THE HOUSE FLY DISEASE CARRIER 



at farm yards, where they remain until the morning sun 

 tempts them out. 



Both males and females suck blood. According to 

 Osborn, while this fly inflicts a deep bite it does not 

 gorge itself at a single animal, but may fly from one 

 to another in securing a meal. From this fact he thinks 

 the idea that this fly is apt to be a transmitter of glan- 

 ders from diseased to healthy horses, and anthrax 

 among cattle, receives important support. The punc- 

 ture under ordinary circumstances does not seem to be 

 poisonous to men, and aside from the pain given it is 

 less dangerous than a mosquito bite. Newstead no- 

 ticed a female drive its proboscis into the thorax of a 

 dead companion and apparently suck up the juices of 

 its body. The same writer permitted one to suck blood 

 from his hand and observed it carefully during the 

 process. The insect sat high on its legs, the whole of 

 the proboscis was straightened and held vertically, and 

 the lower third was driven into the flesh. During the 

 process, which lasted fifteen minutes, the proboscis was 

 constantly but somewhat slowly moved up and down, 

 and also with an occasional semi-rotary movement, like 

 the action of a quarryman's hand drill. There was no 

 subsequent irritation or soreness of any kind. The 

 fly died twelve hours after feeding. During other ob- 

 servations Newstead found that the flies lived for sev- 

 eral days in captivity, and that the females died either 

 immediately or shortly after laying their eggs. 



The biting house fly has almost as wide a geographic 

 distribution as the true house fly. It was probably orig- 



