THE BOT FLY.

Otago Witness, Issue 2688, 20 September 1905, Page 6

THE BOT FLY.

This fly is a very prolific layer, but by far, the greater number of 'the larvaj emerging from the eggs are destroyed before they 'reach the stomach of the hoxse by being crushed during mastication. Probably not more than one out of every 50, or eA'en one out of every 100, may reach its destination. However, ■when once they succeed in fastening themselves to the wall of the stomach they remain safe in that situation till they voluntarily detach themselves. No medicine vrill affect them, ■which is attributable to the great resisting power of their vestment and their method of feeding. As long as the bots are only attached to the left side of the stomach, nor too numerous, they.do not seem to incommode the animal vrry much, and even are supposed to assist in the digestion by causing a gi-eater secretion of gastric juice. We cannot do better than quote Professor James Law (the "Farmers' Veterinary Adviser") on this subject-. — "The disturbance they cause depends on theii numbers and the portions of the canal on which they attach themselves. In . the throat they produce a chronic sore throat and discharge from the nose, which continues until the following spring, unless they are previously evxtracted with the hand. In the left half of the stomach, which is covered with a thick insensible cuticle, they do little harm when in small numbers, hence Bracy Clark supposed them, to be rather bene,ficial in stimulating the secretion cf gastric juice. When very numerous, and aoove all, when attached to the highly sensitive right half of the stomach or tne duodenum, they seriously interfere with digestion, causing the animals to thrive badly, to be weak and easily sweated or fatigued, md even determining sudden and fatal indigestions. This last result is especially liable to occur in spring or early summer, wh-^n the bots are passing out in great numbers ond hooking themselves at intervals to the coats of the sensitive bowels in their cuurse. They will sometimes accumulate in such numbers as actually to block the passage. rkey even attach tliemselves to <ite skin outside the anus, causing the animal to go awkwardly, to switch his tail and give other signs of extreme discomfort, until the tail is raised and the offender discovered and removed." Mr W. Williams ("Principles and Practice of Veterinary Medicine") says: — "That bots are capable of giving rise to severe diseases in the horse there cannot be any reasonable doubt, but it is not often the disorder is correctly diagnosed, since it is only by passage of the larvre, or by the adherence to the verge of the anus, that the practitioner can be made aware of thenpresence." Mr J. S. Woods, V.S., luv& luiblighed in the Veterinarian a case, pi

tetanus in a mare associated with the laivss of bats, and Mr J. T. Bicwer, V.S., lias also given a case in the same journal, ! where the duodenum of a horse \t as perforated by bots. — Remedies and Preventives. — To try and remove tlio bots by medicinal treatment after they are properly fixed to the stomach is labour in vain. They resist stronger poisons than Avoukl be safe "to administer to the horse, t\ hich, as is known and has become proverbial, can stand very strong doses. Professor Lpw is very strong on this point: — "'We cannot certainly kill the bots m the stomach, as they will resist the strongest acids ;>nd alkalies, the most irrespirable and poi&ouous gases, the most potent narcotics and mineral poieons empyreumatic oils, etc. Oil of turpentine, bryony, ether, and benzine have beer: relied on by different practitioner*, t but none of them are quite satisfactory. Tb | seems probable that these, like other veimifuges, will act best in autumn or earlywinter, before the larvae have acquired their hard, horny coat, of moil, and at this time according!} 7 they may be given with more confidence. The azedarch (pride of China), grown lound stables in the South (England, R.H.) .to protect from bots, probably acts in this way, if at all,- being cropped and swallowed by the animals while the bots are slill white, soft, and permeable to liquids." Other authorities are also strong in their expressions as regards tlie resisting faculties of bots. 'I he j only time promising an effective removal ! of the larvse :s when the^e are yoang mid i still covered with a ie.ss impervious vost- | rnent tknn is the case after several months. i A powerful drench soon after a horse has become infested may prove of great service, | and the proper time for administering such j medicine would probably be about early summer. It would be inadvisable to give I heie formulas of "recipes which ought to | be eclmini&tered only on the advice of a veterinary surgeon, after diagnosis of the disease. - Preventives are the only safeguard against the ill effects produced by bots. Horses | which are constantly handled are easilyprotected. Mere cleacliness — washing and grooming — will prevent the larva* loaching the stomach of the horse. The long hairs below the jaw and at the base of the neck, between the legs, etc., should ba cut away to prevent the fly settling with eis© and depositing her eggs-. Washing the shoulders, flanks, and other favourite parts visited by the 3y with soft soap and water will effectively remove the eggs. Horses running in packlocts should occasionally be caught, washed, and groomed, and their sioulders, base of neck, forelegs, in fact, as far as the- horse can< lick itself, smeared over with oil, whale oil preferable, with a little carbolic, the crude, strong smelling added. As long as the smear lasts the fly will not settle on the horse. The removal of the long hairs is important, as their absence will frustrate the successful ovipositing.