Where Do Fungus Gnats Lay Eggs Indoors And Outdoors?

Can fungus gnats lay eggs anywhere? Certainly not.

These pesky flies have their go-to breeding sources both indoors and outdoors. 

Knowing those sources and treating them makes a significant impact on eliminating fungus gnat infestations.

This guide will reveal three places where fungus gnats lay eggs.

You’ll also find two secret egg-laying grounds for fungus gnats that many homeowners today don’t know.

Plus, I’ll also give you the proven hacks to treat these areas to remove the eggs and fungus gnat larvae.

Keep reading.

Usual Egg-Laying Locations Of Fungus Gnats

Adult fungus gnats lay eggs in –

  1. Wet soil surface of potted plants indoors and outdoors
  2. Decaying organic matter
  3. Inside drains

Fungus gnats’ survival and biological needs are dependent on these areas. That’s why they lay eggs on them. 

Let’s dive into these breeding grounds and discover why fungus gnats lay eggs in them.

Moist Soil

Wet or moist soil of potted plants indoors and outdoors has molds and fungi that are food sources for the fungus gnat larvae.

So, the adult gnats lay eggs in moist soil to give their larvae direct access to their food sources.

The larvae feed on the fungi until they reach the pupal stage before emerging as adult fungus gnats ready to breed.

Females lay eggs in the potting soil of indoor plants, leading to fungus gnat infestations in the house.

Decaying Organic Matter

Rotting debris such as leaf litter, foliage, rotting mulch beds, and food wastes release carbon dioxide and methane. These gases draw fungus gnats.

When fungus gnats pick up these gases, they know that there’s rotting debris with molds and fungi where their larvae have maximum chances of survival.

That’s why gnats are attracted to humans because humans, too, exhale carbon dioxide, which tricks them into thinking that they’re at a breeding source.


The gunk blocking the drains is egg-laying grounds for fungus gnats and other gnats in the house, like drain flies, phorid flies, and fruit flies.

The larvae in the drains feed on the molds that form on the wastes, choking the drains.

When these larvae mature into adult fungus gnats, they pop out of the drain holes and appear as black dots on kitchen sinks, bathroom sinks, and the floor and walls of bathrooms and kitchens.

And they don’t take long to spread in other areas of your home, such as your bedroom, where there’s no waste.

The above are the three common areas where fungus gnats can lay eggs. 

But these small flies can lay eggs in your house in two more hidden places.

Fungus Gnats Eggs In Wall Voids

Fungus gnats can also lay eggs in the cracks and voids on the walls.

These cracks can accumulate organic debris. And the dampness in the walls will make the organic wastes in the wall voids moist. 

That will undoubtedly draw gnats’ attention, causing them to lay eggs in those cracks. 

So, repairing any wall damage and ensuring no dampness in the walls are vital to keeping gnats and many other bugs away from walls and ceilings.

Fungus Gnats Eggs In Electrical Appliances

Electrical appliances such as dishwashers and coffee makers have food waste in them. 

And the food waste stuck in these appliances is always moist from the inside because of the nature of these appliances.

So, fungus gnats will sneak inside the appliances to lay their eggs, leading to fungus gnat larvae in them. 

That’s why cleaning the appliances, especially the dishwasher, is vital to remove the house’s hidden sources of fungus gnats.

Fungus Gnats Eggs Description

Fungus gnats’ eggs are oval and shiny white. The eggs are 0.5 – 1 mm in size and semi-transparent. Their tiny eggs are impossible to detect with the naked eye.

Where do fungus gnats lay eggs
High Resolution Image of Fungus Gnat Eggs

The eggs hatch in 4 to 6 days, depending on the moisture levels and temperature.

Fungus gnat larvae that hatch out of these eggs are mostly harmless. But they bring some risks to the plants.

Fungus Gnat Larvae Appearance

Fungus gnat larvae are tiny white, legless worms 4-5.5 mm in size. They have a little blackish head that appears as a dot.

The larvae feed on the molds that form on the moist organic debris and wet soil.

Fungus Gnat Larvae
Fungus Gnat Larvae

The fungus gnat larvae also feed on the root hairs on the plant roots of young plants and seedlings.

Fungus gnats also spread pythium, a plant pathogen that harms seedlings.

So, too many of these larvae are risky for your plant’s health.

Fungus Gnat Life cycle

There are four stages of the fungus gnats’ life cycle. Each stage has a particular number of days associated with it –

  1. Egg stage – 4 to 6 days
  2. Larval stages – 5 days
  3. Pupa stage – 5 to 6 days
  4. Adult gnats – 7 days

As I mentioned, the eggs hatch after 4 to 6 days.

The larval stage lasts for 5 days. During this period, the fungus gnat larvae feed on the molds and fungi in their breeding grounds.

After 5 days, the larvae spin a cocoon to lock themselves for 5 to 6 days. This cocoon stage is known as the pupae stage.

Adult gnats emerge out of the cocoons. Fungus gnats’ have a short lifespan and live for only 7 days.

During this period of 7 days, fungus gnat adults breed and lay eggs.

Treating Fungus Gnats Breeding Grounds

Female fungus gnats lay 100-150 eggs, which they pack in clusters and place on the plant’s stem, in damp soil, and moist organic debris.

These eggs hatch within 4 to 6 days, triggering a potential severe fungus gnat infestation.

Stopping adult gnats from entering the house and discouraging them from laying eggs are vital to prevent indoor and outdoor infestations.

And you can do it in a lot of ways.

The first is by sealing the cracks on the windowsills and installing meshed window screens to prevent these flies from entering the house.

Fungus gnats are attracted to light and they gather near windows before they sneak inside through the windowsill cracks.

Removing decaying organic matter and food waste from your yard and home eliminates the most common potential breeding ground for gnats.

Treating the potting soil with hydrogen peroxide or Epsom salt kills the eggs, larvae, and pupae. 

But you shouldn’t limit the soil treatment only for outdoor plants. You must treat the potting soil of indoor plants, too.

Refrain from overwatering the soil beds. Keeping the soil dry and fresh is essential for gnat control.

Keeping yellow sticky traps at places with high gnat activity, attracting beneficial insects such as ladybugs, treating infested plants with plant-safe sprays, and controlling excess moisture reduces fungus gnat populations in homes.

Apple cider vinegar traps work great to lure fungus gnats and trap them. 

You can prepare it by mixing apple cider vinegar with liquid dish soap and wrapping the bowl with a plastic wrap.

Poke a few holes in the plastic wrap and keep it in the places where fungus gnats tend to lay eggs.

The fruity smell of the vinegar will attract the gnats. But when they sneak inside the trap through the holes in the wrap, they’ll drown in the mixture because of viscous dish soap.


Fungus gnats lay eggs in damp soil and organic debris. They hatch into larvae, then adult gnats, causing sudden nuisance flies

Though not harmful, fungus gnats can be irritating. 

It’s vital to treat the egg-laying grounds of fungus gnats regularly to prevent a fungus gnat infestation.

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