246 THE HOUSE FLY—DISEASE CARRIER 
summarizes his conclusions in the following words: 
“It may be regarded as proved that Stomoxys calcitrans 
L., as also A. nigra, Macq., and probably other species 
of the genus, can convey trypanosomes directly from 
an infected to a healthy animal, when the bites follow 
one another immediately. On the other hand, the evi¬ 
dence tends to show that when the interval between 
the bites is longer (the maximum period within which 
a bite is infectious has not yet been determined), al¬ 
though active trypanosomes may be present in the in¬ 
testine of the fly, its life is innocuous. There is no 
indication that trypanosomes ingested by A. calcitrans 
pass through a developmental cycle, and they appar¬ 
ently disappear within twenty-four hours. With re¬ 
gard to diseases other than trypanosomiases, there are 
some grounds for thinking that A. calcitrans, like other 
biting flies, may occasionally disseminate the bacillus 
of anthrax, and, in Europe, it would appear that the 
fly is the intermediate host of a species of Filaria para¬ 
sitic in cattle. 
The Little House Fly 
(Fannia [ Homalomyia ] canicularis L.) 
In discussing the size of the adult house fly in Chap¬ 
ter I, we mentioned this little fly which is found rather 
commonly upon window-panes in houses, and stated 
that it was the source of the prevalent error to the 
effect that house flies grow after they become winged 
and that these little flies are the young of the larger 
flies. They belong, however, not only to an entirely 
