February, '19] headlee: sprinkling sewage filter fly 



37 



purification plant from which they come. Whether these flies actually 

 carry infection has never been determined, but the presumption that 

 they do is not at all unreasonable. 



Almost wherever sprinkling sewage filters are maintained these flies 

 are produced and trouble of this kind is likely to occur. 



;%, wx/t 



7^ If 



%/r 



Fig. 3. — Life stages of the Sprinkling Sewage Filter Fly. A, Adult; B, Eggs (After 

 L. Haseman); C, Larva; D, Pupa. 



Life-History and Habits 



The Sprinkling Sewage Filter Fly remains in the filter throughout the 

 entire year, but to what extent breeding takes place in the winter time 

 we are unable to say. Reproduction, however, occurred during the 

 month of December, 1918. 



The eggs are laid on the film. The young hatch and make their 

 way into it. Here they establish themselves with the breathing tube 

 projecting from the film surface and the body buried in it. In this 

 position they feed and grow to maturity'. Transformation to pupjB 

 takes place in the film and the pupa) assume a position with their two 

 breathing tubes sticking through the surface and the rest of their 



