82 THE HOUSE FLY 



other decaying substances such as stable manure. It lays 

 an average of sixty eggs at a time, in a heap. These 

 eggs, which are very similar in appearance to those of 

 the House Fly, hatch out in two or three days' time, if 

 the temperature be suitable, viz. 72 F. to 75 F. during 

 the daytime, and if not lower than 65 F. during the 

 night. The grubs or larvae take from fourteen to twenty- 

 one days to become full-grown if the conditions are suitable. 

 Should the fermenting substances on which they feed 

 become somewhat dry, and if even a little light should 

 penetrate to their feeding-grounds, the development of 

 the grubs is retarded, and they will not reach maturity 

 for a month. Should the conditions for quick development 

 be very unfavourable, they will take nearly three months 

 to mature. After changing into the pupa or chrysalis 

 condition, an interval of from nine to thirteen days passes 

 before they emerge as full-grown Biting Stable Flies. It 

 is believed that this species of fly passes the winter chiefly 

 in a pupal or chrysalis condition. 



There can be no doubt that this Biting Fly, and others 

 of the same kind, all of which are generally termed Blood- 

 sucking Flies, are capable of carrying blood parasites from 

 one animal to another, or from one human being to another 

 in the manner already outlined. Apart from its power 

 to inoculate healthy animals, and even man, with disease 

 germs, its bite alone often produces serious results in 

 cattle, for it has frequently been noticed that when such 

 animals are bitten on the legs and shoulders by Blood- 

 sucking Flies the joints become swollen, often so much 

 so that the animals are unable to bend their legs and 

 consequently cannot lie down. Often the inflammation 



