How to Get Rid of Gnats for Good

If you have a gnat problem, you may have noticed them swarming around your house plants, hanging out by your fruit bowl, or congregating by your trash can. They're a common problem, so you're definitely not alone. Not only are they unsightly, they can also do damage to your plants if you don't eradicate them quickly.

Fungus gnats are the most common type found around house plants. While fungus gnats do not bite people, fungus gnats and other flying insects can attack your plants and ultimately lead to their demise. Read on to learn how to get rid of gnats, with tips from the experts on how to banish and prevent gnat infestations.

How to Identify Gnats

Flying insects are often lumped into the term "gnats," but in reality, there are different kinds likely bugging your home. Fruit flies like to hang out near old and/or decaying fruit, as their name implies. Drain flies are the ones that you'll occasionally see buzzing around your sink, and they live off of any organic matter buildup in the drain. “There are different types of gnats, but the ones you’re going to be seeing buzzing around your plants are fungus gnats, which feed on decaying plants, like those leaves that are turning yellow or brown or getting crinkly,” says Jennifer Schutter of Plantcarefully.

While adult fungus gnats are more of a nuisance than a danger to plants, their larvae can stunt plant growth and damage plant roots. Larvae, which are early-stage gnats in maggot form, feed on organic matter and chew on plant roots. These larvae often flourish in the soil of potted plants. Large numbers of gnat larvae can significantly damage young plants and seedlings. Though the methods below focus on fungus gnats, or the type that prefer plants, they can generally be used to combat any type of flying insect.

Causes of Gnat Infestations

Gnat infestations occur when several gnats reproduce, which they do quickly.  “Often, the first sign of a gnat infestation is the sight of small, dark flying insects hovering around the soil of your houseplants,” says Tony O’Neill of Simplify Gardening. “They are particularly active when you water the plant.”

Other signs of a gnat infestation are your plants wilting, losing leaves, and turning yellow. Slow plant growth can be another sign of a gnat problem. Gnat infestations can weaken your plants and make them more susceptible to other pests and diseases. Some common things that attract fungus gnats include:

• Moist soil
• Decaying organic matter, such as compost piles and manure
• Overwatered plants
• Dirty dishes in the sink
• Trash cans that are not emptied regularly
• Fruit bowls that are not covered
• Pet waste

“Unfortunately, simply having plants can be enough since they’re tasty snacks for gnats,” Schutter says. “Indoors, they can squeeze through small cracks or holes in your home, around windows, doors, walls, etc. They can also enter through clogged drains and lay eggs in trash cans and soil.”

Wet soil can be particularly alluring for gnats, which breed in wet conditions. “Overwatering is a prime culprit,” O’Neill says. “When the soil remains consistently moist, it creates an ideal breeding ground for fungus gnats. They’re also attracted to decaying plant matter, so overgrown or dead foliage can contribute.”

Natural Remedies to Get Rid of Gnats

You can employ several natural ways to eliminate gnats from your house plants. Since gnats reproduce quickly, you may need to try a few methods to get rid of them all. Natural methods are the best first line of defense, so try these before turning to chemical solutions.

Allow Soil to Dry Out

First, let your soil dry out completely between waterings. This will cut down on the moisture-rich breeding grounds that gnats love. You can invest in a soil moisture monitor to accurately measure the amount of water in your soil, which will help prevent overwatering.

Get Rid of Decaying Matter

Clear your plants and soil of decaying leaves, flowers, or organic matter. Remove dead flowers, leaves, or other plant parts from your plants. You should also check any fruits that are out for overripeness; gnats are attracted to ripe fruits or ones that have begun to ferment. If you usually keep all of your fruit out, consider moving the ones that can be refrigerated into the fridge to prevent attracting gnats.

Spray Soil

To kill gnat larvae, try a mixture of soapy water and spray it on your plants’ soil, O’Neill advises. Use one tablespoon of liquid soap (such as dish soap) with one quart of water and spray onto the soil to remove gnat larvae. 

