The House Fly a Poisoner


The House Fly a Poisoner


The House Fly a Poisoner


From Technical World

IT HAPPENS every day, and so one pays very little attention. May be it is the butter, or perhaps the slice of bread alongside one's plate. Or else, quite possibly, it is the milk in the pitcher. But, whatever it is that attracts the omnipresent fly, its appearance, as it crawls over the food on the table, is unappetizing.

This sort of thing seems to be unavoidable-—wheiefore the person who deems himself philosophical puts up with it patiently. Flies are an annoyance, of course; they are even a nuisance—but, aside from the obvious precautions of window-screens, what is one to do? They are a kind of continuous plague that has always afflicted mankind, and presumably will afflict him in the future.

Here, expressed in a few words, is a pretty fair statement of the attitude of the people at large in regard to house-flies. It represents a combination of ignorance with an indifference springing from long habit. But, before going further, let us consider the facts about the above-mentioned fly, which, having tasted the butter and sampled the bread, is now by way of drowning himself in the milkpitcher.

Is the insect a desirable table guest? Well, hardly. Annoying? Yes, of course. But this is a trifling matter, relatively speaking. It is not only likely, but altogether certain that the fly in question has recently been walking over some sort of unspeakable nastiness. and that his feet in particular are covered with putrefactive, and other objectionable germs—which, as a matter of course, are freely transferred to the butter, the bread, or any other food over which the insect crawls.

Unfortunately, a fondness for human food apd drink is not the only weakness of the house-fly. Filth of all kinds has for him an irresistible attraction ; and it is this commingling of tastes that renders him so dangerous. Above all things, he seems to delight in feeding upon the waste products of the human bodv, and in this way it is that he exercises so important a function as a carrier of typhoid fever.

The health authorities of New York City estimate that about one-half of the deaths from typhoid in the metropolis annually are attributable to the distribution of the germsby flies. But, serious as this matter is, it is of vastly less importance than the destruction of human life, particularly that of young children, by the bowel complaints which these insects are chiefly instrumental in spreading. It is reckoned that deaths from these latter maladies in New York would be reduced from 7.000 to about 2.000 a year if proper precautions were taken to prevent the bleeding of flies.

In view of these facts, and of others presently to be recited, it is not surprising that some communities, notably Washington, should have begun crusades against the fly pest. People in many parts of the country are beginning to wake up to the fact that the insect is not merely a nuisanee, but a menace to health and life. Health boards in various cities are taking action ; some of the state boards of health are doing likewise; and the Federal authorities are co-operating by every means in their power—the great object in view being to arouse public sentiment on the subject by making the facts widely known.

Publicity is what is principally wanted. It is a question of educating the people on the subject—of making clear to them the mischief done by house-flies, and the ease with which the pest can be done away with by the adoption of a few simple precautions. Only the other day a large poster-sheet was issued by "the state board of health of Florida, intended for wide distribution and to be tacked up in all public places—the printed information on it being rendered more impressive by a vividly-drawn series of pictures showing flies winging their way directly from garbage cans, heaps of filth, and other sources of pollution, to the food on the dinner-table, the baby’s milk, and the bedside of the • typhoid fever patient.

It is, in short, an anti-pollution crusade that has been begun. The people must be made to realize that the house-fly is, of all existing creatures, the most dangerous to mankind. AY hile—owing to the cause above mentioned—it makes a specialty of intestinal diseases, it is also a carrier of tuberculosis. Tuburcular material, like any other nastiness, attracts the insect, and for this reason, should be carefully protected from flies. Otherwise, they will carry the germs to the kitchen and the table, depositing them upon food.

To protect all kinds of foodstuffs from flies is now realized to be of utmost importance. Indeed, the ominous buzzing so frequently heard in the pantry is far more to be dreaded than the high-keyed note of the mosquito in the sleeping-room above For there is no such thing as a clean house-fly ; the insect, bred in filth, is always a carrier of microbes. Microscopic examinations made by the health authorities of New York City, in 1907, showed that the average fly among 414 of the insects caught between July 27 and August 20, the height of fly time, carried on its body 1,222,570 bacteria.

These experiments indicated that the number of bacteria on a single fly may range all the way from 550 to 6,660,000. As summer advances, the number of germs per insect rapidly increases. The method adopted was to catch the individual fly with a sterile fly-net, introduce it into a sterilized bottle of water, and shake the bottle to wash the germs from its body—the result being just about what would happen if the fly had fallen into a jug of milk. Some of the flies were captured in cow stables, pig-pens and swill-barrels. It is from such favorite haunts that they come direct to our kitchens and dinner-tables.

