Gardening Guides
How to Get Rid of Gnats Around the House
See swarming bugs in your plants or garden? Focus on the health of the soil and be naturally pest-free
If you want to know how to get rid of gnats, the first thing you need to do is understand what kind of bug you’re dealing with. The word gnat is a sort of catch-all term for any swarming fly, and people use the term colloquially to identify a range of bugs inside and outside the house. Generally, if you see small insects flying around food or fruit in, say, your kitchen, those are fruit flies. (They love bananas, by the way.)
If you’re seeing small swarming insects outside your house in your potted plants or near soil, those are most likely fungus gnats. As for how to get rid of gnats outside, it’s pretty straightforward, and involves paying more attention to plants and soil rather than the bugs themselves.
If you’re seeing small swarming insects outside your house in your potted plants or near soil, those are most likely fungus gnats. As for how to get rid of gnats outside, it’s pretty straightforward, and involves paying more attention to plants and soil rather than the bugs themselves.
If you do suspect gnats in your soil, don’t move your plants around, especially from outside to inside your home. This will prevent the gnats from spreading to other areas.
Can You Use White Vinegar to Get Rid of Gnats?
If you see gnats in your plants, don’t reach for the vinegar, as some articles and blogs suggest. In fact, Tweit and Cloonan both advise against putting any sort of home-remedy solutions on your plants and soil. That includes vinegar, soap solutions, cinnamon, vanilla and so forth.
“Those can do more harm than good if your goal is to improve plant health,” Cloonan says.
Tweit says white vinegar can turn the soil acidic. “That can burn roots to death,” she says. “You want to be cautious about what you add to the soil ecosystem.”
Can You Use White Vinegar to Get Rid of Gnats?
If you see gnats in your plants, don’t reach for the vinegar, as some articles and blogs suggest. In fact, Tweit and Cloonan both advise against putting any sort of home-remedy solutions on your plants and soil. That includes vinegar, soap solutions, cinnamon, vanilla and so forth.
“Those can do more harm than good if your goal is to improve plant health,” Cloonan says.
Tweit says white vinegar can turn the soil acidic. “That can burn roots to death,” she says. “You want to be cautious about what you add to the soil ecosystem.”
Other Preventative Measures
Quality soil. Tweit says it’s a good idea to buy quality soil to begin with, but not because it will keep away gnat larvae. Those will show up if you overwater any kind of soil. But higher-quality soil means more nutrients, resulting in healthier plants and roots. That can mean if you do have a fungus gnat problem, your plant and its roots will be better able to fight off attacks on its systems until you can step in and cut back the water.
Remember, you want to clean out planter trays and drains as well.
Read more on getting the right soil
Quality soil. Tweit says it’s a good idea to buy quality soil to begin with, but not because it will keep away gnat larvae. Those will show up if you overwater any kind of soil. But higher-quality soil means more nutrients, resulting in healthier plants and roots. That can mean if you do have a fungus gnat problem, your plant and its roots will be better able to fight off attacks on its systems until you can step in and cut back the water.
Remember, you want to clean out planter trays and drains as well.
Read more on getting the right soil
Why Do Gnats Swarm?
Some people think gnats swarm because they’re attracted to the heat from your body, the carbon dioxide emitting from your mouth, the moisture in your eyes or the soap or perfume products on your skin. None of that has been proven, according to Cloonan and Tweit.
Evidence has shown that when gnats are swarming, they are doing so because a female is within that swarm producing a compound sex pheromone, which excites the surrounding males who are trying to mate with the female. That’s right: When you’ve encountered a swarm you’re actually interrupting a sex party.
What to Do About Swarming Gnats
Let’s say you’re having a lunch or dinner party in your backyard and before the guests arrive you discover that you have a fungus gnat problem. While this type of gnat isn’t attracted to food, you might want to do something to prevent them from swarming above walkways through your yard or garden, since you can’t really wait the week to let the soil dry out and the larvae and gnats die off.
The quickest fix, Tweit says, is to set up a few citronella candles or torches.
Cloonan suggests searching for yellow sticky tape rolls. Adult gnats are attracted to the yellow color and get stuck to the tape.
