Fungus Gnats

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Identification

  • Colour Grey to black
  • Size 3 - 4 mm
  • Also known as Diptera
  • Description Fungal gnats are tiny, delicate-looking insects belonging to the insect order Diptera. They are common pests of greenhouses and nurseries; however, they can occasionally be found in homes and commercial buildings where breeding conditions are available. Though mostly a nuisance pest, fungus gnats notoriously spread horticultural diseases that stunt the growth of various plant species. Adults are weak fliers with a short lifespan.

How to identify Fungus Gnats

Often mistaken for mosquitoes, fungus gnats are very small and range from 3 to 4 mm in length. These insects are grey to black in colour and have slender legs and segmented antennae that are longer than their heads, which help distinguish them from the closely related shore fly.

Fungus gnats are also easily identified by the Y-shaped vein in their wings.

Signs of an infestation

As fungus gnats are relatively tiny, detecting an infestation may be difficult. Adult fungus gnats are attracted to light and may congregate on windows or glass doors. Since the pests remain incapable of travelling great distances, such gatherings indicate a nearby infestation.

Fungus Gnats Removal

The first step to effective control of fungus gnats is to find breeding sources and eliminate them or to modify the conditions that encourage breeding. This will naturally eliminate fungal gnat populations. If adult population is high or infestations are heavy, treating with appropriately labelled insecticidal products will remedy the infestation. Many over-the-counter soil treatments and trapping methods are available to gardeners and homeowners. However, for large and challenging infestations, contacting a pest control professional is recommended for effective treatments that will successfully eliminate infestations and help prevent future re-infestations.

How to prevent Fungus Gnats from invading

The first step to effective control of fungus gnats is to find breeding sources and eliminate them or to modify the conditions that encourage breeding. This will naturally eliminate fungal gnat populations. If adult population is high or infestations are heavy, treating with appropriately labelled insecticidal products will remedy the infestation. Many over-the-counter soil treatments and trapping methods are available to gardeners and homeowners. However, for large and challenging infestations, contacting a pest control professional is recommended for effective treatments that will successfully eliminate infestations and help prevent future re-infestations.

Habitat, Diet, and Life Cycle

Habitat

Widely distributed, fungus gnats thrive particularly well in forested areas around the world. Given their poor flying abilities, they nest close to their breeding spots. Potential sites of infestation include the wet humus-rich soils or potting mix of potted plants indoors and outdoors, swamps, decaying vegetation, greenhouses, compost piles, and other sources of decaying organic matter.

Diet

Adult fungus gnats have a liquid diet and primarily consume water and flower nectar. During the larval stages, they feed on decaying organic matter and fungi.

Life Cycle

Although adult fungus gnats only live an average of 10 days, females lay approximately 150 eggs in their lifetime. They deposit the eggs directly onto food sources like damp plant soil. Hatching within a week, fungus gnat larvae feed for up to two weeks before pupating and adults emerge approximately a week later. Fungus gnats produce several generations each year and are most active during warmer weather. Depending on the temperature, they complete their life cycle in 21 to 40 days.

Commonly Asked Questions

Why do I have fungus gnats?

Adult fungus gnats are attracted to light and may congregate on windows or glass doors. Since the pests remain incapable of travelling great distances, such gatherings indicate a nearby infestation. As fungus gnats are relatively tiny, detecting an infestation may be difficult.

How worried should I be about fungus gnats?

During the larval stage of the life cycle, fungus gnats feed on plant roots. In doing so, they damage the roots and stunt the growth of the plants. Additionally, adults and larvae spread plant pathogens that cause collar rot, root rot, damping off, and wire stem diseases. Otherwise, adults are not capable of biting or harming humans nor do they cause any structural damage and are therefore considered to be nuisance pests.

Other pests related to Fungus Gnats

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