Gnat / Fruit Fly Trap (not edible)

Ingredients
1 glass jar
3-4 tablespoons apple cider vinegar
1-2 drops liquid dish soap
1 piece of white paper

Directions
Pour apple cider vinegar and 1-2 drops of dish soap into glass jar.
With the paper, make a cone with a 3/4-1" hole on the bottom. The cone should sit on the glass rim without the tip touching the vinegar.
Every day or two, switch out the vinegar.