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By R.C. ROBERTSON, M.D., D.P.H., and Stephen M.K. Hu, M.S., SC.D. with illustrations by R. V. Dent, F.R.P.S. (Henry Lester Institute of Medical Research, Shanghai) 
WITH THOUSANDS of refugees massed in our city and cholera raging in our midst,
Shanghailanders have gone fly-conscious these hectic days. The congested conditions incidental to hostilities around our city have resulted in a bigger crop of flies this summer and autumn than ever.
To satisfy the many enquiries concerning the present fly menace, we are making an attempt here to summarize for our local public the gist of the situation. There is a vast literature on flies: scientific works, health bulletins and pamphlets of a public health nature abound. We have here attempted to give in concise form for the general reader the main facts regarding the subject with special reference to the situation in war stricken Shanghai. We have made free use of a number of books and recommend for more detailed and technical information the works mentioned in the list of appended references. We also refer the reader to pamphlets issued by the Municipal authorities in Shanghai as well as those of the National Health Administration of Nanking.
It has been only in comparatively recent times that the facts have been fully established and the importance of the ro1e played by flies in the transmission of disease been realised.
Within the memory of the fathers of the present generation the fly was classed without question among the friends of man. A poetic enthusiast of the past actually perpetrated
the line, "A dipterous angel dancing light attendance upon Hygeia."...
Shanghai is having plenty of its share of the "infinite torment of flies" at the moment. We have every reason to believe that the cholera epidemic, which has taken a considerable toll of the city's population and has been one of our chief epidemiological problems in the first months of the war, has been largely fly borne. No doubt some of the first cases were due to drinking polluted water, but case to case infection has been due to flies and the city's congestion with war refugees.
Most of the organised refugee camps have been supplied with Shanghai Water Works water, which is above suspicion, yet a certain proportion of cholera cases have occurred among refugees situated in buildings where there has been an inevitable break down in sanitary conditions.
During the hostilities there has been an immense amount of decaying animal matter of the nature of human and animal corpses lying exposed without burial. This has caused an abnormal fly situation.
It would seem appropriate here to describe briefly some of Shanghai's flies, since they undoubtedly play an important role in the causation of what we locally term summer diseases, namely, cholera, typhoid fever and dysentery.
The various flies must have been observed by almost every Shanghai resident armed with a swatter during these critical days. Our natural petulance at war conditions and aerial bombing has taken a common expression in animosity against our insect aerial foes.
The flies enumerated in this paper are not difficult to collect, and at the moment any interested and vindictive Shanghai resident should be able to complete the collection on a Sunday afternoon without going far afield.
The fly has no friends; it has many enemies. Its eggs are frequently eaten by fowls. The poultry which stalk about the farmyard feed gladly on flymaggots. It would be very disappointing for the parent fly to realise, if it could, that its offspring, instead of spreading disease among human beings, had merely become food for fowls. It would be an ambition blunted in its realisation.
The ideal method of fighting flies is, of course, to destroy the eggs and maggots. But this is not so easy, as the opportunities for flies to breed are so numerous, especially in a metropolis such as this, in China, where waste material in the form of decaying animal and vegetable matter appears to be an invariable accompaniment of life.
One must do what one can in protecting oneself against those flies that have happened to escape destruction from anti-maggot measures. Where the elimination of the pest is practically impossible, the first thing to be considered are methods of protecting food and drink from contamination. The most direct of these methods is the thorough screening of doors and windows to prevent the entrance of flies. But they get in, one way or another, so we are faced with the problem of those that manage somehow to gain admittance.
Indulging in the indoor sport of swatting flies may give some satisfaction, but we must take the precaution of not landing them on our foods while we are at it. The slogan, "Swat that fly," has been taken too literally in some places. Besides, the advocating of "fly swatting" on a big scale only serves to attract the attention away from the real issue, namely, the control of breeding places. Interest should be won over to the side of civic cleanliness, and the slogan will have to be changed from "swat that fly" to "swat that manure pile."
Sticky fly papers may be more of a nuisance than anything else, but, if properly handled, serve a good purpose. House flies are very fond of gathering on a string or strip of paper hanging from the ceiling. This may be taken advantage of in a very effective manner by suspending narrow strips of sticky fly paper from the ceiling. 
Finally we must admit that all methods of killing the flying insect are unsatisfactory. When all are convinced that the fly is a creature of disgusting and dangerous habits, no more to be tolerated inside our dwellings and provision shops or upon our meal tables than a plague-stricken rat, then we may expect the kind of cooperation with the health authorities which will render community action effective in suppressing this pest at its very sources.
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