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How To Control Fungus Gnats

Do Fungus Gnats Carry Diseases

How to Control Fungus Gnats Indoors – Very Effective Method

Fungus gnats have no known transferable disease to humans.

However, they can carry diseases like pythium which can spread between plants.

This disease can cause damping-off and kill small seedlings. Its spread by touching other plants that have pythium and sticks to their feet. They can also pollinate and transfer mushroom spores.

Preventing Fungus Gnats In Houseplants

Fungus commonly gnats get into a house either because the plants have been outdoors, where adult gnats can lay their eggs into the soil, or the plants came from their source with contaminated soil. The only way to prevent this migration is to avoid bringing the plants inside. Of course, houseplants by definition live indoors, so this is not a permanent solution. The answer is to quarantine new plants or those that have been outdoors for extended periods. Keep the plants in their own room for at least 17 days , and inspect the plant carefully for the presence of adult gnats. Once the plant has the all-clear, you can bring move it in with your other plants.

As an ongoing prevention method, be careful not to overwater your houseplants, since soggy soil and a full runoff saucer are just what the gnats are looking for. Let the soil dry between waterings, but only as much as the plant will tolerate this is no reason to threaten your plant’s vitality.

Always Quarantine New Soil

When you buy new soil from the store, you should quarantine it by placing it in an isolated container.

Check the soil every few days for two weeks. Youre looking for bugs, eggs, and other pests.

Youll have to stir the soil to make sure you dont miss any maggots, worms, or nymphs hiding deep in the soil.

This should be something you do with anything that you plan to add to your yard- just like quarantining plants.

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Water Plants From The Bottom

Fungus gnat larvae live in the top inch of the soil, which tends to stay pretty moist when you water plants from the top.

Bottom watering plants will make it easier to maintain dryer top soil, without risking the overall health of the plant.

To water your plants from the bottom simply pour water into the plants drip tray or cache pot, and allow the plant to soak up the water through the drainage holes.

Never allow your plant to sit in water for too long. Dump out any remaining water after about 30 minutes of soaking.

Eradicating fungus gnats by bottom watering plants

Natural Pest Fungus Gnat Control With Hypoaspis Miles

Fungus Gnats: How to Get Rid of Fungus Gnats in ...

Predatory mites, like hypoaspis miles and hypoaspis mites, feed on small, insects that inhabit moist soil, primarily the fungus gnat larvae. If you are into organic gardening, you can release the hyposaspis miles into the soil of your plants before the fungus gnats become well-established.

The mites, like the nematodes, will feed on the fungus gnat larvae, eliminating the problem before you even see an adult fungus gnat take to the skies.

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Where Do Fungus Gnats Come From

Fungus gnats feed on decaying plant matter and fungi and thrive in moist conditions, such as soil, which is where they lay their eggs, says Derek Gaughan, founder of the DIY pest control website Bug Lord. If you own a lot of houseplants, you are more susceptible to having a problem as this is their ideal habitat.

With so many of us working from home these daysand at risk of overwatering our plantsits no surprise that these critters are out in full force. How many times a day have you walked by your favorite houseplant and decided to water it?

The best thing you can do is avoid overwatering your plants and to let the soil dry out between waterings, says Gaughan.

You might also notice an infestation of fungus gnats shortly after repotting your houseplants or after bringing new plants into your home. This is because bugs sometimes hitch a ride inside bags of potting soil or plants from home improvement stores. They can also make their way indoors if you set your houseplants outside to get some sunlight then bring them back in.

Nematodes For Fungus Gnats

You can top dress your houseplants with Steinernema feltiae, or beneficial nematodes to destroy the fungus gnats during their larvae stage. The microscopic roundworms penetrate the fungus gnat larvae, then release a bacterium that works to consume the insect from the inside out. They are safe to use around plants, pets, and your family.

Before adding the nematodes to the soil, make sure you soak the area because, like the fungus gnat, they prefer dark, moist environments. Once youve added the nematodes to the soil of your houseplants, they will get to work feeding on any gnat larvae that they find.

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Are Fungus Gnats Bad For Plants

Fungus gnats are harmless towards plants as adults.

But the gnat larvae have been known to chew on plant roots under the soil surface and stunt plant growth. The larvae are the destructive part of the fungus gnat life cycle, as with most other larval pests like worms and caterpillars.

You may notice your younger seedlings and leaflets growing slower, wilting, or drooping. This may be the result of the fungus gnats damaging the plants root system.

When there are many larval gnats, they can quickly overtake a young plant and slowly kill the plant over time.

Just a few wont hurt, but when there are many of them eating away at the root system, the plant will have difficulty absorbing nutrients from water and soil. Thus, the plant may be killed when there are many fungus gnats.

How To Stop And Prevent Fungus Gnats In Your Garden

How To Control Fungus Gnats

When it comes to gardening, especially indoors, nothing is more evil and annoying than the old FUNGUS GNAT.

Now, Iâm not here to bore you with information about the biology of the fungus gnat, and what itâs doing in great lengths, but I will explain some methods Iâve used to stop the spread of gnats and prevent them in the first place.

