The House Fly and How to Suppress It | Page 5

of a weak solution of formalin. A very
effective fly poison is made by adding 3 teaspoonfuls of the
commercial formalin to a pint of milk or water sweetened with a little
brown sugar. A convenient way of exposing this poison is by partly
filling an ordinary drinking glass with the solution. A saucer or plate is
then lined with white blotting paper cut the size of the dish and placed
bottom up over the glass. The whole is then quickly inverted and a
small match stick placed under the edge of the glass. As the solution
evaporates from the paper more flows out from the glass and thus the
supply is automatically renewed.
FLY SPRAYS.
Sprays designed to destroy or repel house flies fill a certain need in
connection with the house-fly problem. No very satisfactory repellent
substances for this insect have been found which are at the same time
adaptable to general use about the home, or places where foods are
handled. Extracts of pyrethrum flowers are now generally available
commercially, and these give fairly good results in the destruction of
house flies in buildings. Most of the sprays of pyrethrum extract
contain kerosene oil as a carrier, and undoubtedly the kerosene has
much to do with the toxicity of the spray. Such materials are most
applicable to buildings which become infested with flies and which can
be readily closed up at night and the air within thoroughly saturated
with the spray by means of an atomizer. Under such conditions the flies

are rather quickly overcome by the spray and if a sufficient quantity is
used they will not revive.
FLYTRAPS.
Flytraps may be used to advantage in decreasing the number of flies.
Their use has been advocated not only because of the immediate results,
but because of the chances that the flies may be caught before they lay
eggs, and the number of future generations will be reduced greatly.
Many types of flytraps are on the market. As a rule the larger ones are
the more effective. Anyone with a few tools can construct flytraps for a
small part of the price of the ready-made ones. A trap (fig. 8) which is
very effective in catching flies and is easily made, durable, and cheap,
may be made of four barrel hoops, four laths, a few strips of boxing,
and 8 1/2 lineal feet of screening, 24 inches wide. (For greater details
see Farmers' Bulletin 734.)
The effectiveness of the traps will depend on the selection of baits. A
good bait for catching house flies is 1 part of blackstrap molasses to 3
parts of water, after the mixture has been allowed to ferment for a day
or two. Overripe or fermenting bananas crushed and placed in the bait
pans give good results, especially with milk added to them. A mixture
of equal parts brown sugar and curd of sour milk, thoroughly moistened,
gives good results after it has been allowed to stand for three or four
days.

PREVENTING THE BREEDING OF FLIES.
As previously stated, fly papers, poisons, and traps are at best only
temporary expedients. The most logical method of abating the fly
nuisance is the elimination or treatment of all breeding places. It would
appear from what is known of the life history and habits of the common
house fly that it is perfectly feasible for cities and towns to reduce the
numbers of this annoying and dangerous insect so greatly as to render it
of comparatively slight account. On farms also, in dairies, and under

rural conditions generally, much can and should be done to control the
fly, which here, as elsewhere, constitutes a very serious menace to
health.
CONSTRUCTION AND CARE OF STABLES.
In formulating rules for the construction and care of stables and the
disposal of manure the following points must be taken into
consideration. In the first place, the ground of soil-floor stables may
offer a suitable place for the development of fly larvæ. The larvæ will
migrate from the manure to the soil and continue their growth in the
moist ground. This takes place to some extent even when the manure is
removed from the stables every day. Even wooden floors are not
entirely satisfactory unless they are perfectly water-tight, since larvæ
will crawl through the cracks and continue their development in the
moist ground below. Water-tight floors of concrete or masonry,
therefore, are desirable. Flies have been found to breed in surprising
numbers in small accumulations of material in the corners of feed
troughs and mangers, and it is important that such places be kept clean.
FLY-TIGHT MANURE PITS.
The Bureau of Entomology for a number of years has advised that
manure from horse stables be kept in fly-tight pits or bins. Such pits
can be built in or attached