Failproof Solutions To Sudden Appearance Of Gnats

There are three primary reasons for the sudden appearance of gnats in the house –

  1. Active breeding grounds such as decaying organic wastes
  2. Food wastes
  3. Choked drains

However, many other factors aggravate the gnat infestations, making the gnats appear in the house all of a sudden.

And this guide will reveal those reasons.

With years of experience in studying gnats and their behavior, I can give you the solution to eliminate and prevent these nuisance flies once and for all.

Keep reading to find out.

Sudden Gnat Infestation: Understanding The Causes

Many types of gnats suddenly appear. The most common are fungus gnats, fruit flies, and drain flies.

And each of these pesky flies has their sources active in your home. 

Let’s find out what sources cause the sudden appearance of gnats in the house.

Overwatered Soil of House Plants Causes Fungus Gnats

Overwatered soil beds cause fungus gnats

Did you know that overwatering your houseplants can cause tiny insects called fungus gnats to infest your plants?

The damp soil beds draw fungus gnats to lay eggs on them. 

Moist soils develop molds that are food sources for the fungus gnat larvae that hatch from the eggs. 

The larvae also feed on the plants’ root hair, making the fungus gnat larvae a harmful pest for tiny plants, especially seedlings.

A female fungus gnat can lay up to 100 eggs. The fast maturity period from egg to adult worsens the matter, leading to a sudden appearance of fungus gnats in the house. 

Overripe And Rotting Fruits And Vegetables Draw Fruit Flies

Overripe fruits draw gnats such as fruit flies

Fruit flies can easily pick up the rotting and overripe fruits in the kitchen from a distance. The fruit smell attracts them.

Undisposed and accumulated food wastes in the kitchen trash cans also emit an odor that draws fruit flies.

Fruit flies fly in through the open windows to feed on these fruits and lay eggs in them. 

But these rotting fruits are not the only things where fruit flies will lay eggs.

These small flies will get inside the drains and garbage disposals to lay their eggs. 

The fruit fly larvae, also known as maggots, feed on the wastes till they mature into adult flies.

End result? A sudden appearance of fruit flies and active sources of fruit fly infestation in the house!

Choked Drains Are Secret Breeding Grounds For Drain Flies

Choked drains cause drain flies appear suddenly

The sludge choking the kitchen sink and bathroom drains is a hidden breeding ground for drain flies.

These slimes are food sources for the drain flies’ larvae, also known as drain worms. 

Homes with drainage issues, faulty sewer systems, and stagnant water always face the onslaught of drain flies because these flies breed in these areas.

The larvae mature into adult drain flies, and they pop out from the drain holes in large numbers. 

That’s why you notice drain flies like tiny black specks on bathroom walls, kitchen walls, and sinks. 

Moisture Issues In The House Attract Gnats

Gnats are moisture bugs. Moist areas in the house will always draw gnats outdoors.

Leaking pipes, plumbing issues, and broken sewer lines create damp environments that lure the gnats indoors.

These flies will breed in damp areas near the leakages.

When the infestation spreads, it appears in areas such as bedrooms with no moisture and food waste.

The worst part is that excess moisture spreads through the walls and causes cracks. These cracks accumulate debris, making the walls egg-laying grounds for gnats.

Outdoor Gnat Infestations Push Gnats Indoors

Outdoor gnat infestations cause gnats indoors

Outdoors, gnats breed in decomposing organic matter such as foliage and mulch. They also lay eggs in the waste in garbage disposals and compost bins.

When their population explodes outdoors, they’re bound to fly inside the house through the windows.

Immediate Actions To Get Rid Of Gnats In The House

Your first impulse might be to use fly spray to eliminate gnats. Well, it works, mainly when you use pyrethrin-based spray.

However, fogger sprays only eliminate the symptoms, not the cause.

For a permanent solution to the gnat problem, follow the steps below.

Dispose Rotting Food, Overripe Fruits, And Clean Your Kitchen

Ripe and rotting fruits draw gnats

Rotting food wastes and overripe fruits and vegetables in the open or trash cans attract fruit flies, fungus gnats, and phorid flies.

Dispose of these attractions and follow a proper cleaning schedule to avoid piling waste problems in the kitchen and home.

Fix Leaky Pipes And Remove Stagnant Water

Leaky pipes create moisture in the house. And moisture attracts gnats.

Water dripping from drainpipes and faucets in areas like the bathroom and basement creates stagnant water, which aggravates the moisture issue in the house.

So, fix water leakages or any other plumbing issues creating damp areas in the house.

Treat The Houseplant Soil To Kill Fungus Gnat Eggs And Larvae

The overwatered soil beds of indoor potted plants attract fungus gnats. They lay eggs on them.

So, treat the houseplant soil with 3% hydrogen peroxide solution and water.

Drench the soil with a mixture and let the mixture sit for a few hours.

