sticky fly papers to destroy flies that have gained access to
houses is well known. Fly-poison preparations also are common. Many of
the commercial fly poisons contain arsenic, and their use in the
household is attended with considerable danger, especially to children.
This danger is less with the use 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 che