine or treacle, to which half a teaspoonful of cajeput bas been added, should be made into balls, and the whole given ns a dose. Two hours afterwards half a pint of linseed oil in a pint of gruel should be administered. If notice is taken of tho evacuations, the larva? of the bot-fly will be easily seen. The above is for a hack. Half the quantity is the dose for a pony, double for a draught-horse. This system of treatment has been found successful when tried early, and is therefore beyond the region of experiment." It is desirable that the long hairs on the lees and under the iaw should be cat off. Working horses should, after being proomed, bn rubbed over with carbolised oil, kerosene emulsion, or other substance obnoxious to flies. The best agent for this is Little's dip. ono part of dip in from 20 to 25 parts of water. Where horses are kept in numbers the wash may be applied by yarding the animals and using a spraying-machine with clyclone nozzle, such as is found in every wellmanaged orchard. Tbe mistake spray will permeate the coats of the horses, and while its effect lasts no fly will attempt to deposit her eggs on them. One application per week will in most cases prove sufficient. In paddocks where affected horses are kept it is a very good plan, if larva; are observed in the droppings, to collect and burn the excreta, the only sure way of killing the larva), thus preventing the emergence of numerous flies, and tho laying of many hundreds of eggs.