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How to Get Rid Of Fungus Gnats

fungus gnat on blade of grass

The world is not devoid of plant lovers. People adorn their gardens with a variety of plantations and some of them do not just stop there. They like to bring their green friends inside their houses as well. While this adds beauty to their residence and makes them happy, there is a problem that can arise in just such a scenario. Fungus gnats belonging to the families Sciaridae and Mycetophilidae are common plant pests that are liable to attack indoor plants especially in the presence of high moisture content and humidity. Any place their is a food source you can have a fungus gnat issue.

The first indication that these pests have invaded the privacy of your house is when the adult fungus gnats are witnessed flying around your precious houseplants. The adult stages are harmless in that they are non-biting. Still, they can turn into a flying nuisance. The real problem, however, is the larval stage of this insect that feeds in the soil and damages the tender plant roots.

Morphology of Fungus Gnats

The adult fungus gnats are grayish black, delicate in appearance, and are mosquito-like insects in morphology. These are 1/8 inches in length and have long legs. They fly with the aid of their one pair of wings. However, flying is not their best strength. They often come out from the potted plants more specifically during watering.

The larvae or maggots of this pest are ¼ inches long. Their head is shiny black but the rest of their body is elongated and whitish to transparent. They are most commonly found in rich, damp soils and feed on fungi, root hairs, and other such organic matter.

Life Cycle of a Fungus Gnat

The adult fungus gnats have a lifespan of a week during which they lay around 300 eggs. These eggs are laid in moist soil that is rich in nutrients. It takes theses tiny larvae around 4 to 6 days to emerge from the eggs. After that, they feed on the plant roots for a period of about 2 weeks. This pupal stage is 3 to 4 days after which the young adults are ready to leave their rich soil home and start the next generation. Depending on the temperature of their habitat, the entire lifecycle of the fungus gnats, from eggs to adult can be completed in only 3 to 4 weeks’ time.

Thanks to their short gestation period and proclivity, the potted plants are suitable for hosting each of their stage including egg, larvae, pupae, and adult. This is the reason why repeated applications of the treatments are required to get rid of the fungus gnats completely. This will ensure that there are no surviving eggs left behind.


When it comes to identifying if a fungus gnat has infected a plant, there are a few symptoms exhibited by the plants that indicate the presence of an infestation. These symptoms include loss of vigor, sudden wilting, yellowing, and poor growth. In case of severe attack, there is a high chance that a considerable portion of the infected plant might be lost.

Following species of plants are especially prone to injury by fungus gnats:

  • Geraniums

  • Carnations

  • African violets

  • Poinsettias

On the other hand, seedlings, young plants, and cuttings are more prone to be damaged by the larvae.

Controlling Fungus Gnats

When it comes to securing your houseplants from being infected by fungus gnats, following are some methods of controlling the pest:

  • You should always inspect the plants thoroughly before purchasing them to check for signs of pests. The best way to do this is to turn up the soil around the base of the plant and look for the presence of clear glossy larvae. In case of such presence, get rid of the plants.

  • Since these pests thrive in damp soil, refrain from overwatering the plants. This should be especially taken care of during the winters as plants use less quantity of water then.

  • Avoid using organic material that holds water such as peat when potting since that can encourage the egg laying process.

  • In case the plants have already been infested, do not water them until they are dried to around one to two inches of depth. This will not help in killing the larvae but it will also inhibit egg development as well as make the soils unattractive to egg-laying females.

  • Another great method to get rid of these flying pests is to make use of flying insect killer, which is an effective combination of cinnamon, peppermint, and sesame oil. This is a non-toxic tonic that will not only get rid of the fungus gnats but will also take care of several other insects.

  • Yellow Sticky traps can be used to capture huge amounts of egg laying adults since gnats are unusually attracted to yellow color. We recommend using Musca-Stik.

  • Eliminating the moisture source will help stop the breeding ground.  Use an adulticide contact aerosol to spray the plants and kill the annoying adult fungus gnats. Pyrid Aerosol is a natural Pyrethrin spray that the perfect solution for Fungal Gnats.

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Check out our Fungus Gnat FAQ for more helpful information on fungus gnats and how to eliminate them!

Are you dealing with gnats in your drains? See our guide to gnat control in drains.

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