网上找到的，我自己家里就用红糖水，效果很好，放虫子出没地方

Fill a microwave-safe bowl with apple cider vinegar and a few drops of dish soap. Microwave the bowl so the mixture becomes even more aromatic. Leave the bowl out uncovered as fruit fly bait. The soap will reduce the surface tension, causing any fruit fly that lands on the surface to drown.