ENTOMOLOGICAL.

Otago Witness, Issue 2010, 1 September 1892, Page 5

ENTOMOLOGICAL.

HYPODERMA BOVIS. (OX BOT FLY OR WARBLE FLY.) There has for some time been a disposition on the part of several farmers in some parts of New Zealand, to attribute the death of various horses to the action of what is commonly called -lot" flies, and the fact of a great number of these insects being found in the Btomach of dead horses is., taken to be a proof of their having caused death. This, 5 however, is certainly no evidence, because, as Miss Ormerod says, she has seen them so thick in that position that another could hardly find room there. However, that is not what is now intended to be dea.lt with, Some persons are apparently trying to get up a scare by asserting that the bots attack swine, laying their eggs in" the skin, and that we may expect them to attack jnen next, because they are well known to do so elsewhere, and accounts of such things have been published by scientific men and cannot be denied. Now this is all a mistake, and quite absurd. The fact is, that the common name of bob fly is not correct, although ifc is in general use even amongst veterinary surgeons. A bot fly properly so-called (if the term can be applied to' popular names) is not the (Estrtis equii, or horse fly, but the (Extras or Hypoderma iovis, the ox skin. fly. This fly in the larval stage lives under the.cuticle in a nasty u'cer caused by its presence, and with an opening through which it breaths. But as yet there is "no reason whatever to suppose it is in the The reason why the term bot fly is applied to this insect is because tho lumps or .bosses in which its larvce live are called botts ( land no doubt some one who is not aware of jthis has read in some entomological work of the fact that bot fly larvae have be'en an«l occasionally are found in the human skin, where they cause much suffering and anuoy,ance, but the horse fly is not fitted either by its habits or its construction to burrow under the skin of a man or other animal, nor could it live there if it did. What has been seen (by the writer himself) in the skin of pigs is the egg of a species of ichneumon fly, which normally attacks the larva of certain moths, and it is by no means very uncommon to find eggs' in that position when tho hogs have been scalded and out up for bacon or other uses. This kind of bot fly, or what may be considered the properly so-called fly, has often been known to frequent tho' human body. They burrow often to a long distance, and cause great irritation and pain, generally settling down about the head, the neck, or tho shoulders, but in no country are they so common as to be a general cause of alarm to the inhabitants, and no one need be apprehensive of such a thing in Now Zealand, because there is no reason to believe that the fly is either here or at all likely to arrive. Respecting this fly ib is somewhat curious that up to a late date all eutomologists were of opinion that it deposited its eggs either upon or in the skin of the ox family, but of late, the famous veterinary surgeon, Dr Cooper Curtis, has claimed the discovery that the fly deposits her eggs on the lip of the ox,, and the newly hatched worms enter the animals mouth, and reaching as far as the oesophagus, penetrate the cesophagal walls, and burrowing their way through the muscular tissues, reach the skin of the back, where they raise their botts. These insects are the cause of euormous losses, both in the hides and in the beef of animal*. England alone ha* been stated to have lost annually some seven million pounds from them, until thtj unvceaTkd exertions of Miss Ormerod in discovering remedies, and in overcoming the farmeis' reluctance to use them, have reduced the loss to a probuble seventh. The persons who suffer from the fly attack are nearly in every case those who attend upon cattle. At all events the Ili/poiferma bovis (or bot fly proper) has no conception with our imported horse fly, a.ud if faunen»are determined (in opposition to the opinion of" our most skilled and experienced scientific men) to attribute the death of their horses to these flies, they need not make matters worse by accusing them of doing mischief that they are incapable of. In short, there are three quite distinct flies. * (1) The horse fly ((Estrus equii) which attacks the horse, (2) The ichneumon fly, which sometimes abnormally attacks the pig, and (3) the (Estrui

or Hi/podinaa lovis which attacks horned cattle and sometimes (abnormally) men, and which is not supposed to be here.

Entomologist.