To save gnat-infested houseplants, you can also use honey. The sweet smell will attract the gnats onto your trap, and its sticky texture will prevent them from escaping.
- Attach a toothpick to one side of a bright-colored index card.
- Smear the other side of the card with a thin layer of honey.
- Put the card into the soil of your infested houseplant.
- Throw away the card once it fills up with dead gnats and replace it with a new one.
8. Vegetable Oil
You can use vegetable oil to trap and kill gnats that you see coming from the drain in your kitchen sink.
- Pour about ¼ cup of vegetable oil into your drain, and rub some oil around the edge of the drain.
- Use tape to close the holes of the drain.
- Leave it overnight.
- Remove the tape the next morning. You will notice gnats stuck on it.
- Repeat for a few more days.