As the season warms, the fruit in my kitchen becomes a fertile ground for fruit flies. Their quantity and tenacity frustrated me until I learned of a simple and effective trap.
Partially fill a glass with a sweet fruit juice like grape and add a drop or two of dish soap. Set the trap near your fruit and it should take care of the problem. See the image below.
The sweet juice attracts the flies who climb on in for a meal. The soap breaks the surface tension of the juice and sucks the flies into their demise.
It provides great control, is easily made and pretty safe around children and pets.