Fungus Gnats - Kamikazes of the Mouth!

Adult Fungus Gnat under magnification

I’ve been asked a LOT lately about how to get rid of fungus gnats. A LOT. So I figured it would be a good idea to share some info about these pesky little jerks, and hopefully enlighten some people that might be struggling with this issue.

One thing we all know for sure, is that we don’t generally want bugs flying around in our homes. The occasional housefly may get in, but that’s the limit for most people! Well, if you have houseplants, you’ve probably encountered a fungus gnat at some point.

They appear to be little bugs, that resemble a fruit fly, or a tiny mosquito. In some cases, you may have seen them congregating around a particular plant in your home, and there’s a very good reason for it- that’s where they live. If you see them all over the soil, crawling around the leaves and stems of a certain plant or 2, its a safe bet that this is where they are breeding, and knowing this will help you combat them.

What is a Fungus Gnat? Well, it’s basically just a flying insect that invades your home, and flies around when you’re sitting at the computer, or reading a book, maybe even eating dinner. They often target your face, sometimes flying into a nostril or being sucked into your mouth while yawning. ANNOYING as HELL!

One thing we can all agree on- FUNGUS GNATS SUCK!

But, how do they come to be in our homes?

And more important- HOW DO WE ELIMINATE THEM???

Well, if you continue to read this blog post, you'll learn the answers to both of the questions, as well as some other important facts about these pesky plant pests.

Fungus gnats are small bugs- often as tiny as only 1.5 millimeters in length- so it's shouldn't come as a surprise to learn that they can get into our homes without being noticed, and fairly easily! Maybe one flew in through the front door with you when you came in from outside. Maybe the larvae were already in a plant you recently purchased from a (big box) store. We've even heard many reports from plant hobbyists after purchasing a widely known, and popular brand of potting soil, only to open it and be confronted with a swarm of fungus gnats. From a brand new, unopened bag of potting soil! So clearly, these bugs can easily move around!

These flying bugs are commonly associated with house plants because their larvae feed almost exclusively on fungi that grows in soil. But these fungi don't grow in just ANY soil. They thrive in over-watered, saturated, or soaking-wet potting soil. These are not uncommon types of soil to have in many house plant enthusiast's homes. With over-watering being such a common thing among plant people, the fungus gnat problem is also quite common!

This existence of fungus gnats in your home does not make you a bad housekeeper, a bad plant parent, or a dirty person. What it may indicate, however, is that you could potentially be over-watering your plants. Even a little bit too much water, or soil that stays wet too long, is enough to start an infestation of gnats!

Are these plant pests hurting your plants? Or are they just hurting your pride? Anyone that's experienced a gnat issue, is probably familiar with the frustration that they bring inside our homes. They aren't the best at flight, but they sure take good practice flights toward our faces, specifically at our noses and mouths! We will talk about why that is a bit later. But first, lets talk about the damage they are doing to your plants.

Honestly, most of the time, a fungus gnat infestation causes minimal damage to your plants. However, their existence is an indicator that damage may already be occurring; due to over-watering. The soil is too soggy for the roots to survive, so they are typically much more prone to rotting away, which ultimately can lead to the death of the plant. Yes, it's true that sometimes the larvae of fungus gnats feed on a the new growth roots of your plants, but the damage is usually not significant enough to be a main contender in the big picture of the plant's health. It's nearly always going to be the fact that the soil is too wet, and the roots are rotting.


person exhales a good amount of Carbon Dioxide from mouth and nose



It's simple really. They are attracted to warm, moist places, which are likely to be suitable places to lay their eggs. They are also drawn to Carbon Dioxide, which is a good portion of what we exhale out of our mouth and nose! It's like Disneyland for them.

Well, what if we just let the soil dry out moving forward? Will this eliminate the gnat problem? Unfortunately, No. The eggs are going to still be in the soil, even the larvae are often dormant, laying in wait for the next time the plant is watered. Then they wake up, and start flying around, reproducing, laying eggs, etc. So this is not a good solution to eliminate the fungus gnat infestation. YES, it is the right cultural change to make- letting your plants dry out more between waterings is a behavior that will help prevent future issues, especially once this one is resolved.

What if we pour hydrogen peroxide in the soil? Won't this kill them?

STOP!! We DO NOT recommend this as a treatment for any plant pests. While it can kill them, and act as a temporary fix, this is not a good solution for the long term. Hydrogen peroxide will kill them in the right strength; in fact, it will kill every organism living in the soil, (and possibly even the plant, if you're not careful!) good or bad. It's not picky. Yes, I mentioned "good organisms" that live in the soil of our plants. There are scores of organisms living in soil- bacteria, nematodes, protozoa, springtails, insects and other bugs- and many of them are what we consider 'Beneficial Organisms'. Even some of the fungi are beneficial for our plants! By pouring a hydrogen peroxide solution into the soil, you are effectively sterilizing it, killing off everything. This is not a good idea. It can stunt the plant's growth, create weakness, and much more. 

