Fungus Gnats

Last Updated: November 28, 2018

Definition - What does Fungus Gnats mean?

Fungus gnats are plant pests that can be found in sewer areas, household drains, and wet plant soil. They are the most common pests of plants that are grown indoors, especially where moisture and humidity are high.

Fungus gnats lay eggs in moist soil, and they can be heavily attracted to plants that have been overwatered. Young fungus gnat larvae, born into the moist soil, feed on the fine roots of plants.

MaximumYield explains Fungus Gnats

Fungus gnat infestations often occur and thrive in damp, decaying vegetation, fungi, and algae. They are not only problematic in houseplants, but can cause issues in greenhouses and nurseries. Once fungus gnats have access to moist plant soil, they will infest soil and container media by laying eggs. When the eggs hatch, the fungus gnat larvae will feed on organic matter in the soil. This organic matter includes the feeder roots and root hairs of plants. Although gnat larvae do not generally damage plants, they will turn to plant roots when their preferred food choice runs out.

When fungus gnat larvae damage plants, they will cause stunted plant growth, yellow and dying leaves, and depleted root systems. Additionally, they can harm seedlings and cuttings. Fungus gnats, although they do not carry human pathogens, can transmit plant fungal diseases such as black root rot and pythium blight. However, there are several different methods that can be used by gardeners and growers to treat and prevent an infestation of fungus gnats.

The first and foremost method of prevention is to avoid overwatering plants, particularly houseplants. Removal of dead plant material and debris can take away a possible fungus gnat food source. Before bringing a plant indoors they should be checked for possible fungus gnat infestations. In larger horticultural settings such as greenhouses, preventative measure such as adding natural fungus gnat predators to plant soil can be an effective method. However, if an infestation is too large, chemical measures may be necessary to reduce and control populations.

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