Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1915-01-01
THE FLIGHT OF FLIES.

One of the problems that has arisen
in connection with the part played by
insects as carriers of disease concerns
the distance which they may be able
to travel from one locality TO another.
This has frequently been considered in
this country in connection with mos
quitoes which are responsible for the
prevalence of malaria. With their
breeding-places known, it has become
desirable in some cases to ascertain
what the range of their activities
might be in respect to the territory
which can be covered by insects. 1t
has been learned that mosquitoes
which inhabit salt marshes near the
seacoast may be found inland at dis
stance as great as three miles.
Far less appears to be known with
regard to the migrations of the COM
mon house-f1y, an insect charged with
responsibility for typhoid fever and
other infectious diseases. A series of
studies conducted in Cambridge, Eng
land, on the range of the flight of flies
of this species has been made the sub
ject of a report TO the local govern
ment board on public health and medi-
cal subjects. Upward of $4,000 flies
were liberated, under various meteoro-
logic conditions, from the medical
buildings at Cambridge. OF these in
sects, colored for identification, 191
were recovered. The results showed
that house-iies tend to travel either
against or across the wind. The actual
I'll II ha
either directly and by the action of the
wind, or indirectly owing to the flies
being attracted by odors from food. A
point in favor of this superstition is
the nature of the station at which flies
we're recovered after they had travelled
any distance These comprised
butchers shop, public houses and
restaurant, all of which gave off doors
that are VIGOROUSLY attractive to Hies
The chief conditions favoring the dis /
posal of flies are fine weather and /
warm temperature. The nature of the
locality is another considerable fac /
tor because in towns flies do not
travel as far as in open country. prob /
ably due to the food and shelter afford /
ed by the houses. With regard to the
altitude of the point of liberation, flies I
set free from the roof tended to dis
perse slightly better than those liberat- !
ed from the ground, but the differences |
are not very considerable. It has been I
observed, with regard TO the vertical !
fight OF the house-1y, that il may /
mount almost directly upward to
height of IS feet or more. The time of
day appears TO influence the dispersal /
of the insects, as, apparently, when set
free in the afternoon they do not scat |
ter so well as when liberated in the 1
morning
The maximum fight observed In the |
thiekly housed localities in Cambridge /
was about a quarter of mile. In one |
case, where a part of the distance was
across open fenland, a flight OF 40 /
yards was noted. In experiments con- !
Quoted in Cook county, Illinois, by S. /
A. Forbes, flies We're trapped and, after |
being sprayed with chemical solution |
for recognition, were liberated from |
hospital in that district. They, too, |
were recovered at distances ranging I
I'D to a quarter of mile from the
point of liberation The distance flies |
NAV travel to reach dwellings is con-
trolled by circumstances. Almost any
distance may be covered by
the fly under compulsion to reach food /
and shelter.