Fungus gnats are small, dark-colored flies that can become a nuisance pest, even in homes without indoor plants The larvae feed on fungi and organic matter in potting soil, compost piles, and other damp areas While fungus gnats don’t bite humans, their presence can be annoying, and their larvae can damage plant roots.
If you notice fungus gnats buzzing around your house but don’t have any plants for them to infest, you may be wondering where they are coming from and how to get rid of them. The good news is there are several effective methods to eliminate fungus gnats, even if you don’t have houseplants.
Where Do Fungus Gnats Come From?
Fungus gnats enter homes in a few common ways
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Potting soil or compost: Bagged soil or compost can contain fungus gnat eggs or larvae. If you’ve recently repotted plants or used compost for gardening, this may have introduced the gnats.
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Through drains or pipes: Fungus gnats are attracted to moist environments. They can breed in drains, sinks, or little-used pipes.
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From neighbors: If your neighbors have an infestation, the adult gnats can fly between homes.
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New plants: Houseplants purchased from a nursery may already have fungus gnats. Quarantining new plants can prevent spreading.
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Outdoor habitats: Gardens, compost piles, and mulch beds can harbor fungus gnats. Adults may fly indoors through open windows or doors.
How to Get Rid of Fungus Gnats Without Plants
Here are some of the most effective methods to eliminate fungus gnats in a home without indoor plants:
Remove Breeding Sites
Fungus gnat larvae need moist organic matter to survive. Removing these breeding areas will help control the infestation.
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Clean out sink and bathtub drains, garbage disposals, and overflow holes. Scrub away grime and residue with a brush.
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Pour boiling water down drains and toilets to kill larvae hiding in pipes.
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Clean trash and recycling bins that may contain moisture and debris.
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Eliminate compost piles or food waste bins indoors. Compost outdoors in a sealed bin.
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Fix any leaky pipes, faucets, or other sources of moisture.
Use Traps
Traps can catch adult fungus gnats and prevent females from laying more eggs. Try these DIY traps:
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Apple cider vinegar traps: Fill a shallow bowl with apple cider vinegar, a few drops of dish soap, and water. The gnats are attracted to the vinegar but get trapped in the soapy water.
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Wine bottle traps: Cut the funnel-shaped top off a clear plastic soda or water bottle. Fill it 1⁄3 with cheap red wine. The gnats fly in but can’t escape.
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Yellow sticky traps: The gnats are attracted to the color yellow. Place sticky traps horizontally near fungus gnat activity.
Apply Natural Pesticides
Natural insecticides can kill fungus gnat larvae in infested areas:
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Bacillus thuringiensis israelensis (Bti): This bacteria occurs naturally in soil. When ingested by fungus gnat larvae, it kills them within 24-48 hours. Apply as a drench to potting soil.
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Diatomaceous earth: The sharp edges of this powder scratch the insects’ exoskeletons, causing dehydration and death. Sprinkle a fine layer in infested areas.
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Neem oil: Extracted from the neem tree, this oil disrupts the growth and reproduction of insects. Mix with water and spray onto surfaces where gnats congregate.
Use Beneficial Nematodes
Microscopic nematodes are deadly parasites to fungus gnat larvae. They occur naturally in soil but can also be purchased. Follow product instructions for application. The nematodes will kill larvae but are safe for people, plants, and pets.
Maintain Dry Conditions
Without moisture, fungus gnats can’t complete their lifecycle. Eliminate damp areas and fix leaks to remove their breeding grounds. Run fans, dehumidifiers, and air conditioning to keep things dry.
Prevent Fungus Gnats From Returning
Once you get rid of your current fungus gnat infestation, take these steps to prevent the pests from coming back:
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Inspect new plants closely before bringing them home. Quarantine them away from other plants.
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Allow potting soil to dry out between waterings. Fungus gnats prefer consistently moist soil.
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Avoid composting food scraps indoors. Compost outdoors in a sealed bin.
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Clean up decaying plant matter and leaf litter in your yard.
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Use yellow sticky traps continuously to monitor for fungus gnats.
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Apply beneficial nematodes or Bti preventatively to potted plants.
With diligence and persistence, you can eradicate fungus gnats from your home, even without indoor plants for them to infest. Removing breeding sites, trapping adults, and applying pesticides will help eliminate these annoying flies. And prevention is key to ensuring the gnats don’t return once you’ve got them under control.
How to Get Rid of Fungus Gnats
I tried several methods to kill my herd of intruders before I finally found a solution. But first, here are some frequently-mentioned remedies that didnt work for me or were just too inconvenient to try:
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Apple Cider Vinegar
Every time I’ve looked up a method to get rid of fungus gnats or fruit flies, the mixture of apple cider vinegar, dish soap, and water is always at the top of the list – and it has NEVER worked for me. This time was no exception.
