NATURAL ENEMIES 
75 
during an early stage in the development of the insects. 
It is improbable that the worms develop to maturity 
in the fly, since they have been found only in the larval 
stage in that host. It might be noted in this connec¬ 
tion that Carter erred in identifying certain structures 
as reproductive organs.” 
Other nematodes have been found in the typhoid 
fly, but it is not as yet determined that they are surely 
distinct from the one just mentioned. 
The Mite Enemies of Musca Domestica 
Many flies of different species are often noticed to 
have small red mites attached to their bodies. This 
has been found to be the case with small flies as well 
as with large ones—even mosquitoes have enemies of 
this kind. Some of these mites probably exert a dele¬ 
terious effect upon their host and are true parasites, 
but with others the flies simply act as aeroplanes to 
carry the mites from one place to another. (A free ride 
seems to be the only object for which they have at¬ 
tached themselves to the fly.) 
Attention was called to these mites in the first place 
by DeGeer in 1735. Linnaeus wrote of one of them in 
1758, and other writers have made mention of them 
and have described several species. Mr. Nathan Banks, 
an authority upon this group of creatures (Arachnids), 
has given the writer the following information: 
“Latreille based a new genus and species on mites 
from the house fly, and he called it Atomus parasiticum. 
This is the young of one of the harvest mites of the 
