I had trouble with the pesky critters for about 2 weeks before I finally decided I had to do something about it. I had already removed fruit from my counters, but they were still there. I did some online research and found that fruit flies can live off of organic matter stuck in the sink drains or on damp washcloths or towels in your kitchen. I quickly removed baby bibs and wash cloths and cleaned my drain with baking soda and vinegar. Then I made a trap!
Here's how to make your trap: find a small disposable container. Put in some cider vinegar to bait the trap. Poke several holes in the top. I used a knife point and twisted it. Before long, the fruit flies were drawn into the trap, and several got stuck in the vinegar. They were ALL gone within 3 days. Then just throw the whole trap away!