Some people think gnats swarm because they’re attracted to the heat from your body, the carbon dioxide emitting from your mouth, the moisture in your eyes or the soap or perfume products on your skin. None of that has been proven, according to Cloonan and Tweit.
Evidence has shown that when gnats are swarming, they are doing so because a female is within that swarm producing a compound sex pheromone, which excites the surrounding males who are trying to mate with the female. That’s right: When you’ve encountered a swarm you’re actually interrupting a sex party.
What to Do About Swarming Gnats
Let’s say you’re having a lunch or dinner party in your backyard and before the guests arrive you discover that you have a fungus gnat problem. While this type of gnat isn’t attracted to food, you might want to do something to prevent them from swarming above walkways through your yard or garden, since you can’t really wait the week to let the soil dry out and the larvae and gnats die off.
The quickest fix, Tweit says, is to set up a few citronella candles or torches.
Cloonan suggests searching for yellow sticky tape rolls. Adult gnats are attracted to the yellow color and get stuck to the tape.
A dark fungus gnat. Photo by Katja Schulz, via Wikimedia
More-Drastic Measures
If cutting back on watering and letting the soil dry out doesn’t fix your fungus gnat problem, you have a couple of options. Cloonan recommends moving on to a biological method of treatment.
The first is something called Bti (Bacillus thuringiensis subsp. israelensis), which is a protein crystal that kills larvae when it’s ingested. It’s mostly nontoxic to humans and other mammals. A house cat, for example, would have to eat a whole lot of it for it to be harmful, Cloonan says. The most common brand name is Gnatrol, though it typically comes in very large quantities for big-scale production issues. If you search for Bti you can find cheaper, small-scale products. Cloonan recommends this one.
The other biological method to try is beneficial nematodes. These are live microscopic organisms (worms, really) that feed on larvae and pupae in soil. Arbico Organics is a good place to do more research and find products.
The University of California Agriculture and Natural Resources offers a helpful integrated pest-management program for dealing with fungus gnats. The Missouri Botanical Garden website is another good resource.
More
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More-Drastic Measures
If cutting back on watering and letting the soil dry out doesn’t fix your fungus gnat problem, you have a couple of options. Cloonan recommends moving on to a biological method of treatment.
The first is something called Bti (Bacillus thuringiensis subsp. israelensis), which is a protein crystal that kills larvae when it’s ingested. It’s mostly nontoxic to humans and other mammals. A house cat, for example, would have to eat a whole lot of it for it to be harmful, Cloonan says. The most common brand name is Gnatrol, though it typically comes in very large quantities for big-scale production issues. If you search for Bti you can find cheaper, small-scale products. Cloonan recommends this one.
The other biological method to try is beneficial nematodes. These are live microscopic organisms (worms, really) that feed on larvae and pupae in soil. Arbico Organics is a good place to do more research and find products.
The University of California Agriculture and Natural Resources offers a helpful integrated pest-management program for dealing with fungus gnats. The Missouri Botanical Garden website is another good resource.
More
How to Get Rid of Fruit Flies
Organic Matters: Thwart Insect Pests With Trap Crops
More Houzz Gardening Guides
Where Do Gnats Come From?
If you’re dealing with a fungus gnat in your garden, the first thing you should do is stop watering. Gnats hatch from larvae in soil, where they feed on microorganisms and bacteria. If you keep your soil wet for too long, it’s a ripe breeding ground, and eventually gnats will grow and start buzzing around.
How to Keep Gnats Away
- Stop watering for a week or so.
- Clean out planter trays and drains.
- Let the soil dry out.
Putting the brakes on watering will dry the soil out and kill the larvae. After that, your problem should be solved, as long as you don’t overwater.This approach is what entomologists like Kevin Cloonan, who’s also a post-doc researcher at Rutgers University, calls integrated pest management. The method addresses insect pests not through chemical insecticides but through figuring out the variables that are creating the insect situation in the first place, then mitigating those. When it comes to controlling fungus gnats in residential backyards and gardens, that means water management and sanitation.
“If you see fungus gnats, cut back the water,” says Susan Tweit, a plant biologist. “Overwatering is not good for soil or root health. It’s a hygiene problem. Just pay attention to what’s going on in the ground and under potting trays.”