6 THE LIFE-HISTORY OF THE BLOW-FLY. 



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 1889 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 pupte. 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. 



TUB FLESH-FLY. 

 I^Sareophaga caniaria. ) 



