How to Get Rid of Fungus Gnats (and what NOT to do)

Question: What is more annoying than little black bugs flying around your face and falling into your tea while you are reading your favorite book?

Answer: NOTHING!

Fungus gnats are the uninvited guests that hitch a ride along with your houseplants. Without proper management, you could potentially end up with a constant cycle of never – ending black insects.

The good news – they are only ‘guests‘ and can be eradicated.

how to get rid of fungus gnats

The key is interrupting the growth cycle and coming at them from several directions.

However, before you get your flaming torches and pitchforks out, we need to get up and close and personal with Mr Fungus Gnat.

The Fungus Gnat Lifecycle.

know your enemy quote

As the wise Denzel Washington once remarked, we need to get to know our enemy.

In this war, that means to truly get rid of fungus gnats for good, we need to understand each stage of their lifecycle.

Don’t worry, we’re not going to go into the family tree and learn about Great Uncle Fungus and Great Grandmother Gnatty.

We are going to be learning and understand how fungus gnats reproduce. This way, we will be able to hit them on multiple fronts, with the goal of successfully interrupting their breeding cycle.

There are three main stages of a fungus gnats life. Let’s begin with the one that you can see, adult fungus gnats.

Adult Fungus Gnats

Adult Fungus Gnat

The typical length of an average fungus gnat adults’ life is around 7 days. They sure are overly annoying for that one week!

Adult fungus gnats are the ones that you see flying around your house and indoor plants. Throughout their short life, an adult can lay up to 300 eggs. Are you beginning to see why you have a plague proportion problem on your hands?

They love to seek out moist, nutrient rich soils to lay their eggs – which is where your indoor plants come into the equation.

Fungus Gnat Eggs

Fungus Gnat Eggs
credit: epicgardening

Fungus gnat eggs are not easily seen, and you would have to be really looking for them to notice them in your soil.

If you do decide to go poking around, you would only have to look at the soil surface of your houseplants, because female gnats only lay them on the surface of moist soil.

Larvae Fungus Gnats

Fungus Gnat Larvae

After about 4 – 6 days, fungus gnat larvae emerge from the eggs. They have a translucent appearance with a black, shiny head. They are generally very small, but mature larvae can measure up to 7 millimeters in length.

If you have a large scale fungus gnat issue, chances are you will be able to see them wriggling about when you move the topsoil around with a finger. During the larval stage, the larvae feed on the plants’ rotting roots while they mature for 10-14 days.

Once the larvae have fed enough, they will form a pupa that lasts a further 3-4 days. During this period, they will transform into young adult Fungus Gnats which are able to fly.

And there you have it, a complete fungus gnat’s lifecycle.

How to Get Rid of Fungus Gnats – Permanently!

Okay, so we now know the enemy.

We understand how and where they are at different stages of their lifecycle.

Now, we need to form a strategy to tackle the problem at each level of the reproductive cycle.

Below, we will set out strategies that must be implemented all together. It will be a cohesive three-pronged strategy that will hit the fungus gnats at each stage of the reproductive cycle.

Eliminating fungus gnats involves a three-pronged strategy that must be implemented simultaneously.

The easiest way to explain the strategies is to break them down into the stages of the fungus gnat’s life cycle. So let’s get into it.

Getting Rid of Adult Fungus Gnats

getting rid of adult fungus gnats

The first prong in our strategy is to target the adult fungus gnats.

Our goal here is to catch these insects, and keep them away from any moist soil, so they cannot lay any eggs and prevent future infestation.

Preventing more eggs from being laid in your indoor plants’ soil is key to breaking the life cycle of the fungus gnats.

There are several methods for achieving this goal:

  1. Yellow sticky traps are great for catching a great number of fungus gnats. There is no denying it, the proof is stuck onto each strip of sticky tape.

    Place your sticky traps around the areas of your plants that have the highest concentration of adult gnats. We do also recommend monitoring your traps, and replacing strips that become crowded and full of dead gnats.

  2. Covering your soil with a growing medium that the adult fungus gnats cannot penetrate is another strategy we highly recommend. By creating a barrier between the fungus gnats and the soil, you are preventing them from getting the necessary organic matter they need to lay eggs and reproduce.

    You could try using plastic sheeting to cover your soil. It is extremely effective, but we found this to be quite fiddly trying to cut out the right shapes and leave holes for the stems of the plants.

    Another solution is to use a layer of potting sand around a 5-7 millimeters thick. You need the sand to be thick enough to prevent the adult gnats from digging down.

Recommended Reading:

If you are into a bit of DIY and using natural products, like vinegar and dawn dish soap, be sure to check out our list of DIY gnat traps using household items. They are effective a budget-friendly ways to catching the adult fungus gnats.

Getting Rid of Fungus Gnat Eggs

The next prong in our strategy is to target the eggs that have already been laid in the soil.

  1. Reducing your watering frequency can help to eliminate the breeding ground that fungus gnats seek to lay their eggs. This means you need to make sure ALL your indoor plants’ soil is dry for a period of time.

    Fungus gnats need moist soil to reproduce, and they will seek it out wherever they can get it. This means they will go from pot to pot until they find what they need. If you have plants that are not tolerant of short periods of dryness, we would suggest moving them to a separate part of the house OR moving the infected plants outside undercover (where rain cannot reach them).

    When you are drying out your soil, use the soil moisture finger test to make sure the soil is dry to a depth of at least 1-2 inches. Only then should you consider topping up your plant with water.

Getting Rid of Fungus Gnat Larvae

Our final prong in the strategy is to focus on the fungus gnat larvae. In fact, many of the strategies we have employed in the other two prongs will help to naturally reduce the larvae numbers.

