Noticing a bunch of tiny flies around your houseplants? Here are some tried and true methods on how to get rid of those pesky gnats in houseplants once and for all.
You’re sitting in your sunroom, and you notice annoying little flying insects buzzing about your houseplants. They are likely fungus gnats. While fungus gnats don’t pose any threat to you (aside from being super annoying), their larvae could harm your plants because they feed on the roots.
So how do you evict them from your plants and home? We have put together a guide showing you how to get rid of gnats in houseplants and then keep them away, once and for all.
How Water Helps Plants
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Noticing a bunch of tiny flies around your houseplants? Here are some tried and true methods on how to get rid of those pesky gnats in houseplants once and for all.
You’re sitting in your sunroom, and you notice annoying little flying insects buzzing about your houseplants. They are likely fungus gnats. While fungus gnats don’t pose any threat to you (aside from being super annoying), their larvae could harm your plants because they feed on the roots.
So how do you evict them from your plants and home? We have put together a guide showing you how to get rid of gnats in houseplants and then keep them away, once and for all.
What’s a Fungus Gnat?
Fungus gnats belong to the insect family Sciaridae. At only one-quarter of an inch in length, fungus gnats are often mistaken for fruit flies and drain flies.
But unlike fruit flies, fungus gnats eat decaying plant matter and mushrooms. So, it’s no wonder that you find them in jungles and forests where this food source is in abundance.
Unlike other insects, fungus gnats do not hibernate in the winter. As a result, they move indoors where the temperature and moisture levels are higher and can become a problem year-round.
In your house, they seek out overwatered plants, light, mold, and mildew. So, a sunroom full of plants with damp soil is practically inviting an invasion of this type of gnat.
How to Tell If You Have Fungus Gnats
Because fungus gnats are similar to fruit flies and are as small as drain flies, you’ll need to do some sleuthing to see if what you have are fungus gnats. An easy way to tell is by inspecting your plants. If you notice a large number of tiny flying insects hanging around and on your plants, they are most likely fungus gnats. Fruit flies hang around your kitchen where there is fruit, and drain flies will congregate around your drains. But to make sure, you should inspect the soil around your plant. Do you see any white specks? Those are probably fungus gnat larvae that will eventually turn into adult gnats that will lay more eggs in your plant’s soil. Does your plant look like it’s wilting? Or are the leaves turning yellow? If the answer to either of these questions is yes, there are probably fungus gnat larvae eating the plant’s roots. Your poor plant isn’t able to get all the nutrients it needs when its root system is being eaten for breakfast, lunch, and dinner. If you’re still not sure if it’s a fungus gnat invasion, you can try cutting up a raw potato and pushing the pieces into the soil of your house plant. Leave them there for a few days. If your plant is under attack from fungus gnats, you’ll see them feeding on the underside of the potato slices.
Ways to Combat Fungus Gnats
Now that you’ve determined that you have a fungus gnat problem, it’s time to learn how to get rid of gnats in houseplants. There are a few methods to choose from, so don’t worry if you try one, and it doesn’t work. Just move on to the next tactic, or try several at once.
Let Your Plants Dry Out
If your houseplants always have moist soil, that’s like putting a for sale sign out for fungus gnats to move into your plant’s soil and set up a home base. Moist soil is often full of algae and fungus, so try letting the soil of your plants dry out. A good rule of thumb is to let the top 2 inches of the soil dry out. That creates a less hospitable environment for the eggs to hatch into larvae.
Use a Hydrogen Peroxide and Water Mixture
A mixture of hydrogen peroxide and water is an easy and effective DIY remedy, as you likely have hydrogen peroxide in your home. Mix a 1:4 solution of hydrogen peroxide to water and pour it onto the dry soil. If you hear an effervescent sound, that’s perfectly normal. The hydrogen peroxide will kill the larvae and then break down in the soil without harming your plant.
