44 



Insects and Disease 



fly, breeze-fly, etc. They are very serious pests of 

 horses and cattle, sometimes also attacking man. 

 Their strong, sharp, piercing stylets enable them to 

 pierce through the toughest skin of animals and 

 through the thin clothing of man. The bite is very 

 severe and irritating, and as the flies sometimes 

 occur in great numbers the annoyance that they 

 cause is often very great indeed. It has often been 

 claimed that these flies as well as the stable-fly and 

 others carry the anthrax bacillus on their proboscis 

 from one animal to another, and although this may 

 not have been definitely proven the evidence is 

 strong enough to make a very good case against the 

 accused. It is interesting to note in this connection 

 that anthrax, a very common disease among the 

 domestic animals and one which may attack man 

 also, was the first disease to be shown to be of 

 bacterial origin. It was only about thirty-five 

 years ago that the investigations of Koch and 

 Pasteur demonstrated that the presence of this 

 particular germ (Bacillus anthracis) was the cause 

 of the disease, and it was early recognized that such 

 biting flies may be important factors in the spread 

 of the disease. 



The stable-fly (Fig. 23) (Stomoxys calcitrans) 

 which looks very much like the house-fly and, as 

 will be noted later, frequently enters houses, is 



