6 THE LIFE-HISrOR \ ' OF THE BLO W-FL V. 



our dwellings until late in autumn, although they abound in 

 butchers' shops, slaughter-houses, and similar places. 



The question of hibernation is a difficult one to settle. All 

 ' winter flies ' are, I believe, immature, as I have never found 

 one with ripe eggs ; still, I strongly suspect mature females 

 hibernate occasionally. 



In the winter of 1SS9 I had a bell-glass in my laboratory full 

 of immature blow-flies, which had recently issued from the 

 pupae. One very cold morning when I went in not a fly was to 

 be seen. I imagined the bell-glass had been lifted, and that 

 my flies had escaped. On closer investigation, however, I 

 discovered them all closely huddled together in a hollow under 

 the base of a cup containing pupae. The cup had been slightly 

 tilted, and every insect had retreated into this narrow space. 

 As soon as the temperature of the room rose to 55" Fahr., the 

 insects emerged from their concealment, and were as lively as 

 ever. 



THK FLESH-FLY. 

 {Sarcop/iaga carnaria. ) 