Letâs go!

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Hydrogen Peroxide Controls Larvae

Mix one part 3% hydrogen peroxide with four parts water. Allow the top layer of your soil to dry, and then water your plants with this solution as you normally would. The soil will fizz for a few minutes after application this is normal.

Contact with hydrogen peroxide will kill fungus gnat larvae on contact. After a few minutes the fizzing stops and the peroxide breaks down into harmless oxygen and water molecules. Repeat as needed.

Best Pest Control Companies

Homeowners who wish to save time and hassle can work with a professional pest control provider to treat their gnat infestation. The This Old House Reviews Team evaluated every major pest control company in the industry and found that Terminix, Orkin, and Aptive provide the best service.

Each of these companies will implement a customized treatment plan for your home and educate you on ways to prevent a future infestation. Use the table below to compare the best pest control companies and get a free quote.

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And That Is How You Prevent And Get Rid Of Fungus Gnats In Houseplants

I hope that these tips will help you and your houseplants happily thrive, pest-free and healthy. If you are having issues with other houseplant pests such as aphids or mealybugs, check out our simple soap spray recipe to battle those buggers! Please feel free to ask questions in the comments below, or share this article with your friends. Thanks for tuning in!

For more information on garden pests, see this series of articles:

Will Repotting Plants Get Rid Of Fungus Gnats

Fungus gnats

Not really.

Repotting your plants that already have fungus gnats wont do much and can actually help the pests infest new plants. If the gnats are clinging to the repotted plant, you may inadvertently transport them from one planting site to another.

Unless you soak the plant in a solution that kills all fungus gnats, there will likely be some clinging onto the leaves, roots, or stem that you miss.

Repotting only works if you can 100% make sure that there are NO nymphs on the plant before you replant.

Otherwise, you need to treat the plant in the same soil. You can always try replacing the soil with new soil if this is the case.

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How To Identify A Fungus Gnat

  • Size: Adult fungus gnats are tiny. Their size ranges from about 1/16 to 1/8 of an inch in length , which is about the same size as a fruit fly. Fungus gnat larvae may be up to 1/8 of an inch in length.

  • Appearance: Adult fungus gnats are a grayish-black color and have gray or see-through wings. Their long legs and long antennae give them a mosquito-like appearance, though they are much, much smaller in size. Compared to a fruit fly, fungus gnats have a thinner body with longer legs and antennae.Larvae have a small, black head and a thin, white or see-through body.

  • Activity: Fungus gnats tend to spend most of their time on the soil surface of potted plants, but they may be seen flying around the outer edge of the pot or near drainage holes as well. They are not strong fliers, so they have a tendency to walk along the soil and fly only in short bursts. Their flight is erratic and they are much slower than fruit flies, acting more like mosquitoes while flying.Annoyingly, fungus gnats have a tendency to fly into peoples faces and drinks, though they are completely harmless and a few well-placed swats will show them whats what.

Eliminate Fungus Gnats With Diatomaceous Earth

An effective pest control solution for dealing with fungus gnats is food grade diatomaceous earth . DE is made from the fossilized skeletons of diatoms.

When the fungus gnat larvae come into contact with the razor-sharp powder, it removes the waxes from the insects body and absorbs the oils located on their outer cuticle. This causes them to become dehydrated and die. To use DE for your fungus gnat problem, sprinkle some of the powder on the soil around your potted plants.

This will help keep the topsoil dry and kill any larvae that are already in the ground. It is essential to continue to add diatomaceous earth after watering the plants to keep the gnats away.

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Habitat Diet And Life Cycle


Widely distributed, fungus gnats thrive particularly well in forested areas around the world. Given their poor flying abilities, they nest close to their breeding spots. Potential sites of infestation include the wet humus-rich soils or potting mix of potted plants indoors and outdoors, swamps, decaying vegetation, greenhouses, compost piles, and other sources of decaying organic matter.


Adult fungus gnats have a liquid diet and primarily consume water and flower nectar. During the larval stages, they feed on decaying organic matter and fungi.

Life Cycle

Although adult fungus gnats only live an average of 10 days, females lay approximately 150 eggs in their lifetime. They deposit the eggs directly onto food sources like damp plant soil. Hatching within a week, fungus gnat larvae feed for up to two weeks before pupating and adults emerge approximately a week later. Fungus gnats produce several generations each year and are most active during warmer weather. Depending on the temperature, they complete their life cycle in 21 to 40 days.

What To Know About Fungus Gnats

How To Control Fungus Gnats The Fun Way – This Plant Eats Fungus Gnats

Fungus gnats are small, dark-bodied flying insects about 1/8 inch in length. Their life cycle includes four developmental stages egg, larva, pupa, and adult. Adult females lay their eggs into moist soil and the larvae emerge four to six days later. The larvae have translucent bodies and dark heads. They live in the soil for approximately 2 weeks, feeding on fungi, decaying plant matter, and plant roots. Then the larvae pupate and emerge three to six days later as flying adults. Adult fungus gnats live for one week, and during this time the females can lay up to 200 eggs. Since the entire life cycle is completed in 3-4 weeks, overlapping generations eventually magnify the problem.

