344 VETERINARY HYGIENE 



Manure pits are the most favoured breeding places and horse 

 manure is preferred to cow manure. Cow manure contains too 

 much moisture and the surface becomes caked over, both conditions 

 being adverse to the life of the larvae. Cow manure, if it contains 

 much straw, may be used as a breeding site. Any rubbish lying 

 about a farm or elsewhere affords a suitable breeding place. Any 

 decomposing food material or excreta, that is food material that can 

 be easily ingested by the adult fly and also serve as nutriment for the 

 larvae when they hatch out from the eggs, attracts flies both for 

 immediate nourishment and as suitable spots for the deposition of 

 their ova. Human and animal faeces afford suitable food, so also 

 do milk and other foodstuffs found in houses. 



PREVENTIVE MEASURES. = Protective measures against flies 

 should be directed toward (1) reduction in the number of breeding 

 places, or making such unsuitable; (2) destruction of the adult 

 flies; (3) destruction of eggs and larvae; (4) protection of 

 animals from flies; (5) protection of human food, especially milk, 

 from flies. General cleanliness and tidiness about animal buildings 

 will do much to reduce the number of flies by removing dirt and 

 rubbish. The most productive anti-fly measure is the destruction 

 of eggs and larvae in manure pits. Horse manure appears to be 

 the outstanding breeding place for flies, and this fact may be made 

 good use of. According to Roubaud* the manure must be fresh, 

 not older than 24 hours, and oviposition usually takes place in the 

 stable before the manure is put in the pit or heap. When the larvae 

 are hatched they are driven to the surface by the heat of the under- 

 lying manure. 



According to Leleanf larvae cannot tolerate a temperature of 

 100 F. and are rapidly killed at any temperature above 114-8F. 

 In a closely packed heap of fresh stable manure the temperature 

 may range from 136 F. to 169 F. four inches below the surface, 

 which is fatal to both eggs and larvae. Roubaud draws attention 

 to the fact that the heat arising from the fermentation in a manure 

 heap may be used as a means of destroying the larvae that it contains. 



When a manure heap is turned over the larvae which come in 

 contact with the hot parts in the interior are killed at once. 



A complete stirring up of the manure on the day after the 

 deposition, and repeated on the two following days, causes a dis- 

 appearance, Roubaud says, of 90 per cent, of the larvae. 



Instead of placing new manure on the surface of the heap 

 it should be buried in the hot parts by covering all its surfaces 



* Vet. Journ., 1918, Vol. LXXIV., p. 74. 

 ^Sanitation in War, 1919. 