So conspicuous is the house-fly as an agent for the distribution of typhoid fever that the government bureau of entomology suggests the appropriateness of calling it the “typhoid fly.” Beyond question it was mainly accountable for the outbreaks of this deadly disease in our military camps during the war with Spain, in 1898. Every regiment developed typhoid within eight weeks after assembling in the encampments, and in every one of the camps, in the North, as well as in the South, the malady became epidemic.

From first to last, one in every five of our soldiers in the national encampments developed the disease, and of the total deaths more than eighty per cent, were caused by typhoid. It was the flies that did it. Indeed, they were seen walking over the food in the kitchen tents and mess tents with their feet visibly whitened by lime from the camp latrines. Every man sick from typhoid became a fresh source, through the medium of the insects, of infection for his comrades. In autumn, as the weather grew cooler, the flies gradually disappeared, of course, and the disease diminished proportionately with the death of the pernicious pests.

Thus was furnished a very striking object lesson in the relation between the house-fly and typhoid fever. But there is plenty of other evidence. Physicians hitherto have been accustomed to regard as inevitable what they call the “fall rise” in typhoid deaths—that is to say, the marked increase in the number of such deaths in the autumn of each year. But it is noticeable that if the time be set back two months, from the report of death to the contraction of the disease, it exactly corresponds to the period when flies are most numerous and active. In other words, the flies do the mischief, and about sixty days later the victims perish.

The diarrhoea, summer dysentery, and other intestinal complaints which carry off so many young children in hot weather have always been attributed mainly to temperature. But it is now realized that this was a mistake. The diseases in question are so prevalent at that time of the year because it is then that flies are most numerous. They are caused by specific and well-recognized germs, which the flies distribute. Hence— as is now for the first time understood —the relative immunity of breast-fed babies to such complaints, as compared with infants artificially fed, whose food is more or less exposed to the dangerous insect.

It would be incorrect to suppose that flies are alone responsible for the distribution of typhoid fever. There are other sources of infection, notably water and milk. But the insect is certainly one of the principal agents concerned ; and as for dysentery and other such intestinal disorders, it is undoubtedly the chief mischief-maker. In New York City several local epidemics of typhoid have been traced to flies ; and figures of deaths and of fly multiplication, reduced to mathematical curves, have shown that these infectious bowel complaints, which cause so great an annual slaughter of young children, increase and diminish exactly with the augmentation and falling-off of the number of flies.

In order to make the experiment as fair as possible, the flies wanted for bacteriological examination were caught in cages in various parts of New York—on the water front, in the slum districts, on Fifth Avenue uptown, and elsewhere. One was captured on South Street, which on inspection was found to be carrying in his mouth and on his legs over 100,000 fecal microbes. He had been walking over filth on the water-front, and was on his way to the nearest milk-pitcher. Similar studies, by the way, were made last summer in the City of Washington, including “intensive” observations of both flies and diseases in a district comprising eight squares. The results are not yet quite ready for publication.

One of the diseases spread by the house-fly is Asiatic cholera—a fact discovered as long ago as 1849, when there was an epidemic of that dreaded malady at Malta. A warship of the British Mediterranean Squadron, the . Superb, was cruising for six months during that period, with cholera on board most of the time. On leaving Malta and putting to sea. the flies which had swarmed on the vessel gradually disappeared, and the scourge slowly left her. But later on, when she entered the harbor of Malta again, though without communication with the shore, the flies returned in force, and the colera likewise. Since that date cholera germs have been found repeatedly in fly-specks in cholera wards in hospitals.

Dr. George M. Kober, of Washington, a recognized authority, says that allowing for time lost by sickness, expense for medical treatment, etc., typhoid alone, for which the fly is so largely responsible, costs the people of the l nitcd States $350,000.000 annually.

Notwithstanding these facts, the insect is encouraged to breed unrestricted everywhere. It is allowed to enter freely the houses of most of our people. It is permitted to spread germs over food supplies in our markets, in our kitchens, and in our dining-rooms; while in public restaurants the patron is compelled literally to tight for his meal with swarms of the parasitic creatures, alert, persistent, and unterrified.

