How to Eliminate Fungus Gnats

Overview

Fungus gnats are small flies that thrive in moist soil, especially the soil in household potted plants. These flies actually do not fly well and tend not to venture far from their houseplant habitat. The larvae of the fungus gnat do the greatest damage. According to the University of California Integrated Pest Management (UC IPM) website, the larvae eat not only the rotting debris found in the soil, but also the roots of the plant. This can slow the plant's growth or even kill it.

Step 1

Water your plant only as much as necessary. UC IPM recommends allowing the top layer of the soil to dry completely before the next watering. Do not over water your plant.

Step 2

Remove all debris from the soil such as fallen flowers and dead leaves. This removes a food source for the gnats.

Step 3

Do not use manure or other organic fertilizers or mulch in household plant pots. These attract fungus gnats.

Step 4

Spray a non-toxic insecticide on the houseplant and soil to kill the adult gnats. You can make your own insecticide by mixing several drops of dish soap with a spray bottle full of water. Then lightly spray the plant.

Step 5

Take the trash out regularly and do not allow fruit to rot inside the house. These are all places that fungus gnats breed, eventually moving to household plants.

Step 6

Poke several small holes into a plastic bottle and fill it halfway with vinegar. Set this vinegar trap near infested houseplants. The adult gnats will become trapped in the bottle and you may then discard them.

Things You'll Need

  • Debris-free soil
  • Non-toxic insecticide
  • Plastic bottle
  • Vinegar

References

  • Caring for House Plants: Gnats
  • UC IPM Online: Fungus Gnats
  • UC Davis: Soap Sprays as Insecticides
Keywords: rid fungus gnats, fungus gnat investation, houseplant bugs

About this Author

Lynn Anders has more than 15 years of professional experience working with animals as a zookeeper and wildlife educator, and in pet rescue. Freelance writing since 2007, her work has appeared on websites such as Modern Mom and Trails, and includes pet-related topics, environmental issues and parenting matters. She has a Bachelor of Arts in environmental studies from Cal State University-Sacramento, and minored in biology.

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