The supplies you will need to capture fruit flies. Apple cider vinegar,liquid dish soap, a jar, piece of paper made into a funnel shape, water is in my tap.
Add the ounce or so of apple cider vinegar to your jar along with a drop of the liquid dish detergent.
Like so, give the soap a stir, it helps break the surface tension of the vinegar.
Take the paper and create a funnel shape and insert it into the mouth of the jar. You want the bottom of the funnel to rest just above the vinegar, and have no gaps around the rim of the jar.
Funnel just above the vinegar,add about 25% water if you need to raise the level to reach the funnel. The surface tension is broken by the soap. The flies will sink instead of sitting on the surface
Set the jar up in the area where the fruit flies have taken up residence. In my case near my indoor compost canister.
The fruit flies are attracted to the vinegar, they fly down into the funnel and are unable to fly back out again. Little buggers drown I'm afraid.
After a few hours, the first victims have been claimed.
This works quickly, and involves no pesticides, I will change it after about two weeks, or until the sight of their little corpses weigh on my conscience. I dump the contents into my garden composter.
Hope my fruit fly killing machine design makes sense and is helpful in your quest to rid yourself of this scourge.