In order to retain the fertilizing value of manure to the greatest extent, it is advisable to exclude the air from it as much as possible and to protect it from the leaching action of rains. This being the case, there is really no necessity to cover a large portion of the top of the box with a trap, but merely to have holes large enough to attract flies to the light and cover these holes with ordinary conical traps with the legs cut off so the bottom of the trap will fit closely to the box. The same arrangement can be made where manure is kept in a pit. In large bins two or more holes covered with traps should be provided for the escape of the flies. Manure boxes should be used by all stock owners in towns and cities, and they are also adaptable to farms. The size of the manure bin should be governed by the individual needs, but for use on the farm it is desirable to make it large enough to hold all of the manure produced during the busiest season of the year. A box 14 feet long, 10 feet wide, and 4 feet deep will hold the manure produced by two horses during about five months. About 2 cubic feet of box space should be allowed for each horse per day. The bin should be made of concrete or heavy plank. When the latter is used the cracks should be battened to prevent the escape of flies. The bin should have a concrete floor or it may be set in the ground several inches and the dirt closely banked around the outside. For the admission of the manure a good-sized door should be provided in either end of a large bin. A portion of the top should be made easily removable for convenience in emptying the box, or one entire end of the box may be hinged. On account of the danger of the door being left open through carelessness it is advisable to arrange a lift door which can be opened by placing the foot on a treadle as the manure is shoveled in. The door should be heavy enough to close automatically when the treadle is released. [Illustration: Fig. 4.--Working drawings of all-metal flytrap. The cones are removable and traps and cones can be telescoped for shipment. The trap may be made 18 inches in diameter at the top as well as at the bottom if traps are not to be shipped] [Illustration: Fig. 5.--Use of flytrap in connection with manure bin. A, block of wood set in ground to which lever raising door is hinged] A concrete pit set on a slope so that the manure may be dumped in from a wheelbarrow is convenient for dairy farms. For large stock farms it may be desirable to have a concrete pit so constructed as to permit of the manure being taken directly into it with a litter carrier and doors provided which are large enough to admit a wagon or manure spreader for the removal of the material. A manure bin with flytrap attached is shown in Figure 5.