I know how. Didn't read the whole thread so IDK if anyone said it yet BUT....
You get a glass and put either some sugar water or some wine or some liquor in th bottom of it. You don't have to fill it up..just like an inch or so. You cover it with tin foil and stick a straw down thru it. You have to tape it so that the straw doesn't get into the liquid and make sure the only hole is the straw. This way the files fly into the straw to get the liquid, but they are too dumb to find their way out. Do like 2 or 3 of them around the house and don't leave anything to drink or fruit out for a few days.