Fungus gnats are small flies that infest soil, potting mix, other container media, and other sources of organic decomposition. They are a common pest of plants grown indoors, especially where humidity and moisture are high. Adult fungus gnats are not strong fliers and emerge from potted plants, especially when watering. They are delicate, grayish-black, mosquito-like flies about 1/8 inch long with long legs and one pair of clear wings. Larvae or maggots are about a 1/4 inch in size and have a shiny black head and an elongated, whitish transparent body.

Not sure if you have a fungus gnat problem? Or maybe you want to learn more about how fungus gnats control works. Check out the following information to clarify some questions you may have.

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Should I be concerned about fungus gnats?

Mature adult fungus gnats are more of a nuisance than anything; they do not actively harm plants or people. They become a problem when the population starts to increase sine their larvae will need to feed. Their primary food sources are fungi, plant roots, and other organic matter in soil; causing damage to your plants. This is especially bad for young plants, such as seedlings, which have only a few delicate roots. If infestations are large enough, the pests can stunt foliage growth and even kill houseplants.

Fungus gnat damage will appear similar to that of any other root-related issue, such as root rot. Lower leaves may turn yellow and drop and the plant’s growth may slow down or stop completely. If infestations are large enough, the pests can stunt foliage growth and even kill houseplants.

Signs of a fungus gnats’ infestation

Fungus gnats’ life cycle can go from 7 to 12 days. In this period of time the females can lay up to 300 eggs, they lay them on the soil, where there is adequate moisture. Once they hatch, they will start to feed on plant roots and fungi near the surface of the soil. They will grow to about 8 mm long. They will then pupate and the adult gnat will emerge to take flight. The following are clear indicators of a fungus gnat infestation in your property:

  • Identify the insect; adult gnats are small nuts relatively easy to identify.
  • Larvae in the soil; cream-colored larvae, typically stay hidden in the top 2 to 3 inches of soil.
  • Examine plants; look over your plants to see if they have fungal gnats. It is common for these pests to consume younger plants and affected plants will show signs of wilting or stunted growth.

Why do I have fungus gnats?

Most people notice that they have fungus gnats in their homes because these tiny bugs will often try to fly into a person’s face. They can be especially irritating to someone who sits at a desk near the origination of the infestation. They often travel indoors on potted plants or cut garden flowers. Once they get inside the population can quickly grow out of hand. The following are some reasons why fungus gnats may be attracted to your property:

  • Moisture; fungus gnats love to live and breed in the moist soil of overwatered houseplants, in containers or pot liners, or around areas with standing water.
  • Decaying organic matter; these tiny insects are attracted to moist, decaying, organic material, such as dead leaves, leaf husks, fungus, or any other organic debris on top of the soil’s surface or down inside the pots and liners since they feed on them.
  • Light source; fungus gnats typically swarm around windows, lamps, and other light fixtures.
  • Carbon dioxide; just like most flies, fungus gnats love CO2, which is why they like to hover around your mouth and nose.

Can I get rid of fungus gnats myself?

There are multiple ways to get rid of gnats using commercial products and natural non-toxic home remedies. Getting rid of this pest is all about consistency. If the infestation is not bad you can try the following to try to get rid of them:

  • Dry out the soil; for an over-watered plant, you must begin drying out the soil as soon as possible. Overwatered plants get root rot, and rotten roots are a perfect food source for fungus gnats.
  • Remove dead leaves; if there are dead leaves or any other kind of debris in the soil or inside the liners or containers of your plants, it must be removed.
  • Steel wool; place a thin layer of steel wool on top of the soil of your potted plants and leave it there for at least 4 weeks. Any larvae trying to fly out will literally get shredded to pieces, and adults flying in to lay their eggs will also die.
  • Remove the top layer of the soil; once you believe all the larvae are dead, replace the top layer of the soil with sand.
  • Cider-vinegar traps; place a shallow container with a small amount of apple cider vinegar, water, and a little liquid dish soap near the base of the affected plant or, ideally, inside the pot on top of the soil.
  • Sticky card traps; these traps are yellow note cards covered in a sticky adhesive. They are most effective when cut into small squares and placed directly on top of the soil or attached to skewers just above the soil.
  • Potato slices; place potato slices on the surface of your potting soil. Fungus gnat larvae will swarm onto the slices after about four hours, and you can then dispose of them. Do this repeatedly until you think all the larvae are gone.
  • 3% hydrogen peroxide; once your soil is dry, water your plant with a mixture of 1 part hydrogen peroxide and 3 parts water. You must dilute the hydrogen peroxide and only use the 3% hydrogen peroxide you find at the drugstore and nothing higher; this will kill the larvae.

Tips to prevent fungus gnats

Use the following tips in order to prevent fungus gnats from damaging your plants and infesting your home:

  • Don’t overwater your plants; give your plants the proper amount of water according to their species.
  • Keep the soil dry; allow your houseplants to dry out a bit between waterings. Let the top inch or two of the soil dry out before watering again.
  • Keep your plants clean; remove dead leaves, stems, debris, etc.
  • Soil choice and modifications; when potting up a new houseplant, use a reputable quality bagged potting soil. One that has been pasteurized or sterilized shouldn’t have live eggs, larvae, or flies in it.
  • Use sand; fill the top of your pot with 1/2 inch of sand. Water drains quickly in the sand and will keep the top layer dry, preventing gnats from laying their eggs.
  • Don’t use compost, peat moss, or mulch: These materials retain moisture and contain decaying material that fungus gnats are attracted to.

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    Our fungus gnat control process typically consists of the following stages:

    • Confirm or discard the existence of fungus gnats in your home through an inspection
    • Identify the factors that may be causing and contributing to the infestation.
    • Offer pest control programs to get the problem under control.
    • Treat the existing population and prevent future infestations.

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