524 Observations on Habits and Parasites of Common Flies 
the maximum temperature, especially in the spring, was not infrequently 
many degrees higher in the “ sun ” than in the “ shade tin.” The daily 
variations in temperature were therefore much greater in the “sun” 
than in the “shade tin.” 
On April 11, 1915, the earth containing the pupae was collected from 
the bottom of each tin and placed in a small wooden box with a balloon 
trap fixed over an opening in the lid. The box was replaced in its tin. 
The object of this procedure was to catch any flies which might emerge 
from the pupae, but at the same time to leave the pupae in their 
respective tins in which slightly different conditions prevailed. On 
April 22 Anthomyid flies began to emerge in both boxes, and on April 23 
blow-flies. The blow-flies emerged in great numbers from the “shade 
box” and continued to do so up to May 11; altogether 987 blow-flies, 
58 F. scalaris, 10 H. dentipes, 12 T. canescens were obtained from 
this box. In the “sun box” on the other hand only 16 blow-flies 
and one small fly emerged between April 23 and May 2. After the 
flies had ceased to emerge numbers of large braconids made their 
appearance. Between May 15 and 29 twelve of these braconids emerged 
in the “sun box,” while between May 17 and June 16 at least 209 
emerged in the “shade box.” As a few managed to escape through 
the mesh of the trap the complete total is unknown in each case. 
After this a period of three months elapsed in which neither flies 
nor braconids emerged, but on Sept. 19 further braconids commenced 
to emerge in the “shade box” and continued to do so until Oct. 15, 
at least 1115 appearing during this period. 
As this observation is of some interest, and may be of some import¬ 
ance, Chart 9 is inserted showing the dates on which the braconids 
emerged. 
The individuals emerging in the spring were much larger than those 
which emerged in the autumn. Males and females emerged both in 
the spring and autumn. (See p. 531.) 
No braconids emerged from the “sun box” after May, and no second 
batch of flies emerged from either box. 
Mr Gl. T. Lyle very kindly identified these braconids as Alysia 
manducator, and stated that those which emerged in the spring and the 
autumn belonged to the same species. 
On various occasions this species of braconid was seen laying eggs 
on large maggots feeding on carcases of large and small animals, but no 
evidence was obtained that they are capable of ovipositing in pupae. 
There can be therefore little doubt from the conditions under which 
