Fungus gnats, also known as vinegar flies, come inside in any season, but they really proliferate during the summer and winter. They tend to come indoors on house plants that have been outside during warm weather. The larva lives in plant soil and hatches to suck on your plants. Adult gnats are especially attracted to vinegar, so vinegar is a safe and inexpensive way to stop a fungus gnat attack on house plants.
Fungus gnats love to eat fermented foods. Fill a jar with vinegar. Use a pin to poke about 5 holes in the lid. Fungus gnats will flock to the jar and down the holes to get to the vinegar, but they can not get out.
Vinegar and Sticky Food
After setting out a jar of vinegar, add peanut butter or honey to the under side of the lid that is poked with small holes. Gnats will not be able to fly out of the jar. The sticky peanut butter or honey will catch them as they try to escape if the tiny holes do not stop them.
Vinegar and Soap
A cup of apple cider vinegar mixed with 1/4 cup of dish soap placed around where the gnats are the most is a good trap. Place four to five glasses in different rooms and under afflicted plants. The gnats will flock to the vinegar, get stuck in the soap and be unable to fly out.