fill a small bowl with a few tablespoons of vinegar. Then,put a piece of very ripe or rotting fruit into the vinegar. Cover the bowl very tightly with a sheet of plastic wrap and poke a few very small holes in the wrap with a fork. If all goes according to plan,the flies will enter the trap through the holes but will be unable to fly back out. This trap will catch all of the remaining fruit flies. You can either kill these flies or release them outdoors.