How to Make Fruit Fly Trap Using Vinegar or Wine
A container such as a glass jar or disposable cup, plastic wrap, something to secure the wrap, toothpick, red wine, apple cider vinegar, basalmic vinegar, or other fermented vinegar or wine
Pour vinegar into container. NOTE: You can place a drop of soap in the vinegar to help break the surface tension.
Cover with plastic wrap and secure it to the container.
Use a toothpick to poke holes in the plastic wrap.
Place in problem areas.
Once you decide the jar is full enough either place it n the freezer for 20 minutes or submerge the jar in soapy water and let set for 10 minutes.