Fruit Fly Catcher Solution
1 T vinegar
1-1/2 t white sugar
drop of liquid dish soap
2 cups (1 pt) of water
Mix all 4 ingredient in a 2-cup measuring cup, a bowl, or a pint jar. Mix well. Using small pottery cups, fill each about 1/2" deep with the solution. NOTE: clear glass containers don't seem to work as well in attracting the insects. I use little oriental tea cups which have no handles. I pour any remaining solution into a pint canning jar and cover it, keeping it in the refrigerator until I need to clean out and replenish the little cups.
Position the uncovered filled cups where you see the fruit flies most often, like on the kitchen counter where you cut fresh produce or near the bowl of bananas. Placing them under a light source seems to help attract the bugs. After a few days check the cups and you'll likely see signs of success!
I've also used this solution to re-fill some commercial apple-shaped fruit fly catchers after the liquid they come with has expired, and it seems to catch more. 'Hope it works for you too!