A fungus knat crawling on a leaf - Keep fungus knats out of your home with Kona Coast Pest Control in Kailua Kona

Fungus Gnat

Actual Size: 1/10 to ⅛”

Characteristics: Small, dark in color; similar in appearance to mosquitoes.

Legs: 6

Antennae: Yes

Wings: Yes

Habitat: Attracted to moisture; found in high moisture areas in the home including, kitchens, bathrooms, laundry rooms, and crawl spaces.


  • Found worldwide and can be common pests in both indoor and outdoor settings.
  • Weak fliers that are often seen hovering around potted plants and windows. 
  • Thrive in areas with high moisture, such as overwatered houseplants, greenhouses, and compost bins.
  • Their larvae cause damage as they feed on fungi, decaying organic matter, and the roots of plants.
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Fungus Gnats in Kailua Kona

Fungus gnats are small insects with a delicate appearance, long wings, and spindly legs. They can occasionally become a nuisance in both residential and commercial buildings. This is particularly evident in environments where ferns and other house plants with organic-rich soil serve as breeding grounds. The larvae of these insects primarily feed on fungi and organic matter in the soil but can also pose a problem by chewing on roots. The issue becomes more pronounced in settings such as greenhouses, nurseries, and interior plantscapes. Adults are drawn to lights and are often initially seen near windows or light fixtures.

Fungus Gnat Habitat

In outdoor settings, fungus gnats are drawn to moisture, and issues may arise in regions where the landscape has been excessively watered or in low-lying areas that retain excessive wetness after heavy rainfall. These insects are attracted to light and are often seen hovering near windows. Unlike house flies, fungus gnats are characterized by weak flying abilities, typically remaining close to potted plants. They can also be present in areas with high moisture levels within the home, such as kitchens, bathrooms, laundry rooms, and crawl spaces. This adaptability to various environments emphasizes the importance of managing moisture to mitigate the likelihood of fungus gnat infestations both inside and outside the home.

Fungus Gnat Behaviors, Threats, or Dangers

Adult fungus gnats, while not posing a direct threat to humans or plants, are primarily regarded as a nuisance due to their hovering behavior. The true concern lies with the larvae of fungus gnats, as they can inflict substantial harm to plant roots. Particularly in cases of abundant populations, the larvae may cause significant damage and hinder the growth of plants, especially in seedlings and young plants. Instances of notable root damage and even plant fatalities have been documented in interior plantscapes and houseplants, particularly when thriving in moist, organically rich soil. Wilting houseplants may not be a sign of water scarcity but rather root damage by fungus gnat larvae. If you’re experiencing a fungus gnat issue, contact your local fly control professional.