It seems like the smell is just as obnoxious to the bugs as it is to my nose, and no one wants to go near the stuff.
Neem Oil & Other Sprays
Neem oil is a naturally occurring pesticide and came up frequently as an option to rid my life of fungus gnats, so I gave it a whirl. But I had some issues with it.
First of all, the suggested application was to drench my plants in neem oil – including the tops AND bottoms of leaves as well as the stems. This proved to be a really messy endeavor, especially when dealing with an oily substance.
On top of that, although the smell isn’t super strong, I definitely wasn’t a fan. Needless to say, this method didn’t work either.
I also tried other sprays that claimed to kill fungus gnats but to no avail.
Waiting Longer Between Waterings
Because fungus gnats thrive off the decaying material in soil, which is exacerbated by dampness, the idea behind this method makes sense. This seemed to work in the short term, but I ended up needing to water my plants before they died and the gnat problem picked right back up.
Drench in Water
I realize this remedy seems counterintuitive to the recommendation above. Let me explain.
The idea isn’t to just water your plants into oblivion, but rather to either put them in the shower and give them a good spray or dunk them in a bath to wash away the pests.
The problem here is that A) not all of my pots have drainage holes or nursery pots (something I’m working on switching out, don’t @ me), and B) it’s unlikely that this would wash ALL the larvae away. I didn’t even bother giving this idea a try.
Repotting
I have A LOT of plants, so it would have been wildly inconvenient to repot them all, but if you only have a couple this would be a viable option. Just make sure you throw out the old soil and maybe give your plant a good rinse before repotting.
What Are Fungus Gnats?
Fungus gnats are tiny flies that survive off the fungus in your plant soil. Theyre dark gray in color and only about 1/8″ long. They dont bite and are harmless to humans.
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FAQ
How to get rid of fungus gnats without killing plants?
- Fungus gnats thrive in moist soil. Allow the top inch or two of your soil to dry out between waterings.
- Consider using a soil moisture monitor to avoid overwatering.
- Ensure your pots have good drainage to prevent water from stagnating.
How do you find the source of fungus gnats?
The presence of fungus gnats is often an indication of overwatering. Look for adult fungus gnats resting on plants, soil, windows, or walls to identify the source of your infestation. If you do have an infestation, you can use yellow sticky traps to catch adults.
What scent keeps fungus gnats away?
Peppermint, lemon, eucalyptus, vanilla, and lavender essential oils all have scents that gnats dislike. Place a few drops of any of these essential oils on cotton balls and set around entryways to your home or areas where gnats are a problem.
Will fungus gnats go away if I stop watering?
Gnats will not survive in soil that gets a proper dry down (and bonus because plants LOVE it, too). Dry your plant until the soil is pretty much completely dry and then water it slowly until you get about 30% runoff. Repeat for the plants life. You will be VERY surprised how much better your plants look by doing this.
How do I get rid of fungus gnats in my garden?
To get rid of fungus gnats in your garden, you can try the following remedies: 1. Adjust the amount of water you use. 2. Cover any bare soil. 3. Use sticky fly traps around infested plants. 4. Place homemade vinegar traps around your plants. 5. Buy (or make) insecticidal soap to use as a natural pest spray. 6. Use neem oil spray. 7. Sprinkle Mosquito Bits over affected soil. 8. Use hydrogen peroxide as a soil drench.
How do you get rid of gnats in a houseplant?
To get rid of gnats in a houseplant, check that the potting mix doesn’t have larvae by carefully inspecting the bag for signs of fungus gnats. Tap the pot a few times when purchasing new plants to dislodge any gnats. A treatment outdoors will also help prevent gnats from moving into other plants around your home or greenhouse.
Do you have fungus gnats in your houseplants?
Yes, you likely have fungus gnats in the soil of your houseplants. If left unchecked, they’ll multiply and infest your other plants too. Here are 11 tested-and-true remedies to eliminate them.
How do you eliminate gnats in soil?
To get rid of gnats in soil, you can use several methods. Neem oil, hydrogen peroxide soil drenches, beneficial nematodes, and pyrethrins are all effective in killing gnats, their eggs, and larvae. Additionally, yellow sticky traps can help catch and kill flying gnats. Fungus gnats belong to the superfamily Sciaroidea, and their larvae feed on the fungus growing in soil.
What can prevent fungus gnat infestations?
Dry soil would prevent infestations, but our plants do need water. Okay, so now you know that fungus gnats love damp soil. Use a chopstick to carefully poke into the medium, moving it around a little to create air pockets and allow water to penetrate deeply but drain easily.
How to catch fungus gnats?
Fungus gnats deposit their eggs in the soil. Therefore, traps should be placed on the soil’s surface to catch the adults before they lay eggs. These mosquito-like insects are attracted to yellow, so they will easily get caught in yellow sticky traps. You can also hang the traps near plants in nurseries or indoors to catch new adult gnats flying in.