PREVENTIVE MEASURES 
193 
constructed, and horse manure infested with larvae 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 manure 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 
afford 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 
