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 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.