150 Psyche [October 



different times during the winter. These adults were killed when 

 a temperature of 28° was reached on January 2, 1913. The imma- 

 ture stages, however, remained in perfect condition throughout 

 the cold weather, and undoubtedly large numbers will emerge 

 in the spring. In the laboratory, emergence continued through- 

 out the winter. The greatest number appeared from pupae kept 

 in glass tubes in a well heated room. In another room, in which 

 the temperature ranged somewhat lower, emergence was less rapid. 

 At temperatures from 55 to 60° F. the adults became inactive. 

 Breeding progresses well at 70° and somewhat higher temperatures 

 increase all activities. Adults kept at 110° (in the dry atmosphere 

 of an incubator) died very quickly. 



Habits. 



The adult parasites are scavengers in habit. In cages no pre- 

 pared food is necessary for them. They prefer to feed on the re- 

 mains of the host, and very often crawl back into the puparium and 

 stay there for some time. While within the puparium they have 

 been observed to feed upon the remains of the dipterous pupae 

 although honey and water were at hand. In no case did the 

 adults pay much attention to artificial foods. They are seldom 

 found anywhere except in and around the breeding places of their 

 hosts. In flight the body is held in a vertical position with head 

 up and wings extended horizontally. When disturbed, both sexes 

 have the habit of "possuming." The legs are drawn together 

 and the insect drops for a few seconds and then quickly resumes 

 activity in order to escape. It appears that the parasites remain 

 in one place as long as they have plenty of fly pupae to parasitize. 

 Probably dispersion takes place when the parasites become nu- 

 merous and they do not have a sufficient number of hosts. It 

 has been found that each female requires a considerable number 

 of pupae in which to deposit her eggs. 



After the adults emerge from their pupal skins they have the 

 habit of remaining within the puparia of the host for some time. 

 During this period they gnaw more or less regular, circular holes 

 through the puparia, but in many cases do not issue for some time 

 after the emergence holes have been made. 



