December, '16] dove-, wintering of house-fly 537 



In Breeding No. 66, the infested manure was placed in a cage and 

 inundated during two different periods which caused fermentation to 

 cease. This apparently rendered the condition for larvae more like 

 that of soil underneath a manure pile than that of pure manure. The 

 medium was a mixture of horse manure, cow manure and straw heavily 

 infested, and the individual cow droppings not being well broken up 

 probably served in protecting the larvae from drowning during the 

 inundations. 



Summary 



It should be understood that all of the observations dealt with in 

 this paper were made at Dallas, Texas. 



1. Adult house-flies having sufficient food, not subjected to fatal 

 temperatures, killed by Empusa musccv, nor destroyed by predators, 

 show increased longevity in indirect proportion to decreases in tem- 

 perature. 



2. The general tendency of adults to seek temperatures above 60° F. 

 necessarily causes a shorter longevity than 91 days, which was obtained 

 in a most favorable abnormal caged condition. 



3. The humidity being normal and adults being prevented from 

 warmer temperatures they become inactive at 45° F., crawl slightly 

 at 48° F., and will voluntarily fly at 53° F. Even previously fed 

 adults, if subjected to freezing temperatures, die in less than three days. 



■ 4. "Northers," causing sudden drops in temperature, are responsi- 

 ble for a large mortality of flies in the vicinity of Dallas, Texas, yet 

 warm periods occur during mid-winter which permit depositing. 



5. There is a possibility that epidemics of Empusa muscce may be 

 caused by a lack of deposition media for flies which are sexually matured 

 and have copulated. 



6. Breeding media ranging from 46° F. to 55° F in twelve hours will 

 permit emergence of adults from puparia, but emergence has never 

 been observed at lower temperatures. 



7. Great numbers of pupae near the surface of the soil receive either 

 enough heat to permit emergence of adults which usually succumb to 

 cold before depositing or the temperatures are so low that they become 

 inviable. 



8. Young larvae have been kept for more than 67 days without 

 pupating, but only by occasional additions of small amounts of fresh 

 manure. 



9. Larvae more than one-half normal size have been kept alive for 

 more than 90 days, and still other larvae of various sizes have been ob- 

 served to live for 115 days. 