Make a Gnat Trap

“Gnats spend most of their lives as larvae and pupae in organic matter like soil, so it makes more sense to target them in this stage than try to get rid of adults, which don’t live long anyway,” Schutter says. One way to get rid of gnat larvae is to make your own gnat trap with a mix of vinegar, dish soap, and sugar. Mix a few tablespoons of apple cider vinegar, a few drops of dish soap, and a sprinkle of sugar. Place the traps in small dishes near where gnats congregate. The gnats will be attracted to the sugar and vinegar and will get trapped by the dish soap and drown, Schutter says. 

Try Raw Potato Chunks

“Another little-known gnat hack is putting raw potato chunks into the soil to attract larvae,” Schutter says. “This has the twofold benefit of drawing them away from your plant’s roots and blocking their access simultaneously. It’s worked wonders for me in the past and keeps things super cost-effective.” Keep the potato chunks in the pots for a few days, then toss them and put new ones in until you don’t see any more signs of an infestation, Schutter advises.

Use Yellow Sticky Traps

Sticky traps are a simple and cost-effective way to get rid of adult gnats. Gnats are attracted to the color yellow, and the traps entice them, where they get stuck to the adhesive. Schutter recommends cutting the sticky traps into squares and taping them to sticks (chopsticks, pencils, skewers, etc.). “Pop the sticks into problem pots, and you’ll see adult gnats start to get trapped almost immediately,” she says.

Repot Your Plants

If your plant soil is infested with gnat larvae and you’re having trouble getting rid of them, repot your plants. Use clean containers and fresh potting soil. Repotting plants can also be an effective way to avoid using insecticides. Just remember that if it doesn't work 100 percent, the gnats may come back.

Chemical Treatments to Eliminate Gnats

Experts recommend trying natural remedies first to remove gnats from your house plants. Natural remedies are eco-friendly and pose no health risks to humans or pets. However, it may be time to turn to chemical options if you try a few natural solutions and still have a gnat problem.

Use Hydrogen Peroxide

Hydrogen peroxide is a useful tool to kill gnat larvae and is a common household item. “You can use 20% hydrogen peroxide (preferably 3%) mixed with 80% water to kill gnat larvae immediately,” Schutter says. “Slowly drench the soil until the mixture comes out of the drainage holes.”

Use Bacillus Thuringiensis Israelensis (Bti)

“While I lean towards natural remedies, products containing Bti can be used to target gnat larvae without harming plants,” O’Neill says. Bti is a naturally occurring bacterium found in soils. Bti kills fungus gnat larvae. Follow the instructions on your product, adding Bti to the soil of your plants. This will kill gnat larvae while leaving your plants unharmed. 

Try Aerosol Sprays

Use an insecticide spray that kills gnats. Aerosol sprays with pyrethrins are very effective at killing adult gnats, Schutter says. To effectively use aerosol insecticides, spray them directly on the gnats from about a foot and a half away. Also, treat any areas where you've seen gnats congregating so they won't return. Just be mindful that insecticides can be harmful to people and pets, so make sure not to get too close to food, utensils, or areas your furry friends like to lay in.

Hire a Professional

If you’ve exhausted your options and still have a gnat infestation, it’s time to call in the pros. Hire a professional pest control company for help. Professional pest companies bring expertise that can save you time and money. They can identify where nests are and ensure safe methods to eradicate them. Often, these pest control companies can access chemicals you can't simply buy in the store that are more effective and efficient at eliminating gnats.

Preventative Measures to Keep Gnats Away

You can take some simple steps to prevent gnat infestations from attacking your house plants in the first place. Keeping your home clean and free of excess water and decaying matter will help ward off gnats. Take these precautions to prevent gnats:

• Avoid overwatering your plants.
• Inspect your plants often and prune off or throw out dead leaves and flowers.
• Use a fine layer of sand or diatomaceous earth on top of plant soil to deter gnats from laying eggs. 
• Use well-draining pots and soils. 
• Inspect new plants for gnats before buying them.
• Seal cracks and holes around doorways, windows, and drains to prevent gnats from entering.
• Clean up damp places and allow them to dry. 
• Use tightly sealed garbage and compost bins and take the trash out daily.
• Do not let dishes and water pile up in the sink. 
• Refrigerate fruits and vegetables as much as possible.
• Keep drains clean so there's no organic matter to attract gnats.