Why endure it? if it were difficult to get rid of the house-fly, a general failure on the part of communities to make any efitort to reduce its numbers might properly be termed criminal neglect. But, inasmuch as it is an easy matter to put a stop to the plague for good and all, there is no excuse. That it continues to exist is attributable to a combination of ignorance and carelessness which is a disgrace to our civilization. Flies signify public and widespread pollution. They signify not merely discomfort, but the wholesale distribution of disease and death. Is it not full time, then, that the people should rise up and exterminate the cause of such mischiefs ?

In order to make clear the easy means whereby the hou^e-fly may be exterminated, it is first necessary to explain in a few -words its method of reproduction. The female always lays her eggs in accumulations of filth of somekind—whence it follows that, if filth were not allowed to accumulate, there would be no more flies. But the particular kind of filth most sought for the purpose is horse manure. It is reckoned that ninety-five per cent, of all the flies in our cities are propagated in stables where horses are kept. Every such stable is a fly hatchery ; and a single stable will turn out enoug'h flies continuously during the summer to supply an entire neighborhood.

The female lays her eggs in a closely-packed clump either in or upon the manure or other filth material. Usually she deposits about 120 of them in a batch. They are of an elongated almond shape, pearly white and highly polished. With the microscope they are seen to be finely sculptured with delicate hexagonal markings. Under favorable circumstances they will hatch in ten or twelve hours. It is possible that a female fly may lay more than one batch of eggs during her life, but this is a question not yet satisfactorily settled.

Erom each egg is hatched a footless maggot, which feeds unon the decomposing vegetable matter to be found in the manure or other material by which it is surrounded. In stable manure the eggs may often be dug out in masses numbering many thousands, from a few inches below the surface. At the end of a week or less the maggots are transformed into chrysalids, which, at first of a pale yellowish color, rapidly change to bright red and finally to a dark chestnut hue. Another week, or less, passes by, and then the perfect flies break their way out of the chrysalids and take wing. They pair promptly; the females lay fresh batches of eggs, and another generation is started. The whole cycle, from egg to perfect insect, under favorable circumstances, is accomplished in from ten days to a fortnight.

The insects will breed in fermenting vegetable or animal material of almost any kind. Garbage suits them first-rate. The maggots and chrysalids have been found in great numbers in rotten straw mattresses, among old cotton garments, and even in waste paper that had been exposed to wet. But the fly crop is derived mainly from the source already mentioned.

Now, so far as stables are concerned, which are accountable for ninety-five per cent of the fly output in cities, the hatching of the insects can be absolutely prevented by the simple device of putting all manure into a covered receptacle, and removing the contents once a week. This receptacle should be a water-tight bin or pit, provided with a cover, so as to prevent the ingress and egress of flies.

The additional methods demanded are the following: Abolish all unsanitary outhouses. Allow no accumulations of filth of any kind. Compel people to put all their garbage in covered cans, and remove the contents at least once a week. Compel owners of abattoirs to keep all refuse in covered receptacles ; and remove such waste at least once a week.

If these simple measures were enforced in any community, the housefly would soon become a rare species of insect in that locality. All that is needed in order to achieve this end is an adequate system of inspection, especially with regard to stables, and the enforcement of a suitable penalty in cases of failure to obey the ordinance. Nobody could seriously object, inasmuch as not much trouble and no expense worth mentioning would be involved.

As Dr. L. O. Howard, the Government entomologist-in-chief, says: “It is the duty of every individual to guard against flies on his premises. It is the duty of every community, through its board of health, to spend money in warfare against this enemy of mankind. The duty is as clear as if the community were attacked bybands of ravenous wolves. That the ty-phoid fly—a creature born in filth, and literallyswarming with disease germs—should practically be invited to multiply unchecked, even in great centres of population, is nothing less than criminal.”

The health authorities of New York City estimate that the anti-fly work, when properly carried out, will reduce the typhoid deaths in the metropolis from 650 to about 360 a year, and diarrhoeal deaths from 7,000 to about 2,000. This saving of more than 5,000 lives per annum will be accompanied by an additional saving of 50,000 cases of serious sickness.

An objectionable characteristic of the house-fly which has not been mentioned is that it is strongly attracted by any moist sore on the body of a human being or animal. During the civil war there was an appalling mortality on both sides from what was called “hospital gangrene”—a maladynow known to owe its distribution mainly to flies. Unfortunately, the germ theory of disease was as yet undeveloped, and medical science knew no means of fighting the dreaded compalint. Nothing is easier than for a fly to alight upon an erysipelas sore, and carrygerms from it to a healthy wound on another person—the usual result in such a case being the development of “traumatic erysipelas,” which is an extremely dangerous and frequently fatal disorder.

