necessary to catch or
otherwise destroy adult flies, or to protect food materials from
contamination and persons from annoyance or danger; hence the value of
fly papers and poisons, flytraps, and insect screens.

THE USE OF INSECT SCREENS.

A careful screening of windows and doors during the summer months, with
the supplementary use of sticky fly papers, is a protective measure
against house flies known to everyone. As regards screening, it is only
necessary here to emphasize the importance of keeping food supplies
screened or otherwise covered so that flies can gain no access to them.
This applies not only to homes but also to stores, restaurants, milk
shops, and the like. Screening, of course, will have no effect in
decreasing the number of flies, but at least it has the virtue of
lessening the danger of contamination of food.

Insect screens for doors and windows should be well made and must fit
tightly, otherwise they will not keep insects out. It is equally
important that they be made of good and durable screen cloth. Copper
insect screen cloth, although a little higher in price, will prove more
economical in the long run, as it lasts many years. If, however, the
cost of copper screen cloth is objectionable, steel screen cloth, either
painted or galvanized, can be used. Painted steel screen cloth will last
one or more years without repainting, its durability depending upon the
climate. In humid regions, of course, it will rust more quickly than it
will where the climate is dry. The same may be said of galvanized steel
insect screen cloth.

Insect screen cloth made with 16 meshes to the inch is recommended, for
16-mesh screen cloth will keep out flies and most mosquitoes[9] and
other small insects which at times are found almost everywhere.

[Footnote 9: Where the yellow fever or dengue fever mosquito occurs,
18-mesh screen cloth (or 16-mesh screen cloth made from extra heavy
wire) should be used.]

FLY PAPERS AND POISONS.

[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