20 THE IMPORTANCE OF DOMESTIC FLIES 



are typhoid carriers, who appear apparently healthy and 

 who have had but mild attacks of the disease. These 

 discoveries produced some small discussion amongst 

 medical men, but there they seem to have ended ; at 

 all events, there has been little organised attempt to 

 carry the matter further, or even to try to reduce the 

 numbers of flies in places where the disease has occurred 

 in epidemic form. The reasoning brought against these 

 discoveries is quite insufficient to stop work on the 

 subject. Because the epidemic died out before the in- 

 fected flies, which had become sleepy and sluggish in 

 the cold, the possibility of the flies being carriers must 

 be denied, they say; and because infected flies were 

 found without the human disease being found, therefore 

 it is supposed that the two have no connection ; and 

 because two artificially made graphic curves of the 

 numbers of flies and cases of disease did not corre- 

 spond, the whole idea was said to be nonsense. But 

 there is no reliable method of counting either flies or 

 mosquitos in towns or districts. It is ridiculous to set 

 aside good work for such petty reasons. We know 

 that it is possible to find an infected mosquito with- 

 out discovering any human malaria, and yellow fever 

 frequently ends with the onset of the cold weather, 

 when some mosquitos persist, though they have become 

 sleepy. Yet every one agrees that mosquitos carry 

 malaria and yellow fever, and that, indeed, these diseases 

 are only carried by these insects. 



At all events, nothing practical and on a large scale 

 seems to have been done to deal with flies in this 

 country, and in consequence, during the summer of 

 1911, which was an exceptionally warm one, house-flies 

 bred in great multitudes, and in the early part of July 

 the children began to sicken and die. In London the 



