42 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 2 



of the two parties inentioued above and a change in the method of 

 disposing of typhoid discharges. 



The evidence against this insect may, therefore, be summed up 

 briefly as follows: Virulent typhoid bacilli have been found upon the 

 legs and within the bodies of this insect, persisting in the latter case 

 for 23 days. A number of serious outbreaks have been observed 

 by competent physicians, where infection through a common water 

 or food supply did not satisfactorily explain the trouble. This pos- 

 itive evidence, while not establishing beyond all question the culpa- 

 bility of the fly, is further supported by the opinion of a number of 

 reputable physicians who have had extensive experience with out- 

 breaks of this character. 



The evidence showing that flies may play an important part in the 

 diifusion of cholera is, according to Dr. Nuttall, absolutely convinc- 

 ing. He cites experiments showing that cholera bacilli may be found 

 on flies in large numbers, while they may occur in the dejecta within 

 17 hours after feeding and as late as four days. Infected flies have 

 been given access to milk and cholera cultures made therefrom. 



Tj^phoid fever and cholera, while both serious infections, are by no 

 means the only diseases which may be conveyed by flies. Certain 

 forms of diarrhcea and enteritis are undoubtedly due to specific 

 germs, and there is no reason why the bacilli causing these infections 

 may not be carried as easily and in the same way as those responsible 

 for typhoid fever. The monthly bulletin of the New York State De- 

 partment of Health for October, 1908, states that during 1907 there 

 were in New York state 37,370 deaths of infants under two years of 

 age, 9,213 being due to diarrhoea and enteritis. Careful investiga- 

 tors, it is stated, have placed the proportion of deaths between bot- 

 tle-fed and breast-fed babies as 25 to 1. Physicians recognize the 

 necessity of providing pure milk for young children, and in most in- 

 stances it is comparatively easy to see how flies might be responsible 

 for the major portion of the infections, since they usually occur in 

 numbers about stables, in the vicinity of milk houses, in the neigh- 

 borhood of milk stations, on milk wagons and, in fact, are found 

 in greater or less numbers wherever milk is stored. Martin states 

 that each succeeding year confirms his observation of 1898 to the ef- 

 fect that the annual epidemic of diarrhoea and typhoid is connected 

 with the appearance of the common house-fly, while Nash in The 

 Lancet, records no mortality from diarrhoea among infants at South- 

 end during July and August, 1902, this immunity being accompanied 

 by the almost complete absence of the house-fly. This insect was 

 abundant in that locality in September and coincidentally epidemic 