  1. Covering your soil with a layer of sand, not only helps to prevent the adult fungus gnats from laying their eggs. It also helps to stop the current fungus gnat larvae already in the soil from surfacing.
  2. Drying out the soil when you reduce your watering will help to kill off some immature larvae. This is because the fungus gnat larvae require a moist environment in order to survive. For those of you with a keen eye, you will have noticed we only said it will kill ‘some‘ of the larvae. This is because strong larvae can go into hibernation and resume their way when the soil becomes moist again. For those, we recommend using the next strategy.
  3. Nematode soaks are a great way of rounding out the final prong of our comprehensive strategy for getting rid of fungus gnats.

    What are nematode soaks?‘ we hear you asking. Yes – admittedly, it sounds like something out of a science fiction movie. But beneficial nematodes are actually microscopic roundworms that live in the soil. They naturally feed on the fungus gnat and are an extremely efficient way of eliminating the larvae.

    Did you say roundworms?!‘, we understand some people may be grossed out by the thought of roundworms wriggling about in their pot plants. However, the good news is that you cannot see the nematodes, and they are harmless to people and pets.

    You can find beneficial nematode products online (like Amazon) or at your local nursery. Each has its own instructions for applying to your indoor plants, and we recommend following their guidelines.

Check out how to apply nematodes with this short video by Betsy Begonia on Youtube.

So there you have it. The tried and tested Garden Bench Top 3 pronged attack for completely eliminating fungus gnats.

How NOT to get rid of Fungus Gnats!

We have read many people suggesting remedies and solutions to fungus gnats in online forums. We’ve even heard advice handed out at our local nursery. But many solutions fall short for one primary reason.

They only addresses part of the fungus gnat infestation – leaving you frustrated and pulling your hair out.

For instance, people swear by sticky traps. And we admit, they work. But if you only use sticky traps, you may think you are getting results because you can see the countless bodies of fungus gnats sticking to the brightly lit traps. You may even be able to see a noticeable decrease in the amount of gnats flying around the house.

However, your problem will be back again within a fortnight when the larvae have matured into adult fungus gnats again.

So, reading between the lines, don’t be fooled into thinking one strategy will be the solution. We recommend taking a holistic approach to your problem, and implementing the strategies laid out in our 3 pronged method above for complete elimination of your gnat problem.

Do you have Fungus Gnats?

What if you tried all the strategies above, but you still have annoying black insects flying around your house?

The next step would be to consider, maybe we have an identification issue?

How to Identify Fungus Gnats

If we were to describe fungus gnats in two words it would be ‘miniature mosquitoes’.

Your best bet in seeing one up close is to use the sticky traps to catch one and put it under a microscope.

These annoying little creatures look awfully similar to those blood sucking creatures who seem to get a lot of enjoyment doing laps around your head at night.

They have black bodies, with long antennae, long legs and opaque wings (very much like a mosquito, only miniature).

Fungus Gnat vs Fruit Fly

Many people often mistake them for fruit flies. However, if you held them side by side, you would easily see the body shape and color is very different. Fruit flies have thicker, rounded bodies that are orange in color.

One final way of telling the difference between fruit flies and fungus gnats, is if you don’t have any indoor plants then it is more likely to be fruit flies. As we have explained above, fungus gnats require damp soil to survive and thrive. Without the presence of wet soil, their reproduction cycle cannot continue.

Fungus Gnats: Frequently Asked Questions

In this section we attempt to answer all your ‘other’ questions that may not be addressed in our guide.

If you don’t find an answer to your question, please send us a message via our CONTACT page. We will endeavor to respond with a timely answer, and include it in our growing FAQ section below.

Do Fungus Gnats Die in Winter?

If your house temperature drops below 60° Fahrenheit (15° Celcius), you will notice fewer fungus gnats buzzing around your plants. This is because they prefer warmer temperatures and many won’t survive the cooler conditions.

Unfortunately, cooler temperatures won’t stop the lifecycle of fungus gnats. The eggs and larvae will simply remain dormant until the weather improves and gets warmer.

Do Fungus Gnats Bite Humans?

Fortunately for those with fungus gnat plagues in their house, the good news is they do not bite. Actually, besides being annoying and occasionally ruining a cup of tea, they are relatively harmless. Fungus gnats do not bite, sting or cause any diseases in humans or pets.

They can affect the health of your indoor plants. As pointed out above, the fungus gnat larvae feed on rotting plant roots, weakening them and potentially leaving them exposed to other diseases.

What is the Fastest Way to Get Rid of Fungus Gnats in Your House?

The fastest way to get rid of fungus gnats in your house is to get rid of all your potted houseplants. Fungus gnats need moist soil to continue their reproductive cycle.

If this seems like an extreme move for you, then we would advise you to follow our three-pronged strategy detailed above, combined with a bit of patience.

How Long do Fungus Gnats Live?

If you are wondering how long the annoying black insects buzzing around your house live for, these are adult fungus gnats, and they live for around seven days.

On the other hand, if you are wondering what the typical lifecycle of a fungus gnat is, from egg to maturity, then you will be looking at a period of around 3 – 4 weeks depending on the temperature and conditions of the soil they live in.

Does Dish Soap Kill Fungus Gnats?

Yes and No. Dish soap alone probably won’t be sufficient to kill fungus gnats. You should probably combine the solution with some vinegar and/or sugar. Both substances will attract the fungus gnats towards the dish soap. Once the gnats come into contact with the soap, they will get stuck and likely drown or starve.

Will fungus gnats go away on their own?

Unfortunately, the answer to this one is a resounding NO. Without being proactive and a properly managed strategy to attack each stage of the fungus gnat lifecycle, your infestation problem will remain. We recommend re-reading this article and familiarizing yourself with our three-pronged strategy for complete elimination of fungus gnats.