December, '16] dove: wintering of house-fly 529 



In Table I, in which experiments no Empusa occurred, adults were 

 not subjected to fatal temperatures, and received an abundance of 

 food. It will be observed that the longevity was prolonged as the 

 temperatures decreased and in once instance a fly lived for 91 days. 

 This maximum longevity is a record obtained under the most favorable 

 abnormal conditions which I find are not utilized by adults in nature. 

 It is well to know the conditions under which this maximum longevity 

 was obtained. 



A room, in which a box was placed containing hundreds of pupae in 

 infested cow manure, was gradually heated to a maximum of 70° F. 

 and the temperature allowed to remain about the same for thirty-six 

 hours. During this time 600 adults emerged into a 4' x 4' x 5' cage 

 and all apparently fed soon after emerging. Ripe bananas, sweet 

 milk, and fresh cow manure were present, and at short intervals 

 during the longevity these were freshly replenished. No hibernation 

 material was supplied for as near as possible the actual temperatures 

 experienced by the adults was desired. Five days later, on December 

 17, the room was again gradually heated to 70° F. and allowed to remain 

 for a short time to insure a second feeding. Great activity was mani- 

 fested and apparently all again fed. The cage was located in the 

 coldest room on the north side of a two-story frame house, and except- 

 ing the two periods of artificial heating to insure feeding of adults 

 I believe the temperatures most favorable for a maximum longevity 

 were obtained. Between the first and second feeding of the adults a 

 minimum of 20° F. occurred, but was present only a few hours. Dur- 

 ing this time sixty adults died, but this was probably only an elimina- 

 tion of those not sufficiently fed, as will be seen from a study of efi'ect- 

 ive temperatures discussed in a later paragraph. iVfter the second 

 feeding of the adults a minimum of 32° F. occurred on December 26, 

 and a minimum of 28° F. on January 24, but neither of these continued 

 long enough to greatly affect the mortality. An average of the daily 

 minimum temperatures during the longevity period was 42.58° F., 

 an average of the daily maximum temperatures 57.66° F., while the 

 daily mean average was 50.12° F. The room in which this experiment 

 was conducted was used for no other purpose, for the reason that the 

 movement of persons and the warmth of their bodies would have 

 increased the temperatures, thereby increasing the activity of flies. 

 It was also partially darkened by window shades which kept out the 

 sunlight and lessened activity. This, however, did not prevent feeding 

 of adults during the warmer portions of the day. On some days it was 

 warm enough to permit flight, and had the flies not been caged they 

 would have then sought the warmer portions of the house. Being 

 caged they were allowed to feed but were necessarily kept quiescent 



