THE SHEEP MAGGOT.

Manawatu Herald, Volume XXX, Issue 3784, 4 February 1908, Page 3

THE SHEEP MAGGOT.

Important to Farmers.

(By J. A. Gilruth, M.R.C.V.S., F.R.SiE , Chief Veterinarian).

During the past summer this pest to the flcckowner was proved to exist in New Zealand, and though, as yet, recognised only in North Otago, in view of the fact that it is in many parts of the world a veritable scourge', sheep,owners are cautioned to be ou the lookout tor its appearance' among their flocks, and to take all possible precautions to prevent its, spread, as well as its ravages. If in older countries with small flocks, under constant supervision, the maggot iu certain seasons is a constant souice of worry and loss to farmers, how much more serious rui&ht it not become in, the Dominion, where flocks are larger, and are not, and could only with difficulty be, subject to the same watchful care! This is well seen in certain parts of New South Wales and Victoria, where of recen t years a species of maggot-fly (the nature of which is apparently not yet definitely determined) has been playing havoc with sheep, and to such au extent that some reports mention 10 per cent; of cases as having occurred amongst certain flocks of ewes. description. The fly which we have demonstrated to be present here by hatch-' ing it from the larvae (maggots) is that termed Lucilia sericata. Smaller than the ordinary “blue bottle,” it is of a greenish-blue tint, .but is otherwise similar in appearance, and is frequently confounded, with that fly. In most countries where the sheep-maggot is plentiful • the parent is popularly considered to be the common “ blue . bottle” (Calliphora vomitoria), but this is erroneous. The “blue bottle” lays its eggs on carrion, and like material, on which the lavae feed after hatching, but there is no evidence that they are capable of existing and developing ou the live animal; at least, they are not capable of penetrating the healthy skin. If they were, it is obvious that sheepbreeding would have become almost an impossibility in New Zealand long ago. The sheep-fly lays its eggs in the wool of sheep particularly those whose wool is dirty, lambs and hoggets suffering from diarrhoea and consequent soiling of the hind quarters being especially prone to attacks. Sheep and lambs which are free from soiled wool, are not, however, exempt from attacks when the fly is prevalent during the summer months, particularly towards the latter end of the season.' Showery weather, and long grass ou dewy mornings, rendering the wool moist, seem to exert an influence in attracting the fly. Naturally, wounds and abrasions of the skin are also likely places of attack. Although the sheep is generally considered to be a necessary host for the maggot, it is difficult to see how this can be so, and it is most probable that any carrion iu warm weather may offer a suitable place for the deposition of the eggs by the female fly, and the subsequent development and growth of the larvae or maggots. Dead sheep, especially those left unskinned, in any case afford an excellent breeding ground for the parasites, so that one of the first lines of defence is burial of all dead sheep so soon as.found.

In a comparatively short time after the eggs are laid the young maggots are hatched out and immediately travel towards the skin, where they induce irritation and inflammation, which is only aggravated by the attempts of the animal to obtain relief. Soon the maggots burrow through the skin and pass between 'that and the muscles, and if not observed early they will ultimately burrow very deeply, cases having been seen by 'the writer in which they have eaten their way right into the abdominal cavity before death of the animal occurred. SYMPTOMS. The smyptoms consist, as may be expected, of attempts to remove the cause ot the irritation by biting the part affected, frequent rubbing, rapid agitation of the tail, etc, ; but this can generally only be observed if the animal is undisturbed, and in the early stages before the skin becomes insensible. If the skin has become partially destroy.! before the affected sheep is seen, listlessness may be the only readily discerned evidence, but a careful observer may —especially if the animal is attacked in the side, as lambs frequently are —detect a damp, dirty-looking patch of wool due to discoloration by exudation from the skin. So rapid is the whole course of events that, even in a carefully watched flock, casqs of extensive' damage are not rare, and sometimes even death is impossible to prevent. PREVENTIVE MEASURES. , In additional to the burial of dead sheep—’which, by removal of a breeding-ground, prevents the increase of flies to a great extent — cleanliness of wounds and the proper antiseptic treatment, the maintenance of cleanliness of the hind-quarters’ wool by crutching, dagging, etc., where necessary, go far to prevent the fly “ striking.” Diarrhoea should be treated by {removal to a different pasture, and, 1 if necessary, the provision of dry food.

In addition to all this, dipping by means .of an effective lasting dip as a preventive is strongly re? commended for any flock in which

the trouble has appeared, or is likely to appear.

CURATIVE TREATMENT

This should be adopted immediately a sheep is observed to be “blown.” All dirty or matted wool should be removed by the shears, and a strong solution of non-poisonous sheep-dip or other similar antiseptic applied to the part, where the maggots are located. A good mixture for the purpose is one part of oil of turpentine to three parts of olive-oil, the whole being well shaken up before applying. The greatest care is necessary in order to destroy all the maggots, as whenever the wool is disturbed, and especially when it is being clipped, they immediately endeavour to bury themselves amongst the, surrounding wool. It is always advisable, therefore, to examine a dressed animal on subsequent days in order to ascertain if any maggots have escaped, and especially to be certain that it has not —as frequently happens —been again “struck,”