76 REVIEW — TnOPIOAL MEDICINE, ETC. 



Flies— A very excellent paper on House-Flies is that by Howard.' He deals with all the flies 



conlinufd which invado houses in the United States, mentioning Mnsca domestica, Stomoxys calcitrans, 



Pollenia rudis (the cluster fly), Muscina stahnlans, a stable fly exactly like the common 



house-fly, and throe species of so-called blue-bottle fly, namely, GalUplwra erythrocephala, 



the blow-fly, the small blue-bottlo fly, Phormia temenovie, and the green Lncilia ciesar. 



Hoinalomyia canicidaris and Homalomi/ia brevis also receive attention, as does the small, 

 jet-black window fly, Scenopinus fenestralis, which breeds in the dust under carpets. The 

 small and slender Sepsis violacea, often seen on window-panes, is also mentioned and figured. 

 The chief natural enemies of the house-fly are detailed. These are the house centipede, 

 a small reddish mite and, in its larval stage, hymenopterous parasites and predatory beetles. 

 EmpHsiiia mnscxi, however, a form of fungus, is its principal destroyer, but its action is more 

 than counterbalanced by the rapidity of development of the fly. 



Eemedial and preventive measures as regards the breeding of house-flies are considered. 

 Stable manure is their special breeding-place, and experiments were tried with various 

 substances. It was found that by spraying eight quarts of fresh horse manure with one 

 pint of kerosene and afterwards washing down with one quart of water the manure was 

 thoroughly rid of living maggots. While good results were obtained on a small scale, this 

 method employed on an economical basis proved inadequate wlien applied to large quantities 

 of manure. Chloride of lime also failed on a large scale and the best results were obtained 

 by the preparation of a special receptacle for manure. A chamber 6 feet by 8 feet was 

 constructed with a door opening into the stable, and a window with a wire screen. In the 

 outside wall of this building another door was placed. All manure was thrown into this 

 chamber and each morning a shovelful of chloride of lime was scattered over the fresh layer. 

 After ten days or two weeks the manure was removed via the outside door. 



House-flies also breed in human excrement and, as recently discovered, in cow-dung. 

 Howard mentions a French method for keeping them away from privies and cesspools. 

 Residuum oil is used, two litres per superficial metre of the pit. This is mixed with water, 

 stirred with a stick, and thrown into the receptacle. Not only does this kill larvte and 

 prevent the entrance of flies, but it practically turns the cesspool into an anaerobic tank. 



Finally, Howard quotes certain U. S. regulations which might well be adopted with 



appropriate modifications in all towns : — 



All stalls in which animals are kept shall have the surface of the ground covered with a water-tight 

 floor. Every person occupying a building where domestic animals are kept shall maintain, in connection 

 therewith, a bin or pit for the reception of manure, and, pending the removal from the premises of the manure 

 from the animal or animals, shall place such manure in said bin or pit. This bin shall be so constructed as to 

 exclude rain-water, and shall in other respects be water-tight, except as it may be connected with the public sewer. 

 It shall be provided with a suitable cover and constructed so as to prevent the ingress and egress of flies. No 

 person owning a stable shall keep any manure or permit any manure to be kept in or upon any portion of the 

 premises other than the bin or pit described, nor shall he allow any such bin or pit to be over-filled or needlessly 

 uncovered. Horse manure may be kept tightly rammed into well-covered barrels for the purpose of removal in 

 such barrels. Every person keeping manure in any of the more densely populated parts of the district shall cause 

 all such manure to be removed from the premises at least twice every week between June 1st and October Slst 

 and at least once every week between November 1st and May 31st of the following year. No person shall remove 

 or transport any manure over any public highway in any of the more densely populated parts of the district 

 except in a tight vehicle which, if not enclosed, must be effectually covered with canvas, so as to prevent the 

 manure from being dropped. No person shall deposit manure removed from the bins or pits within any of the 

 more densely populated parts of the district without a permit from the health officer. Any person violating any 

 of the provisions shall, upon conviction thereof, be punished by a fine of not more than 40 dollars for each offence. 



Fresh proof of flies as carriers of infection is furnished by the work of Buchanan^ with 

 M. domestica and the blue-bottle fly M. vumitoria. He describes the form and structure of 

 the fly's tarsus and shows how well adapted it is for carrying a large amount of infective 

 material. He had positive results as regards transference of specific germs and growth on 

 media, with swine fever, staphylococcal abscess, pulmonary tuberculosis and aiithrax. It 

 was less easy to prove conveyance of infection in the case of enteric fever, but this also was 

 successfully accomplished, the culture medium employed being that of MacConkey as 

 modified by Griinbaum and Hume. 



Another useful paper is that by Hewitt. ' He believes that Homalomyia canicularis is 

 quite as guilty as M. domestica in the dissemination of infectious disease. He notes that in 



' Howard, L. O. (September 21st, 1906), United States Dept. of Agriculture, Bureau of Entomology Cir., 

 No. 71. Kevised Edition. 



^ Buchanan, R. M. (.July 27th, 1907), "The Carriage of Infection by Flies." Lancet, p. 216, Vol. II. 



" Hewitt, C. Q. (December 11th, 1907), " On the Bionomics of certain Calyptrate Muscidse and their Economic 

 Significance, with Especial Reference to Plies Inhabiting Houses." Journal of Economic Biology, p. 79, Vol. II. 



