HABITS OF THE ADULT FLY 59 



number of flies by August 2Oth. Major N. Faichnie, 

 referred to above, in experimenting with flies in India 

 in the summer, found that they lived eleven days only. 

 Mr. Jepson, in his notes on the breeding of the com- 

 mon house fly during the winter months, incidentally 

 mentions the fact that during the summer of the pre- 

 vious year (1908) in no case was he able to keep flies 

 alive for more than three weeks, and then only with a 

 few individuals; whereas, as previously stated, flies 

 reared during the winter were kept alive for eleven and 

 one-half weeks, and flies caught in kitchens in Febru- 

 ary were kept alive for ten weeks and had presumably 

 been living since the previous autumn. 



If we take Jepson's statement of three weeks as be- 

 ing the probable limit of the life of the adult fly in 

 midsummer, and if we conclude, as we must, that the 

 average life at that period is much shorter than this, 

 it becomes evident from what will be stated in the fol- 

 lowing paragraph that after the female fly has laid her 

 eggs in summer she has not much longer to live. The 

 plain inference from this will naturally be that the hi- 

 bernating flies in the winter time are probably for the 

 most part females which have not laid their eggs. Un- 

 fortunately for the conclusions just stated, Doctor 

 Hewitt records the fact that he has kept flies in cap- 

 tivity in the summer time for seven weeks, while Grif- 

 fith (1908) was able to keep a male sixteen weeks. 



Ficker (1903), in an account of experiments carried 

 on between June and October, states that he kept flies 

 alive in confinement for four weeks, feeding them on 



