Homemade fly traps aren't just economical, they also reduce the need for toxic chemicals. Making your own fly trap out of a milk jug is simple. The process can be completed in less than 10 minutes and at little cost. The most important step is creating a good attractant to put in the bottom of the trap. When making the trap, remember that flies tend to fly upward to escape, so don't worry about the size of the holes, as long as they are big enough to let the flies into the jug.
Rinse out the milk jug thoroughly.
Drill or punch a series of holes around the outside of the jug about 3 inches from the bottom. Make the holes large enough for the flies to easily crawl into the jug. Don't worry if the holes are a little too large. The flies are unlikely to escape.
Pour water into the jug until it is about 1/2-inch deep in the bottom.
Remove the lid and add material that is attractive to flies such as a small strip of meat, a small piece of cow manure, vegetable or fruit scraps or anything else with a strong odor that will attract flies.
Place the trap anywhere that flies are a problem.
Add water to the trap whenever it gets low. It's important to keep the bait wet so the smell continues to attract flies.
Empty the container when it becomes filled with flies up to the holes you punched out.
Reserve a little of the original bait from the bottom of the jug when emptying it, and add a little more water and bait to keep the fly trap working.