Add warm tap water to you bowl about half full.
Add dish soap; you want it to be the color of your dish soap.
Stir to dissolve the soap
Add apple cider vinegar. Until the color of the water is now the cot of the apple cider.
Stir and place where you Have the pesky gnats. You notice very quickly they are attracted to the apple vinegar and the soap make them to heavy to fly away and so the sink to the bottom.