Fungus Gnat


Actual Size: 1/10 to ⅛”

Characteristics: Gray to black or orange-yellow with smoke-colored wings.

Legs: 6

Antennae: Yes

Wings: Yes

Habitat: Needs moisture to survive and are primarily found in damp areas with easy access to organic matter.


  • Weak fliers that thrive in damp conditions.
  • Fungus gnats often remain near potted plants when indoors.
  • Larvae cause all the damage as they feed on plant roots, stunting plant growth.

Fungus Gnats in San Angelo

Fungus gnats are small insects with a delicate appearance, characterized by long wings and spindly legs. At times, they can become a nuisance in residential and commercial buildings, particularly when ferns and other houseplants with organic-rich soil serve as breeding sources. The larvae of fungus gnats primarily feed on fungi and organic matter present in the soil. However, they can also chew on plant roots, making them problematic in greenhouses, nurseries, and indoor plantscapes.

Adult fungus gnats are attracted to lights, and they are often first noticed near windows or light fixtures. Their attraction to light can lead them inside buildings, where they become an annoyance for occupants. Monitoring and managing fungus gnats are important steps in maintaining healthy indoor plants and preventing potential issues caused by their presence.

Fungus Gnat Habitat

In outdoor settings, fungus gnats are drawn to moisture, and issues may arise in areas where the landscape has been excessively watered or in low-lying regions that retain water after heavy rainfall. Inside buildings, fungus gnats are attracted to light and can be observed hovering around windows. However, in comparison to house flies, fungus gnats are not strong flyers and tend to stay close to potted plants. Additionally, they may be found in areas with high moisture levels indoors, such as kitchens, bathrooms, laundry rooms, and crawl spaces. Monitoring and addressing moisture levels in these areas are essential steps in managing fungus gnat populations and reducing their presence indoors.

Fungus Gnat Behaviors, Threats, or Dangers

Adult fungus gnats do not bite or harm plants; their presence is mainly considered a nuisance to people. The real culprits causing damage are the fungus gnat larvae. When present in large numbers, these larvae can harm plant roots and impede plant growth, especially in seedlings and young plants. In interior plantscapes and houseplants, significant root damage and even plant death have been observed when the larvae populations were high, particularly in soil rich in organic matter and moisture.

Therefore, if you notice a houseplant wilting, it may not necessarily indicate a lack of water; it could be a sign of root damage caused by fungus gnat larvae. Monitoring and addressing the presence of these larvae in plant soil are essential for maintaining healthy plants and preventing potential damage. If you’re experiencing a fungus gnat issue, contact your local fly control professional.