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How to get rid of fungus gnats?

To get rid of fungus gnats, you have to know the right methods to apply.

December 29, 2021

22 min read time

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Did you know that one of the most refreshing benefits of houseplants is their natural ability to help purify the air indoors by absorbing toxins and releasing more oxygen?

Houseplants also help boost productivity and creativity while adding a lovely colorful flair to your garden or your surrounding – but when you find annoying tiny bugs buzzing around in your face now and then inside your home, then that becomes an issue that could grow into a major one if Fungus gnat infestation on houseplants is not treated.

If you already have such problems, sit back and relax! This is all the help you need to get rid of fungus gnats.

What are Fungus Gnats?

Fungus gnats, also referred to as soil gnats, include several tiny, dark-winged, short-lived insect pests often confused with fruit flies. Unlike fruit flies, fungus gnats are known to be attracted to the warm, moist potting soil created for your houseplants.

These harmless gnats usually find their way into your home through small crevices, open windows, or by clinging onto new houseplants that you bring into the home from the garden or nursery. Although they are completely harmless to humans and do not spread diseases, these flies pose a serious threat to houseplants as they grow in numbers -which is usually rapid.

Adult Fungus gnats have long legs and an antenna usually segmented and longer than their heads. They can lay up to about 200 eggs at once towards the surface layer of the moist soil of your potting mix.

The eggs hatch into larvae after about 72 hours and burrow deeper into the potting soil, feeding on the organic matter of the soil, fungi, and root hairs of the plant for a period of 2 weeks.

A few days after, adult gnats emerge from the soil and start hanging around the soil surface. You may oftentimes notice them flying around the edges of the pot or crawling around the moist soil parts.

Why do I have fungus gnats in my house?

Everyone loves to boast about how clean and well kept their surroundings are, yet the puzzling thoughts of how these nasty gnats get into homes remain unanswered. It’s like they travel through space like Antman and appear wherever they feel like!

Well, relax, friend, that’s not exactly how they get in. At least one out of the following reasons is why you get fungus gnats in your house.

1.  Overwatered houseplants

Having over-watered houseplants is the most common cause of fungus gnats in an indoor setting. Fungus gnats breed in the moist soil region of your plants right from the egg developmental stage.

These eggs develop faster in the warm, moist soil into larvae that then feed hungrily on the fungi and organic waste on the soil it was laid in, after which they grow into full adult fungus gnats.

Similarly, over-watered lawns and their surroundings can be a reason why you have these gnats infesting your privacy.

Monitor how much water goes into your houseplant potting and your lawn, fix all broken faucets, sinks, pipes, and mend the crevices in your water-damaged walls.

2.  Unkempt garbage cans

This is, of course, another reason why you have fungus gnats in your home. How well you treat your garbage cans matters a lot if your wish to keep these pests away. Of course, it’s just a garbage can, but it may also be a breeding ground for these nasty pests and other fly species.

Be sure to clean your garbage cans regularly and make sure they are not waterlogged. Adults gnats prefer to lay eggs in damp, cozy spots so that as the eggs develop into larvae, they can easily feed on the fungi around.

Also, ensure that the spot where your garbage cans are located is clean and is rid of trash bags with their mouths open.

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Are fungus gnats harmful to humans or plants?

Fungus gnats are not harmful to humans since they don’t bite and, in their small numbers, are unharmful to your indoor plants.

But then, a study from the University of California shows that fungus gnat larvae in large numbers can severely damage the roots of plants and cause such plants to have stunted growth, especially young plants. This is majorly observed in greenhouses and nurseries.

Since indoor plants are mostly moist, tender, and organically-rich, there may be significant damage to such plants as the larvae feed continually on plants’ roots till they get wilted. The larvae emerge as full-blown adult flies. There are records of severe cases that may result in the death of the plants.

Will fungus gnats go away on their own?

Except you get rid of the adult gnats, you may continue to have gnat infestations in your home as these pests would not leave their newfound habitat on their own.

The female adult gnats are responsible for laying eggs in their hundreds, and this they would continue to do, as long as they have the comfort of damp, waterlogged areas or your houseplants.

The populations of these pests may only increase in such a case, and the life cycle of gnats in your home continues.

So, the question of fungus gnats somehow finding their way out of your home is a no-brainer – It just won’t happen until you take steps to get rid of them.

How do you get rid of gnats in potting soil?

While they may seem insignificant at first, these tiny pests have a way of replicating generations of themselves rapidly and causing havoc to the nice colorful flair that your houseplants give. To effectively rid your potting soil of gnats, you’d have to employ cultural control measures and some insecticides that would help kill the gnats.

Of the many control measures to consider, below are some of the most effective techniques. Let’s get right into it!

1. Avoid over-watering potted plants

Since you are now aware that fungus gnat larvae breed in the moist layers of your potting mix, it’ll be a smart decision to minimize and monitor how you water your houseplants. This may help the soil dry out a bit and drastically reduce the breeding grounds for the gnat’s life cycle.

To hasten this dry-out process, it is advised to gently turn up the sand and mix about 2 inches of soil from the surface with a sterile hand trowel daily.

This process hastens the circulation of air on the moist soil, but it may also help expose hidden fungus gnat larvae within the soil to the air and kill them instantly since they only breed in warm, moist soil.

2. Regular tidying of plant pots

Ensure that your plant pots have good drainage to get rid of excess water as you regularly tidy up the plant. This must entail removing organic debris such as detached or fallen leaves, broken stems,; from the edges and surface of the soil.

