Evening star. [volume] (Washington, D.C.) 1854-1972, 1875-12-16
The Use OF the Common House Fly

We are accustomed to consider flies as a
nuisance, but according to Mr.. EN- rSOn, an
part in the economy of nature. Mr.. Emer-
son states that he began his self-appointed
task of finding out whether the house fly
really serves an appreciable purpose in the
scheme OF creation, excepting as an indiffer
ent scaveDger, by capturing fine specimen
and gluing his wings down to a micrOsC Ope
slide. On placing the slide under the instru-
ment, to the Investigators disgust the fly
appeared covered with lice, causing the
offending insect to be promptly released and
another substituted m his place. Fly No.
might be predicted of flies 3, 4, (or of u flies
as The algebras have it), Mr.. Emerson con-
clLded that here was something which at
once required looking into. Why were the
flies lousy? Meanwhile fly No. 2, on the
slide, seemed to take his position very coolly.
and, extending his prObOscis, began to sweep
1T over his body as If he had just alighted.
A glance through the microscope, however,
showed that the operation was not one OF the
Identification; for wherever the lice were,
there the trunk went. The lice were disap-
pear1ng into the trunk; the fly was eating
Them. Up tn this time the Investigator had
treated his specimen as of the masculine
gender; but now he changes his mind and
concludes II to be female, busily devour
Ing, not lice, but her own progeny. The flies
then carry their young about them; and
when the family get too numerous, the
mother too hungry, the offspring are eaten.
Awhile reasoning thus, Mr.. Emerson picked
up a scrap OF white writing paper, from
which two flies had appeared to be busily
eating something, and put 1t under the in
strument. There were the progeny again on
the paper, and easily rubbed Off with q cloth.
81 his, ;" he says, "set me thinking. / took
the paper into the kitchen again and
waved IL around, taking care that no flies
touched 1t; went back to the microscope and
there found animalcules, the same as on lies.
had now arrived at something definite,
they were not the progeny OF the fly, but
animalcules floating in the air; and the
quick motions of the flies gathered them on
their bodies, and the flies then went into
some quiet corner to have their dainty
meal" The Investigator goes on to describe
how he continued the experiment in var.e-
~ of localities, and how, in dirty and
badly smelling quarters, he found the
myriads of flies which existed there literally
covered with animalcules, while other flies
captured in bedrooms or well-ventiiate L.
clean apartments, were miserably lie IN and
entirely free from their prey. Wherever
NTH existed, evolving germs which mi light
generate disease, there were the flies cover.
ing Themselves with the minute organism
and greedily devourfng the same.
1t remains now for some INVESTIGATOR to
discover the use ofthe mosquito. Some one
has said that nature created them in order to
compel us, in self defense, to drain our
marshes and cultivate our waste lands. 1t
may well be, however, that, like the fly,
they also prey on animalcul@, and thus rid
us of greater pest than they are them
selves.