PREVENTIVE MEASURES 193 



constructed, and horse manure infested with larvse was 

 spread at the rate of one quart to a square foot. Flies 

 came out in abundance in these cages, although the 

 weather was such that the m.anure and the soil beneath 

 it were very dry during the time the observations were 

 taken. After the flies from the larvae that were in the 

 manure at the time it was spread out all emerged, the 

 cages were kept in place for several weeks, but another 

 generation of flies did not appear, indicating that the 

 careful spreading of manure in the fields in the sum- 

 mer does not cause the death of the pupae and of the 

 majority of the larvae that are in it at the time the 

 spreading is done, but it does, on the other hand, pre- 

 vent the development of future generations in this same 

 manure. 



Thus it often happens that after a lawn has been 

 heavily manured in early summer the occupants of the 

 house will be pestered with flies for a time, but finding 

 no available breeding places these disappear sooner or 

 later. Another generation will not breed in the spread 

 manure. 



In the search for breeding places no accumulations 

 of rubbish of any kind must be ignored. Even old 

 rags and paper under proper moisture conditions will 

 afiford breeding places. All such substances should be 

 removed or destroyed. 



The Treatment of Horse Manure 



Some experiments were tried by the writer in the 

 summer of 1897, with the intention of showing 



