Karo Syrup (corn syrup)
Liquid dish soap
small shallow dish
Instructions: Get a small, shallow dish. I use a baking ramekin because the surface is so smooth, sometimes the flies fall right in just perching on the edge! DIE, SUCKAS! Pour about 1/4-1/2 cup apple cider vinegar in the dish (should be about 1/2 inch deep). You can use other vinegars, but the smell of apple cider vinegar mimics the smell of fermenting fruit so well, it's got to be a fruit fly's fondest dream! Next pour about 1 teaspoon of Karo syrup into the ramekin. I don't measure it, but it eyeballs out to be a dollop the size of a quarter. Last pour in 1 teaspoon of liquid dish soap. Stir it up gently until it's evenly mixed; you don't want to make bubbles. Set it out on the counter a foot or two away from your fruit.
This works so well, that literally within 3-4 minutes of setting it out, the first fruit fly will bite the dust. I took this picture 20 minutes later:
As my flies converge, gorge and die, I leave the dish out--maybe a day--then I dump it out. If I continue to see fruit flies, I refill it. But as long as I don't leave out any cut fruit or leave fruit with bruises or wounds in the bowl, they usually stay away from then on.
Easy, huh? Try it and see how fast those suckers dive into your apple cider death trap!