424 THE CANADIAN ENTOMOLOGIST 



freed last. The time required for a fly to free itself usually dees 

 not exceed one-quarter of a minute, and frequently it has been 

 found that the extrication is accomplished within 4 or 5 seconds. 

 It may even further be hastened if the water is suddenly jarred. 

 In that case the adult can cast off the pupal skin in one second. 

 Sometimes the fly fails to get out of the pupal covering, on account 

 of pulling out the tip of the abdomen too soon. There is a natural 

 order for the extrication of the difi^erent parts of the insect's body 

 OS mentioned above, any departure from which will result fatally. 

 Experiments Upon the Longevity of the Adults. — The following 

 experiments were performed on the imagines reared in the labora- 

 tory. The imagines were confined immediately after their escape 

 from the pupal skin. Their confinement was near a window where 

 they Avere exposed to the sunlight during several hours of the day 

 and care had been taken against excessive heat: 



I. An imago was kept in a bell jar under which some lumps 

 of CaCb were placed. The humidity inside was reduced prac- 

 tically to zero. The fly lived therein for only 24 hours. (Sept. 

 23-24). 



II. An imago was kept in a jar in which the moisture was 

 maintained in a moderate condition through the evaporation of 

 the water in a small dish placed underneath. It lived for 45 

 hours. (Sept. 23-25.) 



III. An imago was kept in a jar in which the moisture was 

 maintained to saturation by keeping Elodea and Sphagnum, un- 

 derneath by sticking a few pieces of fully saturated blotting paper 

 to the inner surface of the glass and by wetting the cheese-cloth 

 that covered the top from time to time. The fly favoured by such 

 condition lived for six days. (Sept. 23-29). 



Under natural conditions, in the day time they are found in 

 the grasses, rushes and sedges growing on the shore in moist situa- 

 tions, and consequently, there is every reason to believe that the 

 imagines may survi\e much longer in such places than in con- 

 finement. 



Effect of Loiv Temperature, Wind and Smoke upon C. decoriis. — 

 The imagines behave themselves very much like other insects with 

 regard to their activity under varying conditions of temperature. 

 In the summer season, if it has been a clear, hot day, they are 



