Pour vinegar into small shallow bowl or ramekin, leaving about ½ inch space at top.
Stretch a piece of plastic wrap tightly across the top, making sure there are no gaps.
Insert toothpick (or icepick) through plastic wrap and swirl slightly to enlarge the hole abit.
Set on counter and watch the fruit flies gather for a pool party.
Notes
The vinegar loses its efficacy after a few days. Simple wash out the container, and repeat the above steps. If the flies are attracted to your trap, but aren't going it, chances are your holes are too small (or too large), increase the size of the holes. Or if too large, replace the plastic wrap and try again. Happy catching!