Getting Rid of Fungus Gnats on Plants
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Sticky traps are the number one gnat killer. Learn more below or get them here.
What are they?
They’re gross, let’s be honest. Most pests that infiltrate your houseplants and gardens are disrupting growth, gathering in numbers to "attack”, and just plain frustrating. In this case, we’re talking about the infamous fungus gnats.
The fungus gnat is similar to a fruit fly but prefers feeding on decaying organic matter (weak plants, for example). It’s smaller than a fruit fly with a little black body and soft wings. What’s interesting is that their life span is very short, with most of their time spent as larvae (egg) or pupa (puberty stage), and then one week as adults. A female adult gnat, however, will produce up to 300 eggs at one time. This is why they multiply so quickly and why it seems like they will never. go. away.
Where do fungus gnats come from?
I used to think certain bugs would simply “appear” out of nowhere like the big bang theory. But each little pest has to come from another pest, right? Here’s a twist for you - the origin of the fungus gnat is a mystery. Scientists have had a difficult time tracking it down. They can, however, identify that they are a part of the Mycetophilidae family - but keep in mind this family has around 3500 species…
According to bugs.com, the active season for fungus gnats is all four seasons, which means they can survive anywhere from freezing temperatures to sweaty summer days. Part of this is because fungus gnats love moisture. The first part of their identification, fungus, means “any of a group of spore-producing organisms feeding on organic matter, including molds, yeast, mushrooms, and toadstools.” Lovely, but this indicates a desire for wet, moldy environments, which is perfect for overwatered plants.
What’s happening with fungus gnats in soil?
If you see fungus gnats on plants, it means they’re also in the soil eating the plant’s nutrients. Fungus gnats flock to overwatered plants and settle into the environment. The adults then lay eggs in the soil. The larvae then go through insect puberty, as I call it, or pupa about two to three weeks later, and then they hatch. Once hatched, they feed on the nutrients and organic matter in the plant’s soil mixture. They can also chew at the plant’s roots and leaves close enough to their nesting zone.
Once your fungus gnats eat all the nutrients in the soil, the plant eventually dies. Don’t want this to happen? Contact us and we’ll treat it for you!
How to get rid of fungus gnats on plants
There are solutions! Literal, diluted solutions you can purchase or DIY and physical tools like sticky traps.
Sticky Traps
Gnats are attracted to the color yellow, and once they see the big yellow sign in their nesting environment, they fly to it and stick. This is one of the easiest methods to capture them. The one above is a bestseller and I highly recommend but I’ve also used this sticky trap and it works just as well!
Want to avoid harsh chemicals and bright yellow traps in your soil? Crop Control has natural ingredients and my favorite part is that not only will it treat gnats, but it also prevents mildew, mold, and other pests. It also has a slight minty smell which is a good cat deterrent.
Organic eco-oil and diluted vegetable oil are also two of the most useful products, confirmed by Sophia Kaplan and Lauren Camilleri of Plantopedia (one of my favorite plant books). These solutions, neem oil included, act as natural insecticides. Dilute it, put some in a spray bottle, and soak the pests. *Note: neem oil only works on insects that are actively chewing or sucking on the plant, not previously laid eggs.
Insecticidal Soap
This is one of the most common products used for killing pests. I personally use it on the more serious pest problems, and it does work for fungus gnats on plants. You’ll want to spray once a day for a few days until you don’t see any more gnats or pests.
Dry Out the Soil
There is too much moisture in the soil, that’s how the gnats got there, so try taking the plant out of the pot and loosening up the soil with a trowel until it dries out. I recommend using sticky traps as an addition to speed up the process by killing the flying gnats. Once it’s dry, put it back together in the pot.
Vinegar in a Bowl
The pungent smell of vinegar attracts gnats. This easy method, if your infestation isn’t too large, is to put vinegar in a small bowl, cover it with plastic wrap, and then poke a few holes in the top. The gnats will fly in and either drown (sorry little guys!) or have a difficult time finding their way out. Place the bowl near the plant so they will fly to it. Vinegar attracts fruit flies, as well.
Tips to avoid fungus gnats:
Thoroughly check your newly purchased plants - sometimes pests are lying dormant in the soil, waiting for moisture.
Regularly check your houseplants - the ones that have been around awhile are still susceptible!
Watch for weak or unhealthy plants - pests attack here first.
Don’t overwater! - keep your plants on a watering schedule here.
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Thanks for reading!
