THE HOUSE-FLY 11 



ENEMIES OF THE HOUSE-FLY 



The house-fly has a goodly number of enemies, some 

 of them members of the plant world, but most of them 

 belonging to the animal kingdom. These enemies, how- 

 ever, do not seem to succeed in reducing the num- 

 bers of the house-fly to any great extent. Of course, it is 

 impossible to say how many house-flies there might be if 

 none of its enemies existed. 



It is a common thing to find dead house-flies on window 

 panes in the fall surrounded by a whitish ring. This 

 ring is caused by the minute white spores of a fungus that 

 lived within the body of the fly, finally causing its death. 

 There are, at least, three species of these minute low 

 plants or fungi that have been found to attack the house- 



Certain mites are often found attached to the bodies 

 of house-flies. It is certain that some of these, at least, 

 are simply clinging to the fly as a method of transportation 

 from one place to another. They undoubtedly lie in 

 wait for the fly and when opportunity offers seize hold and 

 are carried to a supply of food, where they drop off. It 

 is possible that other species of these mites feed upon their 

 host, but very little of definite information is at hand con- 

 cerning this point. 



Of course, spiders, when allowed to build their webs 

 and establish themselves in rooms, will catch and kill 

 many flies. 



Hornets are more or less effective fly catchers. The 

 English Entomologist, Westwood, writing in 1840, quotes 

 from St. John's "Letters to an American Farmer " to the 

 effect that "The Americans, aware of their [hornets] 



