254 CONTROL OF FLIES 



until it can be removed. This should be done at least once a 

 week, since under suitable conditions the larvae reach full growth 

 in about five days, and many of them wander to loose debris in 

 the neighbourhood to pupate. 



The possibility of flies breeding from manure spread over 

 land is another important and practical point on which Howard 

 (191 1, p. 192) quotes some of Hine's unpublished observations. 

 The latter found that flies came out in abundance from spread 

 manure infested with larvae, but that only one generation 

 appeared, and that the spreading prevented the development of 

 future generations in the same manure. 



An example of the nuisance which may be created in the 

 neighbourhood of large accumulations of rubbish has already 

 been quoted (p. 75). 



Masses of decaying vegetable refuse should not be tolerated, 

 and it should be remembered that numerous flies are bred from 

 badly kept rabbit hutches, etc. 



Receptacles containing kitchen refuse should be kept closed 

 to prevent flies laying their eggs in them. As previously pointed 

 out, flies which happen to enter them, may be caught by 

 employing suitable methods. 



Newstead (1908) has pointed out that ash-pits may be so 

 screened as to prevent the breeding of house-flies in them. 



Earth closets and privies, which are not very carefully looked 

 after, are prolific breeding places of flies. In towns they ought 

 to be abolished, as far as possible, but where they must be 

 retained they should be of the best type. Stiles (1910) has given 

 much attention to this subject, and has published detailed 

 instructions for building really sanitary privies, which are fly- 

 proof, well ventilated, and have suitable receptacles, containing 

 the necessary amount of water with a film of kerosene floating- 

 on it. The use of kerosene in privies, wherever possible, is to be 

 strongly recommended, since it kills not only the eggs of parasitic 

 intestinal worms, but fly larvae of all kinds. 



Permanent preventive measures, even though a staff of 

 inspectors has to be employed, will always be less expensive in 

 the end, and also very much more effective than the use of 

 temporary methods in the form of insecticides, which must be 



