454 Observations on Habits and Parasites of Common Flies 
later than F. scalaris in “ Tin I ” and 0. leucostoma commenced to 
emerge when the mean two-inch temperature reached 58° F. 
Forty-seven pupae and thirty-five blow-fly larvae removed from the 
earth in an experimental cage outside were brought into a warm room with 
a maximum daily temperature of 52° F. on Jan. 14, 1916. The larvae 
soon pupated and seventy-nine flies emerged between Feb. 14 and 24. 
The transference to the warmer temperature had caused the larvae to 
pupate, and flies to emerge in thirty to forty days. In the outdoor 
cage the first fly appeared on April 1. (See Table I.) 
Pupae and earth taken from “Tin II"’ on Feb. 29, 1916 were placed 
in jars and kept in different rooms. Room A facing east had no fire, 
room B had a fire daily, and rooms C and D were warmed by the kitchen 
chimney and a hot-water cistern respectively. Room E was a kitchen. 
The jars, “Tins” and outside cage were examined daily, and the flies 
caught and recorded. The results of these experiments are given in 
Table I. It will be seen that in room E with a mean temperature of 
60° F. flies began to emerge in five days, in rooms B, C and D in fourteen 
days, but not till the thirty-third day in room A. Outside they emerged 
earliest in “Tin II,” next in “Tin I,” and later in the outdoor cage 
with the lowest mean temperature. It will further be noticed that in 
all cases a mean temperature of 48° F. had prevailed for a period before 
large numbers emerged. In this series of experiments, except in the 
outdoor cage, the only varying condition was the temperature 1 . 
Until further evidence is available it may be permissible to put 
forward the tentative hypothesis that the majority of specimens of each 
species only emerge after the mean temperature of the materials in 
1 Out of doors greater daily variations in temperature occurred than indoors. 
Note on Charts 1, 2, 5 and 7. 
The daily mean temperature in “Tin I” and the daily mean temperatures of the earth 
at a depth of one foot in the open and in the shade, and at a depth of two inches in a partly 
shaded situation, and the daily mean temperature on the surface of the ground during 
April, May and June, 1915, are given in Chart 1. The daily minimum temperature on 
the grass, and the daily mean temperature of the earth at a depth of one foot in the 
shade and at a depth of two inches from April to December, 1915, are given in Chart 2. 
The daily maximum temperature recorded by a thermometer exposed to the sun, from 
May to November, 1915, is given in Chart 5. The daily maximum and minimum tempera¬ 
tures in the screen from May to November, 1915, are given in Chart 7. 
The total daily rainfall from April to December is given in Chart 2 and the rainfall 
occurring in the daytime and at night in Chart 7. 
The total daily hours of bright sunshine between 8 a.m. and 6 p.m., from May to 
November, are given in Chart 5, and the daily periods of bright sunshine in Chart 7. 
