120 INSECTS AND MAN 



(1666) remarked that if swarms of insects, especially 

 house flies, were abundant in summer, the succeeding 

 autumn was unhealthy. A number of authors, e.g. 

 Crawford (1808), might be cited who refer in a general 

 way to insects, especially to house flies, as carriers of 

 infection. Moore (1853) refers to flies as possible carriers 

 of cholera, typhoid, tuberculosis, anthrax, and leprosy ; 

 Leidy (1872) refers to flies as carriers of the infection of 

 hospital gangrene and of wound infection, . . . but none of 

 these authors do more than offer surmises regarding the 

 part played by flies in the spread of disease." 



To avoid any misunderstanding as to the part played 

 by house flies in the transmission of disease, we may state 

 at once that their work is purely mechanical, though none 

 the less deadly on that account. Their mouths are not 

 adapted for biting, and they are quite unable to pierce the 

 human skin, or any skin for that matter, if they would. 

 " They are a disgusting pest which feed and wallow in filth 

 of all sorts, and when their proboscides and legs are covered 

 with germs which are growing and living in such filth, 

 they proceed to our food and to the food of our children 

 and contaminate it. This infected food we human beings 

 eat and drink, and in this way disease is kept circulating 

 from one person to another in a never-ending cycle, the 

 flies carrying disease from one sick person to the food of 

 others and perhaps to and from animals besides." In time 

 of war the house fly has proved more deadly than the 

 enemies' bullets. During the Spanish-American war more 

 than eighty per cent, of the deaths were due to typhoid ; 

 during the Boer war the number of deaths brought about 

 by the agency of the house fly are impossible to compute. 



The disgusting habits of these insects have been 

 mentioned in another place, how they swarm on all 

 manner of filth and garbage and fly direct therefrom to 

 our food and persons, which they soil with their excrement 

 and vomit, in addition to carrying oddments of the 



