Know Your Enemy: Fungus Gnats

A series of FAQs on pest management for indoor gardeners. This post focuses on how to get rid of fungus gnats.





What are Fungus Gnats


Fungus gnats are small bugs that look like small black flies. They are common pests for indoor gardeners and growers. A lot of times, they will infest your potted media and can be problems in greenhouses, nurseries, and other indoor growing setups.



What causes a Fungus Gnat breakout


Adult fungus gnats look for dark and damp soil to lay their eggs in. Gardens that have conditions that lead to dark or damp soil have a higher chance of a fungus gnat breakout.


Conditions leading to damp soil include:

  • not using enough light

  • not enough air circulation

  • overwatering the plants

The fungus gnats live for about 17 days, but can lay eggs that hatch every 3 days. In that sense, once you have a breakout, it can triple within a week. Infestations can get out of hand very quickly.


The gnats are common pests that can come in from outdoors, on other plants, in groceries, and more. They’ll find your garden and if the conditions are right, they’ll lay their eggs.



Damage caused by Fungus Gnat


Fungus Gnats eat fungus growing on plants and damp soil. As they eat they can transfer fungal infections to multiple plants in the same garden. Long term fungus gnat outbreaks can cause root rot in plants, which slowly starves the plant of water or nutrients. If left untreated multiple plants can die and your growing space can become inhabitable.



How to get rid of Fungus Gnats


Short term solution - Basic pest management, stop the fungus gnat cycle and get rid of the gnats currently alive in your garden. To stop the gnat cycle grab a BTI (Bacillus thuringiensis israelensis) product. We recommend the Mosquito Bits which takes care of Fungus Gnats and Mosquitoes but is safe for pets and everyone else. To get rid of the gnats currently buzzing around try your favorite brand of fly ribbon and hang a few strips around your garden. Rinse and repeat until sticky ribbon has a noticeable decrease in gnats.


Long term solution - The fungus gnats may return if conditions in your garden stay the same. Make sure you take the time to find out why your soil is staying damp. Find a way to dry your garden media and increase the light for your plants.







What to do if I have Fungus Gnats


Firstly, do not freak out! Getting an outbreak of fungus gnats is really common and happens to every indoor gardener at some point. It is also possible to reverse.


If you get an outbreak of fungus gnats, start fighting them immediately with immediate pest management techniques like fly ribbon or a BTI product. Then, stay consistent! Keep an eye on your garden and continue to manage the pests until you see the results you want. Finally, work in the long term to find ways to minimize dark and damp areas in your indoor garden.



Get rid of Fungus Gnats Checklist


Here's what you'll need to start your attack on the fungus gnats. Go manage those bad boys!


  • BTI product (Mosquito Bits for example)

  • Fly Ribbon

  • ~ Possibly more lights

  • ~ Possibly better draining soil

  • ~ Possibly fans for better air circulation




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