598 CutH PING 
Beginning of pupation Emergence of adults Number of day 
August 2 August 4 2 
August 4 August 13 9 
August 8 August 13 5 
- According to the foregoing data, the length of the pupation period 
varies from two to eleven days. In the field, during hibernation, the 
period extends over four or five months. 
Relation to environment 
In different kinds of soluttons 
A number of pupae were kept at the bottom of a salt-water aquarium. 
Within ten days many flies emerged. The emergence of about the same 
number of pupae kept in tap water tceok place much later. In 5-per-cent 
formalin, adults emerged from the puparia floating on the surface, but 
in kerosene all the puparia sank to the bottom and none of the pupae 
developed. 
When exposed to air 
From the salt pocls a stick of wood with numerous pupae attached was 
brought into the laboratory. Before the laboratory was reached, a few 
flies emerged. More continued to emerge in the laboratory before this 
piece of wood became entirely dry. 
Effect of excessive heat 
High temperature, within a certain limit, favors the development of th 
pupa and hastens the emergence of the adult. During the latter part o 
July the temperature in the laboratory registered about 30° C. The 
pupae kept in the laboratory did not show any unusual speed in develop- 
ment. After several days of sunny weather, the temperature rose steadily, 
registering between 39° and 40° C. at noon. Under each of three bel 
jars, from twenty-two to twenty-four half- or full-grown pupae wer 
placed. At the end of the first day, from three to five adults ha 
emerged in each jar; two days later the number had increased to six or eight: 
and at the end of the sixth day, to fifteen or twenty. This is assumed a 
the highest temperature the pupae could stand in the presence of plent 
of moisture. In order that this assumption might be verified, the same 
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