288 THE POPULAR SCIENCE MONTHLY 



milk by flies is a common occurrence. Hundreds of bacteria have been 

 counted on the feet of flies caught in the cow stables. 



Some sanitarians believe that many infant lives would be saved if the 

 fly could be kept away from the baby's milk. A recent investigation in 

 New York City carried out by Dr. Donald B. Armstrong (published in 

 the Journal of the American Medical Association, January 17, 1914,) 

 seems to show that there is some connection between flies and infant mor- 

 tality. The author's results seem to indicate that the fly is a much ne- 

 glected factor in the etiology and transmission of summer diarrhea. He 

 thinks that greater attention should be given to the elimination of the 

 insect by all those interested in prevention of infant mortality. Two 

 areas were covered by his investigations, both practically alike in popula- 

 tion and other conditions. The first area was subjected to every possible 

 precaution against flies. The means were educational campaign, exhibi- 

 tion of picture films of flies in a nearby theater, screening of the 1,700 

 doors and windows, and placing of large fly traps in the courtways, yards 

 and stables. The second area was permitted to pursue its usual insani- 

 tary course. In the protected area the total days of sickness of diarrheal 

 diseases among infants was 273, in the unprotected area 984. 



According to Farmer's Bulletin 540, U. S. Department of Agricul- 

 ture, the stable fly, also known as the wild fly, the straw fly and the biting 

 house fly, commonly breeds in horse manure, especially if straw is pres- 

 ent, as is usually the case. It has been believed, although lacking con- 

 firmation, that infantile paralysis and pellagra are communicated by 

 this species. It has been more definitely demonstrated that this fly is 

 instrumental in spreading some diseases of domestic animals. Aside 

 from these facts it is a tormentor of live stock. Horses and cattle suffer 

 more than other animals, but sheep, goats, hogs, dogs and cats are known 

 to be infected by these flies. Even man is not immune. A tropical dis- 

 ease of camels, horses and cattle, known as " surra," is communicated by 

 this fly. Anthrax, glanders and possibly other diseases of cattle, also 

 communicable to man, may be transmitted by the stable fly. Although 

 the chief breeding places are straw stacks, the manure piles commonly 

 found near stables where horses are kept furnish suitable breeding places. 

 Adult flies may follow for considerable distances traversing roads and, 

 when engorged with blood, settle on nearby objects. Other teams pass- 

 ing along the same highways are subsequently attacked. It is evident 

 that with the reduction of horses and horse stables this pest will be 

 greatly reduced. 



Flies do not generally act as intermediate hosts in the transmission 

 of disease. Usually they carry the germs on their feet or in the intestinal 

 tract and infect food by walking over it or dropping on it. The danger 

 from flies is greater than from mosquitoes. The latter act as intermedi- 

 ate hosts and carry the virus of malaria, yellow fever and other diseases. 



