What Are Mosquito Dunks – Can You Use Them For Fungus Gnats?

House fungus gnats are tiny bugs that can cause significant problems for indoor plants. Although harmless to humans, their larvae can feed on the plant roots of container plants, causing permanent damage.

While any house plant is potentially at risk, fungus gnats are particularly destructive to spider plants, African violets, geraniums, and peace lilies.

Use Mosquito dunks to control Fungus Gnats Pin

A pest control gadget called a mosquito dunk is one of many methods used to remove fungus gnats from plants.

This is a safe and quick way to control gnat infestations. But it requires a unique technique for the greatest effectiveness.

What Are Fungus Gnats?

You’ve likely seen fungus gnats before, as they’re a prevalent indoor pest.

They’re small, black flies drawn to lights and dampness. You’ll find them near windows, lamps, still or standing water, and houseplants.

Fungus gnats have four development stages:

  • Eggs
  • Larvae
  • Pupae
  • Adults

Adults lay about ten eggs at a time, which hatch after about five days. The larvae have shiny, black heads with a white body.

Furthermore, the Pupae feed voraciously before they emerge as adults. Fungus gnats reproduce quickly, producing many generations every year.

Related: Does Neem Oil Get Rid of Mosquitoes?

Fungus Gnat Damage: What Damage Do Gnats Cause?

It is interesting that adult fungus gnats are harmless. They don’t bother people, pets, or plants.

Yet, fungus gnat larvae are a different issue.

Fungus gnats prefer to deposit their eggs in two to three inches of damp soil. Inside a house, that type of environment is often found the potting mix of a potted plant.

One female fungus gnat alone can produce several generations of offspring each season. This can inundate your plants with larvae.

Fungus gnat larvae feed on the roots and inside stems of most common houseplants. The resulting damage manifests as plant yellowing and slow, stunted growth.

Additionally, adult gnats can spread pathogens from one plant to others, harming all the plants in your house.

Related: Does Cinnamon Help With Fungus Gnats?

How To Control Fungus Gnats?

A fungus gnat outbreak is difficult to stop. The best strategies are prevention and quick action at the first sign of any fungus gnat infestation.


By the time you see fungus gnats, you might already have a problem.

Place sticky notes or strips of tape, sticky side up, around your potted plants. If dead gnats start to appear on the sticky notes, it’s time to take further action. Growers use commercial yellow sticky traps.

Non-Chemical Solutions

First, you’ll want to put in place a few simple techniques for your plants.

Fungus gnats wish to lay their eggs on the moist soil surface, so reduce the amount of water you give your plant as much as possible.

If the top three soil layers remain dry, fungus gnats are unable to lay eggs. In this way, you limit (and cut back) their numbers.

Additionally, cover the drainage holes underneath the flower pots. Although gnats lay most of their eggs near the soil’s top layer, they’ll lay eggs in any soil if necessary.

Block the drainage holes with a synthetic fabric to stop gnats. This still allows water to drain.

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Use A Mosquito Dunk

A mosquito dunk is a simple, effective device used to kill mosquito populations and other pests. Although Mosquito Dunk is a brand, many people refer to all generic equivalents as mosquito dunks, too.

The key active ingredient is a bacteria called Bacillus thuringiensis subspecies israelensis, or BTI.

BTI isn’t a pesticide product.

Instead, it’s a strain of bacteria that functions as a biological mosquito larvicide. This organism naturally kills a pest but leaves the surrounding environment unharmed.

While most biological mosquito control agents take days or weeks to show results, BTI is faster.

Dunks dissolve in water. As they dissolve, they release BTI. It then infects pests, damages them internally, and kills them.

It’s effective on mosquito larvae and other various flying insects, including fungus gnats, and fruit flies.

When killing mosquitoes, place the doughnut-shaped dunk where the larvae live, in bird baths or wherever water collects. Because fungus gnat larvae live in moist potting soil, you need a different approach with the dunk:

  • Break the dunk into a few pieces.
  • Place the pieces into a gallon of water.
  • Let the dunk soak overnight.
  • Remove the dunk from the container of water.
  • Pour the water over the potting medium surface area of your houseplants.

The BTI-infused water will kill any larvae in the soil.

While still watering at minimal levels, use this type of water on all your plants for at least three months. Not only will it remove fungus gnats from your home, but it’s also safe for your plants.

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