DESTRUCTION OF MOSQUITOES, ETC. 671 



come to the conclusion that the best and most rational means to 

 prevent this pest is the observance of cleanliness, both inside and 

 outside all places of habitation. The prompt removal and crema- 

 tion of all organic refuse from kitchens, together with the regular 

 removal, more especially of stable manure, their favourite breeding 

 habitat, would greatly mitigate the fly nuisance in the summer 

 months. 



Experiments we carried out in 1908 in Auckland, N.Z., on the 

 breeding habits of flies by placing pieces of meat, which had been 

 exposed to flies, in fine meshed cages, showed that although maggots 

 prefer earth as a congenial media for the larval or pupal stage of 

 development, still it is possible whenever the temperature reaches 

 60°F. actually to breed flies in the meat itself, which ultimately 

 has the appearance of being honeycombed. Although it has been 

 shown that flies as carriers of typhoid more especially may transfer 

 pathogenic germs on their feet, mandibles, and other parts of their 

 bodies, yet it is now recognised that the chief danger from flies is 

 due to their method of feeding. The fly defaecates on an average 

 twice a clay, but as Dr. Grahame, in a report to the L.G.B., England, 

 shows, it vomits much more frequently. Before taking food, of 

 which it can imbibe sufficient in a few seconds to last almost as 

 many days, it exudes a fluid, dissolves the food, and then fills its 

 crop or stomach. It is in this way that food becomes infected by 

 flies which have had access to typhoid stools or tubercular sputum, 

 the organisms having actually been recovered from the faeces and 

 stomach witliin two to seven days after contact. 



As a matter of fact, the fly is really cleanly in its person, because 

 it has to be clean, and to remove at once foreign matter from its 

 body, as otherwise the breeding apertures in its body become 

 clogged and it dies. Often the cleaning of the fly's body is at our 

 expense, as also is its method of walking with filthy feet over food 

 after feeding on faeces. The ease with which its breathing mecha- 

 nism is deranged, however, is illustrated by the almost in- 

 stantaneous effect of the slightest film of kerosene applied to the 

 fly's body, an effect resulting perhaps as much from the closing of 

 the pores of the skin to the escape of the vitiated air, as to the closing 

 of the breathing tubes to inspiration. 



In 1908 my attention was drawn to a plague of flies which 

 congregated so thickly on the Rangitoto wharf, Auckland, as to 

 make the lower surface of the structure black. Advantage was 

 taken of a visit of some Parliamentarians to Motuihi to demonstrate 

 the effects of kerosene as a fly exterminator. Inspector Grieve, of 

 the Health Department, spent an hour syringing the wharf with 

 kerosene. The bottom of the boat from which he operated was 

 over an inch deep with dead flies, and except in places where the 

 kerosene had not reached, the liies disappeared. Last year by 

 invitation I attempted the wholesale destruction of flies at the 

 saleyards at Otahuhu. First we tried fumigation with formalin 

 of the kitchen attached to the restaurant, and after two hours 

 found that fumigation had practically no effect. We certainly 