Try Commercial Insecticides
Want those fungus gnats gone, fast? Using an insecticide is the way to go. Note that you will need two different forms of insecticide because what works on the adult gnats will not work on the larvae. The most effective pesticides are permethrin, cyfluthrin, bifenthrin, and lambda-cyhalothrin.Do not spray insecticide on the plant’s leaves or flowers but on the soil as that is where the gnats’ food source is. If you choose to use commercial insecticides, be sure to keep your plants away from children and pets. To be on the safe side, treat your plants outside, and leave them there if it’s warm enough.
Try an Organic Insecticide
If you’d rather not introduce commercial pesticides into your home, you can make an organic insecticide that uses neem oil as the base.
Neem oil comes from the fruit and seeds of the evergreen neem tree, which is indigenous to India and the surrounding areas. Neem oil works by disrupting the reproductive cycle of insects. It also repels insects and acts to reduce insect feeding.
Some companies manufacture neem oil-based insecticides, but you can also make your own. You’ll need a high-quality brand of cold-pressed neem oil, mild liquid soap (castile soap works well), water, and a bottle that’s big enough to hold a half gallon.
To make your solution, you need to fill your half-gallon container with water and add one teaspoon of neem oil and a half teaspoon of liquid soap to the water and mix well. If you use the metric system, that translates to 5 ml of neem oil, 2 ml of liquid soap, and 1 liter of water.
Pour the solution onto the soil and spray the leaves to take care of adult gnats on the plant. Discard any unused solution after a week because it will not be effective.
Note that if you’re pregnant or trying to get pregnant, neem oil also affects the human hormonal and reproductive system. You should take precautions.
Get Some Microscopic Roundworms
Also known as insect-parasitic nematodes, these microscopic roundworms are an effective, yet gruesome method to get rid of gnats.
You pour these roundworms onto the soil in a solution. Once they enter the gnats’ mouths and breathing pores, they release bacteria that eats the gnat from the inside out. It will take about four days for this method to work.
And don’t worry. These roundworms will not harm humans or animals.
Use Fly Tape or Yellow Flytrap Cards
All types of flies are attracted to the color yellow. Combine that with a sticky adhesive, and you can trap the gnats.
Flytrap cards will work better for fungus gnats because you can put the cards in the soil under the plant’s leaves. Fly tape needs to be hung from the ceiling, so it won’t be as effective.
This method works to reduce the number of adults from laying eggs that turn into larvae.
Transfer the Plant to New Soil
This is an excellent method for a stubborn infestation. All you need to do is get some fresh potting soil and repot the plant in a new container. You should rinse off the roots before repotting the plant, and be sure to throw out the infested soil.
Try sequestering the newly potted plant away from other plants that may have decaying plant matter to break the cycle.
How to Keep Fungus Gnats Away
Image by Shepherd Chabata from Pixabay
Now that you’ve learned how to get rid of gnats in houseplants, it’s time to learn how to keep them away.
Minimize Plant Debris
Like moist soil, plant debris is like a for sale sign for fungus gnats. The debris ends up decaying, and fungus gnats feast on decaying plant matter. So when you see leaves, flower petals, and stems in your plant’s soil, remove them as soon as you see them. And if you use potting soil that contains bark, try switching to a brand that doesn’t contain it. Bark retains moisture, which as you now know attracts fungus gnats.
Resist the Urge to Overwater Your Plants
It’s okay to let the soil in your houseplants dry out. There’s no need to keep it moist at all times. Of course, don’t let your plants dry out too much, but at least let the surface dry out before watering your plants. When in doubt, try sticking your finger into the soil to see how damp it is. You can also try adding perlite to the soil to help with drainage. And don’t let your plants sit in a drainage dish full of water. If there’s water in the dish, empty it about 30 minutes after you water it.
Conclusion
In this guide, we showed you how to get rid of gnats in houseplants as well as how to keep them from coming back. We want your house to be a gnat-free zone! We covered several tactics such as using insecticides, repotting your plants, and using fly traps. If one method doesn’t work, try another, or even try several tactics at the same time for the best results. And once they’re gone, you can keep them from coming back with proper plant maintenance and watering.