With these, you can easily prevent fungus gnats from breeding and feeding on your plants and plant roots.

3. Set traps

Fungus gnat adults are attracted to lights – a cogent explanation for why they mostly hang around windows indoors. Setting yellow sticky traps beside the edges of the plant pots has proved to be an effective means of getting rid of fungus gnats in the home. The gnats would be drawn to the sticky traps’ yellow color, get stuck in them, and die.

When effectively carried out, setting sticky traps and reducing over-watered plants would drastically end the fungus gnats’ life cycle.

4. Apply a pesticide

Suppose you observe that your fungus gnats infestation is still severe after the above control measures, using pesticides to kill these pests, such as hydrogen peroxide, acetamiprid, It cannot be overemphasized. Be sure to apply the hydrogen peroxide or whatever product you may use on the soil surface, strictly based on the manufacturers’ guidelines.

Although Pesticides like hydrogen peroxide are very effective, they would not be strong enough to kill gnat eggs, so the process of spraying the hydrogen peroxide on plants and the surrounding soil must be repeated weekly to kill all the gnats.

It is also advised to dig planting holes and ensure that the diluted hydrogen peroxide coats the inner parts of the holes. This will rid that area of the soil of every microbial activity before planting and also disallow the adult gnats to lay their eggs in such depth of the sand.

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What is the fastest way to get rid of gnats?

Have you been severely troubled by fungus gnats, therefore, seeking the quickest means on how to get rid of fungus gnats? If you’ve had enough of fungus gnats and are tired of seeing your plants wilt away, this is the right spot for you!

Here are some of the fastest, natural methods that would get rid of fungus:

1. Vacuum them up

This is perhaps the fastest way ever to get rid of fungus gnats – it’s fun too!

Wherever you see a swarm of fungus gnats around your indoor plant or in your kitchen, a quick way to kill them and get rid of them from that space is to use a good vacuum cleaner. Turn on the vacuum cleaner, preferably a handheld vacuum cleaner, aim it at the area where you noticed them swarmed up, and slowly revolve the suction point or filter around for about 20 seconds.

Yeah, you can thank me later by coming back for more content! You’re welcome.

2. The Bacillus Thuringiensis method

Bacillus Thuringiensis is a microbial insecticide that lives in the soil. It kills fungus gnats by producing a toxic protein to gnats when ingested, which would conclusively lead to starvation for the gnats.

Bacillus Thuringiensis (BT) is harmless to humans, plants, and pets. It can be applied to the plants from a spray bottle once a week. Its effect becomes obvious after a couple of days.

3. Beneficial Nematodes

Beneficial Nematodes, similar to the insecticide above, are microscopic roundworms that can be naturally found in the soil. These worms gain entrance into the larvae’s body either through their anus, respiratory organs or seep through the body of the fungus gnat larvae.

On gaining entrance, the beneficial nematodes release bacteria that replicate themselves into the fungus gnat larvae’s bloodstream and cause its blood to be poisoned. This single act kills the larvae, after which the nematodes feed on the tissues of the larvae while multiplying themselves.

When the larvae are out of nutrition for the nematodes, they exit the body and begin searching for a new host.

Many products containing nematodes can be used to kill and cleanse soils infested with bugs. With the use of a spray bottle, you can effectively apply nematodes to the affected soil. You only have to ensure that this is done at dusk or dawn or on cloudy days because nematodes seem to be affected by UV light.

Also, because Beneficial nematodes need water to thrive, ensure you wet the soil before and after applying it on the soil. This should effectively kill the fungus gnat larvae.

4. Neem Oil

Neem oil is naturally derived from the neem tree and is a powerful biodegradable, organic solution that has various means of helping to kill fungus in your home. Of the many purposes of this powerful solution, Neem oil can also effectively get rid of fungus gnats as it works both as a pesticide and a fungicide.

It drastically reduces fungus gnats, acts as a good fertilizer, controls nematodes and hundreds of other pest infestations.

5. Apple cider traps

This homemade trap system is one that would surprisingly generate a quick means to kill fungus gnats as you treat the plant and soil. It is almost similar to the sticky traps discussed above, except, in this case, you won’t be needing any sticky surfaces.

I highlighted some points for you below to clearly explain this trapping method. Items needed for this operation are

  • A disposable cup
  • Toothpick
  • Plastic wrap or cellophane
  • Rubber band
  • Apple cider

Step 1:

Pour 2 inches of apple cider into the disposable cup and wrap it tightly with the cellophane material. Use the rubber bands to hold it at the sides of the cup to keep it tight.

Step 2

Poke holes carefully into the cellophane over the cup. The holes must be big enough for gnats to crawl in but small enough to fly out.

Step 3

Leave the trap overnight close to your plant or places where you’ve noticed the gnats. Adult gnats crawling around the top of the soil or around would surely fall into this trap

Step 4

Repeat this step every night.

6. Mechanical Approach

Another approach to ending fungus gnats infestation is to remove about 2 inches from the surface of the soil and discard it in a plastic bag. The chances are that the discarded soil would be rich in fungus larvae.

Next, cover up the removed soil part with sand. The adult female fungus would find it hard to lay their eggs because the organic waste in that spot has been reduced. Allow the soil to dry out properly before watering.


To get rid of fungus gnats, you have to know the right methods to apply. These tiny pests aren’t as dangerous as such, but their large numbers can be a threat to your plant. Regular care for your plant and soil will effectively rid your home of the pests’ presence.

This article would help you live a gnat-free life. You’re welcome!

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