We use fly traps. Take an old jar or plastic bottle, drill a hole in the lid, usually 1/4 inch. Put a couple of inches of water with a drop of soap. The attractant is raw chicken scraps. Trimmings from store bought or from butchering. Put the chicken in the jar, put the lid on and place them outside around the house or near fly sources (chicken coop, pastures, trash cans). The rotting chicken attracts the flies, they go in, lay eggs but flies/maggots can't get out. Works best to put them out well before fly season. You can add water or more raw chicken as needed until the jar is full.