Because I still have scads of tomatoes ripening in the kitchen and the odd one decides not to ripen so much as to rot, we have pesky fruit flies. Correction. We had pesky fruit flies.
Now they reside at the bottom of this jar.
Recipe for fruit fly trap: 1-2 tablespoons water, 1-2 tablespoons vinegar, a few drops of dish soap.
That's it. The flies can hardly wait to come and drown themselves. I have tried it with balsamic vinegar and apple cider vinegar. The fruit flies love them both.