546 Cc. H. RICHARDSON 
cytes have been seen in sagittal sections of the mesenteron. 
Recently ingested particles lying near the anterior region of the 
mesenteron are broken up and smaller than corresponding par- 
ticles found in the abdomen of the fly pupa and I feel confident 
that a certain amount of digestion takes place outside the body. 
The salivary glands are hugely developed and well situated to 
secrete a ferment necessary for this. 
HIBERNATION 
The winter is probably passed in the pupal stage. I have 
found pupae and even semipupae late in February in fly puparia 
which were parasitized in October. The development is un- 
doubtedly greatly retarded during the winter season. 
ECONOMIC IMPORTANCE 
This problem was undertaken too late in the fall to obtain 
definite results regarding the economic importance of this: para- 
site. The highest proportion of parasitized house fly puparia was 
noted on October 5, 1912, when 9 Spalangia larvae and pupae 
were removed from 22 puparia. On another occasion, 5 larvae 
and pupae were taken from 101 fly puparia. 
At Forest Hills, Massachusetts, I have reared this parasite 
with certainty only from puparia of the house fly. However, 
Stomoxys calcitrans was breeding quite abundantly with the 
house fly in a region infested with Spalangia muscidarum, and 
it seems reasonable to suppose that there was no discrimination 
shown between the two. 
Bishopp (713) found Spalangia muscidarum to be a parasite 
of Stomoxys calcitrans, Haematobia serrata and Musca domes- 
tica in Texas. In an examination of 2500 puparia of Stomoxys, 
40 per cent were found to be parasitized by this and another 
undetermined Pteromalid. 
In one instance, a large number of adult Spalangia were reared 
from puparia late in August. This leads me to believe that 
there are at least two regular generations and a third more or 
less regular one annually in Massachusetts. The first generation 
will emerge from the over-wintering pupae as early in the spring 
7 
