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 depend ing 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.

FLY PAPERS AND POISONS.

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.

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 8½ 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 to the stable so that manure can be easily thrown in at the time of cleaning and so constructed that the manure can be readily removed. It is desirable that the manure be placed in these fly-proof receptacles as soon as possible after it is voided. The essential point is that flies be prevented from reaching the manure, and for this reason the pit or bin must be tightly constructed, preferably of concrete, and the lid