One fact that ought to be very distinctlyunderstood is that the filth carried by a fly on his legs, though quite sufficient to do plentyof mischief, is inconsiderable in quantitycompared with what he conveys from place to place in his intestinal canal, depositing ii wherever he happens to alight. So constant is this process of deposition that, as ascertained by careful observation, five minutes rarelyelapse without the making, by anyindividual fly-, of at least one flyspeck. If people realized that this was continually going on while flies crawled over their food, they might better appreciate the importance of preventing it.

A painstaking study of the subject byDr. N. A. Cobb, of the Department of Agriculture, has shown that the number of germs of all kinds passed in this way through the bodyof the fly, and deposited bypreference on our walls, picture-frames, chandeliers, furniture, and, worst of all, food-stuffs, exceeds byat least i.ooo times the number carried on the legs. This fact has been ascertained by actual count. Furthermore, by a curious paradox, the house-fly is, after its own fashion, very cleanly-. It is constantly engaged in washing itself, and the filth on its legs it cleans off. as anybodymay easilynotice, if he will but watch the process, by drawing them through its mouth, thus transferring the virulent germs to its stomach.

Typhoid fever, dysentery, cholera morbus, tuberculosis, Asiatic cholera, and certain infectious eye diseases are among the maladies already known to be distributed by the house-fly. But in all likelihood it carries the germs of a good many other complaints. Bv occupation a parasite on man, living at his expense, and depending upon him to a great extent for protection, this abominable insect returns the obligation by afflicting upon its benefactor suffering and death in a great variety of forms.

It is a remarkably intelligent insect. Erom birth it seems to be perfectly well aware that man is its enemy, but apparently regards him with contempt as a sluggish and crawling creature of inferior activity and resource. Its sight is very acute, each of its two huge eyes being literally several thousand eyes in one ; and for each of these myriad eyes it is provided with a separate lens and retina—though, of course, all of them furnish to the brain of the fly a single image, just as our own two eyes see only one object. In addition, it is able to think and act upon its thought in a small fraction of the time which the smartest man requires to go through the same processes.

The fly’s cunning is doubtless a matter of inherited experience. Unlike ourselves, the insect is born wise. It sees not very much of the world during its lifetime, for it rarely travels more than a few rods away from the place where it was originally hatched. The widespread popular notion that it bites on occasions is wholly erroneous. It has no mouth-parts for biting. Occasionally stable flies, of entirely different species, find their way into dwelling-houses and bite people— whence the mistake. Another wrong idea is that it walks on the ceiling by the help of sucking discs attached to its feet—the fact being that each of its six paws is provided with a pair of cushions and two hooks. The cushions are provided with minute hairs, which are kept moist by a secretion, causing them to adhere to a smooth surface.

Like other insects, the house-fly has enemies, one of which is the familiar household myriapod, commonly known as a “centipede.” But the most effective foe of the fly is a peculiar fungus disease. One sometimes sees a specimen of Musca domestica fastened to a window-pane by the whitish threads of this fatal fungus. But, in spite of all hostile influences-—even cold, which wipes out the great majority in the winter time —a sufficient number of flies, in cool latitudes, always find shelter, mostly in dwelling-houses, to start a fresh generation in the following spring.

It does seem wonderful, when one comes to think of it, that so small and contemptible an insect should be able to do such an immense deal of harm to mankind. But it is much more astonishing that we, now that we have come to understand the dangerous character of this hitherto-despised adversary, should not only permit, but encourage it to breed among us—actually, as it might be said, establishing and maintaining hatcheries, in the shape of stables, for its artificial propagation. Surely, however, this state of affairs cannot much longer continue. Ignorance no longer furnishes an excuse. Action must be taken for the extermination of this insect enemy. In fact, it has already been begun. And there is every reason to believe that eventually the adoption of proper measures, such as those above suggested, will result, in the practical extirpation of the winged ueril in our communities and free us from some of the ills that beset us.

“ENTHUSIASM breakfasts on obstacles—lunches on objections—dines on competitors and rests in peaceful slumber on their scattered tail feathers.” A. E. Landon