Homemade Gnat TrapYou'll need a bright yellow index card (not sure why that one works, but the other colors don't seem to) anyway, Attach a straw, chopstick, or shish kebob stick to one side of the card with hot glue or tape. Then on the other side, smear bright yellow index cards with Vaseline or Honey. Insert the stick/straw end into soil of a houseplant & place it near areas where there are tons of Gnats.
How to make a wasp, hornet or yellow jacket trap from a 2 liter bottle. To keep the bees from getting in here (and keep them doing their good job!) just add apple cider vinegar. Bees don't like the sour, but wasps do.