RESEARCH REQUIRED 39 



possible to understand how many cases of human 

 affections any single fly can be responsible for. Such 

 an exact knowledge would influence our methods of 

 dealing with the pest, would determine the necessity 

 of instituting measures against the living flying insects 

 during epidemics of typhoid or infantile diarrhoea. At 

 present, during heat-waves in England, the house-fly 

 is believed to live for three weeks only, and by the 

 time the epidemic has appeared single infected insects 

 can have but little time to live, if the short-life theory 

 is correct. So that, with our existing information, 

 measures of fumigation and imago killing seem hardly 

 necessary even if we could be certain of destroying the 

 actual offenders. The destruction of larvae is much 

 easier and seems more promising so far as the prevention 

 of fly-borne disease is concerned. But with patient 

 research much more might be known about these 

 dangerous insects than is the case at present. With 

 the institution of fly-reduction generally more wide- 

 spread interest may result in more knowledge and then 

 perhaps these problems will become problems no 

 longer. 