Moving on... What CAN I do to successfully get rid of my Fungus Gnats?

Read very carefully:

1. Let your plants dry out between waterings.

2. Remove the top 2 inches of the soil from all your pots, and replace it with fresh potting soil. 

3. Pour a top-dressing layer of fine sand, or small pebbles over the entire surface of the soil.

4. Use a biological treatment.

5. Use Yellow sticky traps to monitor the adults' population.

Fungus gnats have a life cycle of around 24 days. 17 days from hatching until they are a flying adult, at which point they breed non-stop for about 1 week, and then die. After laying a couple hundred eggs on the soil's surface, the adults are dead and gone. 3 days later, the next generation has hatched. One becomes 200. 200 quickly becomes 40,000. This can escalate exponentially, which is why it's important to eliminate them as soon as you can. This can be done by consistently and diligently following the steps mentioned above, which we will go into a bit more detail about next.

Obviously, if they are there because of soggy soil, it makes sense to let the soil dry. Every time. Forever. 

The gnats lay their eggs on and near the surface of the soil, and once they hatch, the wriggling larvae squirm around in the soil, but they can't get much deeper than the top 1-2 inches. Hence, removing that soil will make a BIG dent in the population. But remove it ALL, and THROW IT AWAY. They are constantly hatching, so keep that in mind!

The gnats can't stick their little egg-laying asses into the soil if it's covered in sand, or fine pebbles. It HURTS. HURT THEM!

Finally, using a natural predator of the fungus gnats will absolutely help reduce, and control the population. When used correctly and consistently for a MINIMUM of 4 weeks, preferably 6 weeks, it will seem like fungus gnats never even existed in your home! But if you don't use it properly, and don't treat EVERY plant, EVERY time, at THE SAME time, for at LEAST 4 weeks, you might as well take the money you would have spent on the predatory bugs, and send it to us, and we'll come out and do it for you! The predators i am referring to are: Hypoapsis miles and Hypoapsis aculeifer, predatory mites that attack and consume the larvae of the gnats, and finally, my personal favorite- Bacillus thuringiensis var. israelensis, also referred to as BTi. BTi is a bacterium that kills their larvae and disrupts the life cycle. This works very well, especially when used in conjunction with the other 3 steps.

Using yellow sticky traps will allow you to monitor the infestation, and isn't helpful in any other way. The adults that are trapped on them have generally already laid their hundreds of eggs by the time they are stuck. But if you are replacing the traps frequently, you should begin to notice the numbers of adult gnats declining- if you're performing the steps properly!


In summary-

Fungus Gnats, while an annoying pest, for sure, are not the end of the world.

They are there from over-watering your plants.

They can eventually cause some damage the plants, but mainly the plant damage is coming from the over-watering.

They can be controlled (if not eliminated) by diligently following a series of actions which control their population very well when properly followed.

If you're not of the mind to perform all of these yourself, you can also call a professional to come out and treat them for you. We understand that not everyone has the time (or patience!) to deal with this type of thing, which is why we also offer this service.

We have successfully treated (and controlled) dozens of our customers' plants for fungus gnats. We have received many relieved smiles and warm thanks from these customers, who were nearly going crazy from the bugs, and figuring out the plethora of crazy, DIY Internet remedies.

We know that the annoyance level with these pests is high, and we'd love to help you get back your sanity by coming out and controlling your gnat population. The service is not very expensive, either. Your peace of mind shouldn't come with a high price tag, in our opinion!


Thank you so much for reading!
Hopefully, you took something away from this post that can help you become a better plant parent, or perhaps you learned something new about caring for your plants.
That is always my goal- To share my personal experiences with other plant people, with the hope that it helps someone in some way, either by trying a different way to do things, and getting a different result, or simply by providing a different perspective, so that someone looks at a situation differently and figures out another successful method on their own.
There are multiple ways to grow plants successfully, and sometimes, what is considered successful to one person, may not be to another person. In the big picture, I believe that all of our experiences with plants should be positive, even if one of them dies. If we take that event, learn from it, and do things differently next time, to a better outcome, that's the goal.
A 'learning experience' is the best thing to come out of a 'negative experience'.
There's no doubt about the therapeutic benefits that come from having plants in the home, and both physical and mental health improvements that occur by keeping plants in the home, it would be a shame for it to become so stressful that they actually cause strife. During the COVID-19 pandemic, there have been a lot of people turning to plants as a way to deal with the daily stresses of the world we live in. Some have jumped in so far, so fast, that they are feeling overwhelmed trying to care for them. If this is happening to you, please reach out to me, and I will do everything I can to help you.
As always, if you have had differing or similar experiences, please comment below, and share them, as I always enjoy hearing other's experiences. If you find any information that I posted that is incorrect, or nonfactual, please also comment below or reach out to me directly. These blog posts are written from my personal experiences, as well as experiences others have shared with me, but, as we are human, so it is possible to make mistakes. Just let me know, so that I can correct and learn from them.
Stay Safe & Be Healthy.

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