DeVries adds a fruit fly's life cycle is finished in a week or two, thus “the population collapses quickly.”
DeVries: No need for pesticide. That's something to avoid while cooking. It's also useless and won't address the situation.
DeVries offers a fly swatter or a vacuum you can empty outdoors to kill flying pests.
Add a few drops of dishwashing detergent to half an inch of fruit juice, vinegar, apple cider, or wine.
Cover with plastic wrap and poke holes in it.
The bait attracts the flies, but the soap breaks the surface tension of the water, trapping them.