Fungus Gnat

What do fungus gnats look like?

  • Fungus gnats are small flies, 1/32 to 7/16 inches long and although smaller, they are mosquito-like in appearance.
  • Typically, they are black, brown, or yellowish. Some species have dark colored wings, while some have spotted wings.

What are the habits of fungus gnats?

  • Fungus gnats are our most common commercial office-building pest in the office-setting.  This is a function of employees bringing plants to work.  
  • Larvae develop in a number of habitats—indoors and outdoors and primarily in moist organic matter.
  • Breeding sites include rotting wood, animal waste, old mulch, and over-watered indoor plants.
  • Fungus gnats are also commonly found within interior house plants.
  • Typically, the infestation will start in a single house or office building plant, and then females will identify and take up residence in neighboring plants within the space.

Damage From Fungus Gnats:

  • Although they pose no threat to humans, adults can easily become a nuisance indoors.
  • Fungus gnats are highly attracted to lights such as LED lighting created by computer screens—this creates an extreme annoyance within a work environment.
  • Larvae can damage plant roots, resulting in stunted plant growth.

What should I look for when dealing with fungus gnats? 

  • Immature stages appear as “glistening objects” within the top layer of moist soil in house plants. 
  • Resting adults are often found resting on plant vegetation—which often indicates and identifies breeding sites.
  • Moist organic matter, especially over-watered potted plants, which can easily breed large numbers of fungus gnats.

How can I control or get rid of fungus gnat infestations?

  • Allow soil to dry-out by reducing the level or frequency of watering.  Larvae cannot easily develop in drier soil.  
  • Infested plants can be taken outside to allow the sun to dry out top-most layer of soil.
  • Plants can be removed, repotted—to replace infested soil.
  • A one-inch layer of sand can be added to the top-most section of plant soil to create a deterrent for larval development to reduce breeding sites. 
  • Use clean, pasteurized soil to pot plants and do not bring infested soil indoors.
  • Pesticides are not a solution to these issues—only identification and environmental remediation as described will mitigate and reduce these pesky fungus gnats.

If you are tired of swatting at fungus gnats, call the entomologist-led professionals at Innotech Pest Management to schedule an appointment for one of our expert-trained service technicians to tailor a solution to your fungus gnat problems.