CONTROL OF FLIES 253 



mans enemies — a veritable wolf in sheep's clothing. There is no 

 virtue in the house-fly ; there is no reason why it should continue 

 to exist, and its death knell is being sounded wherever com- 

 munities care for the health of the individual. Dr E. P. Felt 

 (1909) has said 'our descendants of another century will stand 

 in amazement at our blind toleration of such a menace to life 

 and happiness'" (Hermes, 191 1, p. 533). 



The methods employed in removing breeding places, or in 

 rendering them unsuitable for the larvae by chemical agents, or 

 in preventing the deposition of eggs by mechanical means, must 

 differ to some extent under the different conditions prevailing in 

 various localities, but all must depend on an accurate knowledge 

 of the habits of flies and their larvae. 



In this chapter it is not proposed to give specific and detailed 

 instructions as to the methods which should be employed in each 

 instance, but only to point out the main sources of flies. 



Wherever a nuisance from flies prevails their breeding places 

 must be searched for, and it should be remembered that numbers 

 of flies may be bred from relatively small accumulatious of filth, 

 such as human excrement. In cities, however, the majority are 

 probably bred from horse manure, though many of the larvae 

 live in the excreta of other animals, in ash-pits and in decaying 

 vegetable matter. Search must therefore be made for accumula- 

 tions of refuse. Fortunately to produce the requisite degree of 

 fermentation for rapid breeding, quantities of most of the suitable 

 materials, sufficient in amount to be readily noticeable, have to 

 be accumulated, and the search for the breeding places of the 

 bulk of the flies of a given neighbourhood need not be a very 

 close one. At the same time no accumulations of rubbish of any 

 kind ought to be ignored, since even rags and paper under 

 proper conditions of moisture and temperature may afford 

 breeding places. 



The open manure heap ought to be abolished, and stables 

 kept clean. House-flies breed in large numbers in the cracks of 

 the stable and stall floors, where manure falls into them, and 

 consequently floors with cracks ought not to be permitted. 

 Receptacles may be constructed with tightly fitting lids, pre- 

 ferably in dark corners, where the stable refuse may be kept, 



