I50 



Journal of Agricultural Research voi.xm,No.3 



Table I. — Longevity of house flies during winter in cages under outdoor conditions 



Experi- 

 ment No. 



M-i 



M-2 



M-3 



1914. 

 Oct. 18 



Nov. 12 



Nov. 15-17 



M-7. 

 M-8. 



3-A. . 

 4-A2. 

 5-Ai. 

 S-A2. 

 5-A3- 

 S-A4- 

 ii-i . 



M-20 



Date of 

 emergence. 



Nov. 27 

 Nov. 27 



Nov. 6 



Nov. 3 



Nov. 2 



Nov. 12 



Nov. 2 



Nov. 7 



Nov. 1 1 



1915- 

 Mar. 



Remarks. 



Minimum temperature of iS° F. 

 occurred November 24. 



Minimum of 10° F. occurred on 



December 15, 1914, a. m. All 



appeared dead but were kept 



ininsectary till Feb. 12, 1915, 



then taken to greenhouse, 



but none recovered after 



several days in a warm room. 



[Minimum temperature of 10° F, 



I occurred December 15, 1914, 



I a.m. No recovery after several 



[ hours in warm greenhouse. 



Reared in greenhouse and 

 given time for one feeding 

 before being taken outdoors. 

 Continued cold prevented 

 any feeding after removal to 

 insectary. 



In these and other experiments it was found impossible to keep house 

 flies alive during the winter in cages under outdoor conditions in spite 

 of the presence of food and shelter afforded by the mass of food material 

 and the corners of the wooden framework of the cages. It was found 

 that the first really cold night of the winter (December 15), when the 

 temperature fell as low as 10° F., proved fatal. No flies revived after 

 exposure to this temperature even when kept several hours or even days 

 in a warm greenhouse. On the other hand, after exposure to tempera- 

 tures of 22° or 25°, a large percentage often revived. Continued exposure 

 to low temperatures which interfere with normal activities, especially 

 feeding, will eventually prove fatal, as was the case in experiment M-20, 

 Table I. Since at this latitude temperatures often fall below 10° during 

 the winter, the foregoing experiments point to the conclusion that house 

 flies in the adult state can not pass through the winter when exposed to 

 outdoor conditions. 



