THE HOUSE-FLY.

Clutha Leader, Volume XXXVI, Issue 51, 7 December 1909, Page 2 (Supplement)

THE HOUSE-FLY.

A DANGEROUS PEST. That tho most dangerous animal on earth is the common and despised house-fly is the conclusion, not of seu-•sation-mongers, but of cool-headed and cautious scientific investigators, writes Frank i'leisehmun, in 'Harper's Weekly.' It is by a jury of experts drawn from most of' the principal cities of the United States and Canada that this decision has been reached. The caso was that of the People versus Musea Domestica—otherwise the common house-fly; and by this verdict tho defendant has forfeited all right to life and liberty.

"Hitherto the fly has been regarded complacently as a harmless nuisance and considered to be an annoying creature with great persistence and excessive familiarity," said Dr Daniel D. Jackson in a paper read before the joint convention of the American Civic Association and tho National Municipal League at Pittsburg. "Regarded in the lfghfc of recent knowledge, the fly is more dangerous than the tiger or the cobra. Worse than that, he is, at least in our climate, much more to be feared thun th'o mosquito, and may easily be classed, the world over, as the most dangerous animal on earth." T'lio fly has been found guilty, in fact, of being tho chief agent in the transmission of numerous bacteria, including those of tuberculosis, but principally tlio bacilli of typhoid and intestinal diseases. That flies are carriersof disease has been recognised by sanitarians for a dec'ade or more, but it is onh during the last two years that the ex tensive investigations have been undertaken which have exposed the constant danger to health which these pestt convey —and which have also, fortunately, demonstrated tho ease with which flies may be eliminated from properly-kept households. Although Celli had shown, in 1888, that Hies formed, a medium for the transmission of typhoid bacilli, it was in 1895 thai Mr George M. Kober, |iealth officer of the district of Columbia, lirst suggested that many cases of typhoid fever might bo due to theii transmission of infectious matter to the food supply. In 1897 Dr Wallace Clarke, health officer of Utica, New York, traced an abnormally high proportion of contagious diseases in the eighth ward to the presence of an insanitary garbage-dump, upon the removal of which tho death rate was reduced to normal. Tho mortality from typhoid during the Spanish war made investigations along these lines more general. It was shown "that every regiment constituting the First, Second, Third, Fourth, Fifth, and Seventh Army Corps developed typhoid fever, • and that more than 90 per cent, of the volunteer regiments developed it within eight- weeks after going into camp. More than four-fifths of tho total number of deaths were caused by typhoid fever, and infected flies were directly responsible for the spread of the disease.

That the autumn increase in the number of typlioid fever cases, whien occurs ui most cities, and the enormous .summer doutn-rato of children, are both duo to the common lly was made clear by a committee appointed by tlie ivLerchants' Association oi .New York in 11)07 to prevent the increasing pollution of tile inland waters of the .State. It was proved conclusively that/whorcver the water si: ly is not itself contaminated, the i ase-lly is the chiel source of typhoiu revyr and other intestinal diseases, which are caused in tais case by the transmission of the germs of exposed faecal matter to the lood used for human consumption.. By the use of staining fluids the flies were shown to bo in constant transit between faecal matter in outhouses and the food iu near-by restaurants and homes. Microscopic examinations showed that these flies convoyed quantities of bacil-lus-laden material upon their mouths and legs, and deposited them wherever they walked.

So much interest was aroused by the publication of the committee's report that it was resolved that immediate measures should be taken to awaken public sentiment by securing the testimony of tho health officers and principal sanitarians in this country and Canada. The replies received in fosponso to a circular letter sent out by tho Merchants' Association, while ascribing a varying degree of importance to tlie role played by iiies, were practically unanimous in admitting their agency in the dissemination of intestinal diseases.

different varieties of Hies are found in our houses, 08 per cent, of which are represented by the common house-ily. Flies lay their eggs only in fermenting or decaying substances—by preference in horse manure. Hence every stable is a centre of infection unless periodically disinfected.' The fly maggot is also hatched out in latrine's and ash-pit refuse, such- as bedding, straw, rags, paper, scraps of meat, fruit, etc., on which substances the Jarvao subsist after they hatch, which occurs in about 12 days after the egg has been laid, it is estimated that a single fly, laying 120 eggs at a time, will produce a progeny amounting to sextillions by the, end of the season. The number of bacteria upon a single fly have been proved to range all the way from 550 to 6,600,000. The averago for 414. flies which were examined at the Agricultural Experiment Station at Storrs, Connecticut, last year was 1,250,000 bacteria apiece. This represents about the number of bacteria. that enter the human system when one swallows a glass of liquid into which some fly has perhaps fallen, to be removed by a slovenly waiter without the liquid being thrown away. By screening and quickly disposing of all refuse, and disinfecting such as cannot be removed rapidly with crude oil or atoxyl, Paris green or chloride of lime, (lies can be prevented from breeding and thus eliminated from any locality. In further effort windows and doors should he screened, foodcovered up, and pyrethrum powdey burned wherever flies congregate. "Even if tho typhoid or house-fly were a creature difficult to destroy, the general failure on tho part of communities to make any efforts whatever to reduce its number could properly be termed criminal neglect," writes I)r L. 0. Howard, Chief of the Bureau of Entomology at Washington. "But since it is comparatively an easy matter to do away with the plague of flies, this neglect becomes an evidence or ignoranco or of carelessness in regard to disease-producing filth which to the informed mind constitutes a serious blot ©a civilised methods of life," <