U. S. Graham-Smith 
527 
When the great difference in the number of flies emerging from the 
two boxes became apparent, an experiment was tried to ascertain 
whether the difference was due to the effects of the somewhat greater 
cold during the winter in the exposed “sun tin,” or to the effects of 
the high temperatures or great daily oscillations in temperature 
developed in that “tin” by exposure to the sun in the spring months. 
For this purpose on April 29,1915, a number of pupae were removed 
from the “shade box” and placed in a separate receptacle in the “sun 
tin,” and some from the “sun box” were similarly placed in the “shade 
tin.” It was found that flies and braconids continued to emerge from 
the pupae transferred from the “shade” to the “sun tin,” but that 
none emerged from those transferred from the “sun” to the “shade 
tin.” At first sight it seemed evident that it was the difference in the 
winter conditions which influenced the pupae. Further observation 
showed, however, that this was an erroneous conclusion and that the 
difference was due to further parasitism by chalcid parasites (p. 529). 
On May 6 some of the unbroken pupae from the “sun box” were 
examined, and nearly all were found to contain single living braconicl 
larvae in an advanced stage of development. On May 22 pupae from 
the “shade box” were examined; the larger ones were empty, blow¬ 
flies and braconids having emerged from them, but the medium sized 
and small pupae contained braconicl larvae as in the “sun box.” 
In November, 1915, as there did not seem to be any prospect of 
further flies emerging from these boxes, the puparia in each were 
carefully examined. 
On comparing the puparia remaining in the boxes with specimens 
from which either flies or braconids had emerged, it was not difficult 
to ascertain whether a fly or a braconid had emerged from a given 
puparium. In the act of emerging a fly pushes off the anterior end 
of the puparium in a characteristic fashion (see p. 449). On the 
other hand the braconid emerges by gnawing an irregular oval hole 
near the anterior end of the puparium (Plate XXX, fig. 9). A single 
specimen of A. manducator emerges from each puparium. In many 
examinations of puparia just before the emergence of the parasite it 
was found that the head of the braconid was always at the anterior 
end of the puparium. 
Puparia from which flies and braconids have emerged can also be 
differentiated in another way. A puparium from which a fly has 
emerged is fined by a very thin, almost transparent, brittle membrane; 
