60 THE HOUSE FLY DISEASE CARRIER 



sugar, bread, water, or milk. Unfortunately he does 

 not give the exact dates of this particular observation, 

 and it may have been on an October generation, which 

 would have hibernated. 



Time Elapsing Betiveen the Issuing of the Adult and 

 the Period of Sexual Maturity 



The practical value of the determination of this 

 period is very great. If an adult female fly can be 

 destroyed before she lays her eggs, we will have killed 

 not only the actual fly, but 120 to 600 potential flies 

 due in a very short time, and if this female fly can be 

 caught in the early spring the table on an earlier page 

 will indicate that instead of performing a very simple 

 act we have apparently saved the world from almost 

 a calamity. From this can be seen the value of fly 

 traps. Of course the destruction of breeding places 

 is very important, but traps for adult flies are by no 

 means to be despised when we have this idea in view ; 

 and the use of fly traps in the early part of the season 

 becomes obviously all-important. The destruction of 

 hibernating flies is equally of value ; but these subjects 

 will be considered in the chapter on remedies. 



So far as the writer knows, the only observers who 

 have paid any attention to this very important point 

 of the period elapsing before sexual maturity are 

 Hewitt (1910) and Griffith (1908). Hewitt states 

 that he found flies become sexually mature in ten to 

 fourteen days after emergence from the pupal state, 

 and that four days after copulation they begin to de- 



