[Illustration: FIG. 8.--Conical hoop flytrap side view. _A_, Hoops
forming frame at bottom. _B_, Hoops forming frame at top. _C_, Top of
trap made of barrel head. _D_, Strips around door. _E_, Door frame. _F_,
Screen on door. _G_, Buttons holding door. _H_, Screen on outside of
trap. _I_, Strips on side of trap between hoops. _J_, Tips of these
strips projecting to form legs. _K_, Cone. _L_, United edges of screen
forming cone. _M_, Aperture at apex of cone. (Bishopp.)]
The use of 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.