Fungus Gnats

Protect Your Home or Business From Fungus Gnats

Also known as manure flies, fungus gnats are attracted to fungi and organic matter. They’re small and resemble mosquitoes, though the adults don’t bite.

It’s common to spot these pests in greenhouses and nurseries as well as hovering around potted plants in homes.

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Appearance & Identification

As fungus gnats rarely grow larger than 1/2" inch in length, it's hard to see their unique features with the naked eye.

Their slender legs, long antennae, and distinctive Y-shaped wing vein are only noticeable when the insects are magnified.


To be near their food source, fungus gnat larvae primarily live in soil. Adults are drawn to light, so they're often found near windows.

However, since they are weak fliers, these insects are mostly seen in close proximity to house plants. They are found nationwide.


The fungus gnat diet consists of:

  • Fungi
  • Algae
  • Other organic plant matter


Adult fungus gnats lay their eggs directly into a food source. Since larvae must feed to grow, the pests do the most damage in this stage.

It takes about two to three weeks for these insects to reach adulthood.

Problems Caused by Fungus Gnats

Larvae don't limit themselves to consuming the fungi found in damp earth. They also eat roots. When they're present in large numbers, the pests can stunt the growth of plants as they feed. Significant fungus gnat damage to roots may even cause plant death.

Signs of Infestation

Homeowners might have a fungus gnat infestation if they notice:

  • Small flies gathering on windowsills or around houseplants.
  • Foliage that suddenly starts to wilt.
  • Excessively damp dirt in pots.

Need Help with Pests?
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The best way to prevent fungus gnats is to carefully monitor the amount of water given to potted plants. Additionally, make sure there's proper drainage for individual plants as well as around the house.

Unfortunately, it's hard to check fertilizer and soil for fungus gnats before purchasing, and homeowners may end up with an infestation despite their care. At the first sign of the pests, contact Waltham Services for removal.