DIPTERA OF MINNESOTA. 



147 



studied in this connection, thirty-six were found to breed in human 

 faeces, while the remaining forty-one were captured on such ex- 

 crement. It should be said in connection with the facts cited regard- 

 ing typhoid epidemics in our southern camps during the Spanish 

 war, that Surgeon General Sternberg was thoroughly alive to this 

 danger, and issued directions covering this point, but these direc- 

 tions were not regarded. Flies have been carried by railway cars 

 and other conveyances into districts where they were not previously 

 present. The writer, when in Oregon, was told by some one of the 

 old settlers, that before the advent of the railway in Western Oregon 

 house flies were unknown there. 



Fig. 142. A petri dish containing agar, over wliicli we allowed a house fly to crawl. The 

 white spots are colonies of bacteria started by germs on the feet of the fly. 

 Original; courtesy of Mr. Beebe of the Veterinary Department. 



THE STABLE FLY. 

 Stoinoxys calcitrans, Linn. 



Resembling the house fly so closely in general appearance as 

 to be classified as such by the ordinary observer, until what he re- 

 gards as a "house fly" pierces his skin, causing for an instant a sharp 

 pain. This common mistake is enhanced by the fact that the stable 



