INSECTS AND DISEASE 



381 



enteritis and other intestinal diseases occur during fly time, and 

 a moment's thought, in the light of our knowledge of the habits 

 of flies, will show how easy it is for the milk to become infected 

 around dairy barns or milk wagons where the flies are always 

 found in great numbers. It is quite possible, too, that flies 

 may sometimes be concerned in the transmission of the germs 



FIG. 169. Larvas and pupa; of house-fly, Musca domcstica, in manure. 



(Natural size.) 



that cause tuberculosis, influenza and other dreaded diseases. 

 Of course only a small proportion of the flies carry disease 

 germs, but they are all filthy, and it is impossible, without 

 careful laboratory analysis, to distinguish those which carry 

 disease from those which are merely dirty. 



The only safe thing to do is to banish them all, not only from 

 the house and the market place, but from the storerooms and 

 dairies and all other places where food of any kind may be 



