All you need is:
1/4 cup vinegar
1/4 cup sugar
water
plastic container with secure lid
Put first two ingredients in and put enough water to fill container about half full. Punch a few holes in the lid (big enough that the flies can get in!) Run a string through 2 of the holes in the lid. Replace lid and hang in stable. Works great!
Thanks to Kim for this one.

can we get a photo of any kind?