Home Remedy for Fungus Gnats

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Plant pests are one of the most common types of household infestation.

Look just about anywhere online, and you’ll find a small library on how to deal with aphidsmealybugsplant scales, or spider mites.

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But there are one species that tends to be more common than all the above yet is addressed far less often.

This is the infamous fungus gnat.

The term fungus gnat actually applies to a whole host of species in the Sciaroidea superfamily.



Fungus gnats are common indoor pests that resemble mosquitoes, except they don’t bite, and can often be found around plants.

They are fairly tiny insects. They can be identified by their narrow legs, light gray or clear wings, and segmented antennae larger than their heads.

As adult gnats, they’re completely harmless to everything but your sanity. 

Gnats prefer to lay their eggs in damp soil filled with decaying organic matter, which is why they love hanging out in greenhouses and around houseplants.

However, a single female fungus gnat can lay up to 200 eggs during her one-week lifespan, and these eggs hatch into hungry little larvae.

If fungus gnats are a problem around your houseplants, try using a potting mix that doesn’t contain composted ingredients like processed forest products, bark fines, or actual compost.

The larvae are the real problem, as they will often gnaw on plant roots while feeding on fungus and mold.

This damage isn’t usually enough to hurt a plant but can become serious with a large infestation or if the plant is already sick.

As they love fungi, plants suffering from root rot are especially vulnerable.

It’s a sad fact that commercial soils often contain fungus gnats, so it’s important to have solutions ready at all times.

Thankfully, you can effectively combat this pest without the need for harmful chemicals.

If you find a fungus gnat problem, try to quarantine the infected pots away from other houseplants so the problem does not get worse or spread. 

What Are Some Home Remedies Getting Rid Of A Fungus Gnat Infestation?

There are a lot of easy home remedies, most of which require items you probably already have lying around.

A small fungus gnat with translucent blue wings on a wooden surface.Pin
Photo Credit: IG @j.l.perrone

Here are just some of the many quick and easy remedies available:

Steinernema feltiae

This species of beneficial nematode is a great treatment for house plants that need consistently moist soil.

Simply add these natural predators to the damp soil, and they’ll attack by burrowing into the larvae and releasing bacteria that digest the victim from the inside out.

They feed on plant roots, leaves on the soil, and decaying plant materials. 

Cinnamon

This once-expensive spice is a great repellent against many critters and can even kill some pests, such as fungus gnats.

Sprinkle a thin layer of cinnamon on the soil surface.

Not only will this kill the gnat larvae, but it’s also an effective fungicide.

Related: Using Cinnamon For Fungus Gnats

Diatomaceous Earth

Often referred to as simply DE, this remedy is actually the crushed remains of diatom fossils.

Sprinkle a thin layer of Diatomaceous Earth on the soil of potted plants when it’s dry to the touch.

The fragments will cut through a pest’s protective wax coating, and they will slowly dehydrate to death.

You will need to reapply DE every time you water the plant, or it rains, and it’s best to do so every couple of days.

It can take a little while for the DE to eliminate the infestation, but it’s a cheap and highly effective remedy.

Homemade Fly Traps – Apple Cider Vinegar Trap

You’ve probably already made one of these before.

Simply take a 20-ounce soda bottle and cut the top off where it begins to curve, then tape the top upside-down into the bottom.

Fill it with apple cider vinegar and (if you so choose) a few drops of dish liquid.

The gnats (and fruit flies) will fly into the opening and get stuck because they can’t navigate the funnel shape, eventually drowning.

Horticultural Sand

Chances are, you already have some horticultural sand around. Simply apply a thin layer of fine sand over the potting soil, and you are done!  

Unlike the common sand used in sandboxes, horticultural sand is often used as a soil aggregate.

It also happens to work well against fungus gnats. 

Simply add ¼” inch of horticultural sand on top of the soil, and it will discourage the gnats from landing or laying eggs.

If needed, add perlite to your potting mix to help improve drainage, especially if you tend to overwater. 

Hydrogen Peroxide

In the garden, this household and bathroom chemical is extremely useful.

In fact, you should be using part Hydrogen peroxide on indoor plants regularly.

For those who aren’t using peroxide regularly, you can make a surface spray that will kill fungus gnats and their larvae on contact.

Simply take 3 cups of distilled (AKA baby) water and mix in 1 cup of hydrogen peroxide rated at 3% percent or higher strength.

Biological and synthetic insecticide sprays are effective for quick results against fungus gnats, but they are not a long-term solution and are seldom necessary.

Spray the mixture directly onto dry soil and repeat daily until the infestation is gone.

More on: Using Hydrogen Peroxide To Kill Fungus Gnats

The Irish Method

Fungus gnat larvae are an important part of the exosystem since they help control fungus, mold and also break down organic matter.

That’s not to say you want them near your plants, but having this knowledge gives you the means to trick them.

Slice up some raw potato and lay the slices on the infested soil.

The gnats will be attracted to the potato and will burrow up for a bite.

Keep an eye on the slices and replace them as they become infested until all the larvae are gone.

Of course, no true Irishman would waste a good potato like this, but it’s still a great way to slowly extract an early infestation.

Neem Oil

Used as a soil soak, neem oil kills ground-based pests and protects a plant from piercing bugs.

Simply emulsify a gallon of water with 1 teaspoon of Dawn liquid dish soap or pure castile soap, then stir in 2 tablespoons of 100% percent cold-pressed raw neem oil.

Test a small portion of each plant to ensure it isn’t allergic or overly sensitive.

After 24 hours, pour 2 to 4 cups of the mixture per plant around the roots, avoiding splashing on the plant itself.

This treatment can be reapplied every 21 days as a preventative.

Details: Using Neem Oil For Control of Fungus Gnats

The Sticky Trap

One of the easiest methods is to pick up some yellow sticky traps from your local supermarket or hardware store.

Small yellow sticky traps can be cut, placed on wooden stakes, and inserted into pots close to the soil, where adults tend to crawl and fly. 

Since the larvae do the bulk of the damage, it helps to be aware of the fungus gnat’s life cycle. In only three days, the tiny eggs can hatch into larvae in a warm house.  

Adult fungus gnats are attracted to the yellow paper and will quickly get themselves stuck. 

Adult female fungus gnats lay their eggs in organic, moisture-rich environments like potting mix, which hatch into larvae at room temperature in a matter of days.  

 The adults lay their eggs in the soil, and the emerging larvae feed on the soil’s organic material and the plant’s root hairs.

This remedy won’t kill larvae, so you will need to leave the strips up for about a month to get the eggs and larvae when they reach adulthood.

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