A small population of fungus gnats rarely does significant damage, but in large numbers they can be a serious problem. Potted plants that are suffering from a severe fungus gnat infestation can show signs of wilting, loss of vigor, poor growth, and yellowing.

Fungus gnat larvae.

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What Temperature Kills Gnats

Gnats are difficult to kill by temperature alone.

They can withstand both freezing and extreme heat. Some people will attempt to freeze their potting soil to get rid of the gnats. This works, but it requires very low temperatures for a sustained

period of time.

You can try freezing small amounts of soil by placing it into a zipper bag and freezing it for 3 days. This may take multiple attempts before you kill all the gnats.

On the other hand, you can also use heat to kill gnats.

Pour the soil into a container and seal it with plastic food wrap. Place the container outdoors on a hot day in direct sunlight and the container will heat up. Let it sit out for the entire day.

Wait until the next day during sunrise to unseal the container and check for gnats. Be careful as it may be hot. The point of leaving the container out overnight is to suffocate the gnats using the trapped heat.

Both of these measures dont work as well as others, so using temperature for gnat control is a poor methodology. Dont rely on it to do anything unless you have extreme lows or highs.

Gnats live comfortably between 75-80 degrees. Youll want to use temperatures below 20F or above 100F to kill them.

Note that they can stand freezing temperatures because they have proteins that prevent this. Thus, they can both overwinter and tolerate extremely cold temperatures.

Getting Rid Of Fungus Gnats

The bane of my existence is the fungus gnat . This insidious little creatures larva love to inhabit overly wet soils. Their larval feeding habits can damage plant roots, even stunting or killing seedlings or less established plants. Adults leave the soil and fly, often to flutter straight into your mouth or nose. Here are 8 ways to get rid of fungus gnats in your houseplants. For best success I like to combine a few methods.

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Will Fungus Gnats Go Away On Their Own

If they consume their entire food source the colony can die of starvation. Otherwise, like outdoors, they can thrive for long periods of time before naturally migrating to other locations.

Direct action is encouraged to get rid of fungus gnats, as opposed to hoping they leave on their own, due to their rapid replication.

How To Treat Fungus Gnats

Fungus Gnat Identification, Habitat &  Dangers

Adult Fungus Gnats stuck to a yellow fly trap. They are often mistaken for fruit flies. Photo by Lauren Sottile.

Fungus gnats are one of the most common houseplant pests we get questions about, and for many people can be one of the more annoying issues in dealing with houseplant care. These gnats families Mycetophilidae and Sciaridae) feed on small bits of fungi and decaying matter in the soil, which is present in any healthy soil medium. Populations of fungus gnats can quickly grow out of control, as their breeding cycle is very short, and although minor infestations are generally not harmful they can interrupt the serenity of keeping an indoor garden. Adult fungus gnats dont damage plants or bite people but larvae can damage roots and stunt plant growth if the infestation is allowed to continue unabated. Thankfully, there are multiple methods that are effective at dealing with fungus gnats, and with a little care and attention they can be dealt with rather quickly.


Fungus gnats can also be problematic in the warmer months as they can easily slip in through a window . Anyone who has kept plants for an extended period is most likely to have dealt with them at some point, but because they can only thrive under certain conditions they can be easy to treat, so long as the population is not allowed to grow out of control.


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How To Stop Fungus Gnats Spreading To Other House Plants

Fungus gnats like to spread from plant to plant. This means that if you have one infested house plant, you run the risk of infecting all the other house plants in your home too.

The best way to protect your house plants from the spread of fungus gnats is to separate the healthy plants from the infested plants. Quarantining the fungus gnat infested house plants is a good first step.

Start treating your infested plants immediately and consider carrying out the same treatments on your other plants. This can serve as a preventative step, just in case larvae or eggs have found their way into their containers.

Cultural And Physical Control

If youre looking for an easy and effective way to deal with these little flies, every reputable source you check will agree on one foolproof method:

Alter the environmental conditions.

Fungus gnats are often associated with overwatered houseplants. Sure, not overwatering your plants is often easier said than done, but saturated potting medium is very attractive to laying females, not to mention the perfect environment for the wiggly baby fungus gnats to develop in.

As an alternative, you can bottom water your plants so the soil surface, where the eggs are laid and larvae prefer to hang out, never stays soggy.

Speaking of healthier plants, make sure they receive adequate light and ideal temperatures for whatever variety you are growing.

Also avoid fertilizing with lots of manure, blood meal, or other products that are high in organic matter, since these flies love these carbon-rich materials when they begin to deteriorate.

Repot your plants regularly, especially when you notice signs of potting medium degradation. These signs include the medium not drying out as fast as it used to, compaction, and a lack of varying particle sizes.

Test how the medium is doing by getting dirty: feel it with your fingers, dig around a little, and crumble a small handful back into the pot. If the medium is hard , fine, and uniform , you may need to repot.

Remove any decaying leaves or other plant bits whenever you see them.

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