The mixture kills the fungus gnat eggs and their larvae. It also removes the molds and fungi that form on the soil’s layer, thereby removing the food sources of the larvae.

And hydrogen peroxide is safe for plants.

However, it is best to remove the upper soil layer and replace it with fresh potting soil once all the larvae and eggs are dead.

And refrain from overwatering your plants.

Treat The Drains To Kill Eggs And Larvae In The Sludge

Clean Sink Drains To Remove Gnat Eggs And Larvae

The sludge choking the drains is hidden breeding grounds for gnats like drain flies.

Clean the drains with a drain cleaner. Or pour a mixture of hot water, baking soda, and white vinegar into the sink drains and shower drain.

Cleaning the drains will kill gnat larvae and eggs in the drain sludge.

Do not use bleach to clean the drains. Bleach is harmful to humans. It erodes the drains from the inside and kills the beneficial bacteria and enzymes in the drains that help break down waste.

Apple Cider Vinegar Trap To Lure And Trap Gnats

Apple Cider Vinegar Trap For Gnats

You can make a homemade trap to lure and kill gnats by preparing a trap with the help of apple cider vinegar and dish soap.

Take a shallow pan or a bowl. Fill it half with apple cider vinegar. Add a few drops of dish soap and stir the mixture well.

Cover the pan with a plastic wrap and affix it with a rubber band. Poke a few holes in the plastic wrap.

Your gnat trap is ready. Keep the trap where you’ve noticed intense gnat activity.

The fruity smell of apple cider vinegar will attract the gnats.

The gnats will try to access the mixture by sneaking in through the holes in the wrap. But the dense dish soap will make the gnats stick and drown.

Instead of vinegar, you can use overripe fruit such as banana or apple.

Let the trap remain for 24 hours before you dispose of the mixture with gnats the following day.

You can also use a ripe fruit, such as a banana, in the dish soap trap. 

There are also yellow sticky fly traps that are readily available. 

Keep them on the potting soil of indoor plants, underneath sinks, and where you’ve noticed gnat swarms in the house.

Ensure Proper Ventilation In The House

Poor ventilation in bathrooms and kitchens with high water usage creates condensation.

That leads to a spike in the moisture levels and draws gnats.

So, ensure that there is proper ventilation. Or install an exhaust fan in damp areas like the bathroom to keep it dry and adequately ventilated.

Installing a dehumidifier in the house also helps keep the moisture levels down.

Seal Entry Points To Prevent Gnats From Entering Homes

The cracks on the windowsills and walls are the entry points for gnats and many household pests.

These tiny insects can easily crawl through them and invade your home. That’s one of the ways how flies invade homes despite closed windows.

Seal those cracks with a quality sealant such as silicone-based sealant or polyurethane sealant. These sealants are strong and waterproof. And bugs can’t chew through them.

Hire Professional Pest Controller For Persistent Gnat Problems

If gnats are returning despite your best efforts, you still need to remove the primary source of gnats that are still active on your property.

In that case, hiring a professional to do the job is always best.


You covered a lot of ground in this guide. The success of your fight against gnats depends on removing their sources and preventing them from returning.

Gnats seem invincible when they suddenly appear. But they’re not.

With a bit of understanding of their infestation habits, the things that draw them, and the places where they lay eggs, you can win the battle against gnats. 

So, gear up, follow the steps in this guide, and reclaim your home from these pesky invaders.

Frequently Asked Questions

Do Gnats Bite?

Household gnats such as fungus gnats, phorid flies, drain flies, and fruit flies don’t bite.

However, biting gnats such as biting midges, also known as no see ums, and black flies bite and feed on human blood. These biting gnats are occasional home invaders too.

Do Gnats Spread Diseases?

No, gnats don’t spread diseases, even the ones that bite.

However, gnats can cause pink eye (conjunctivitis). Gnats follow humans and they can bombard themselves onto human face.

While doing so, they can spread the bacteria that causes pink eye.

Do Gnats Die In Winter?

Yes, gnats die off in the winter months. But they can remain active year-round in a heated home during winters with their sources and breeding grounds still active.

So, only spraying doesn’t work. You need to remove the sources of gnats, too, to eliminate them.

At times, you’ll notice sudden appearance of dead flies in the house during winter and spring.

Those are not gnats. They’re different fly species known as cluster flies.

Do Gnats Contaminate Food?

Drain flies and phorid flies live and breed in damp organic wastes. So, they can always have wastes stuck with their bodies.

When they sit on food, they can transfer these wastes to your food. You may fall ill if you consume that food.

Also, fruit flies can lay eggs in the ripe fruits. These eggs produce maggots, which feed on the fruits from the inside.

Can Gnats Lay Eggs In kitchen Appliances?

Yes, gnats are infamous for laying eggs in appliances that are moist from the inside and have food wastes.

Dishwashers and coffeemakers are easy targets for gnats, especially for fruit flies and drain flies.

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