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  • Writer's pictureAll Things Pest Control

How To Prevent Houseplant Gnats.

Updated: Mar 11, 2022

Whether it be the kitchen corner that needed brightening up with Bunnings Monstera, the hanging space above the bath filled with a cascading Pothos from the local nursery or the sunroom of the old Queenslander filled to the brim with an variety of re-potted plant clippings from friends. Let's face it, everyone loves a plant in their home!

With pot plants comes moisture, organic material and the dreaded Gnat.

It starts with one or two and before you know it, it's an annoying problem that can snowball quickly to your houseplants demise.

What are Gnats?

Gnat is a broad term used to name a variety of tiny flying insect that are usually no larger than a few grains of salt.

There are many types of ‘Gnat’ that all fall under the tiny flying insect suborder Nematocera.

There are stinging and non-stinging varieties with the most common Gnat in our homes (and the ones we are talking about today) being the Fungus Gnat.

Tiny flying Gnats on blurred green background
Similar to tiny weak flying mosquitoes, Fungus Gnats can be a real pest around your home.
Fungus Gnat life cycle
Fungus Gnats are short lived but breed rapidly.

Fungus Gnats, not to be confused with Drain flies, are short lived flies that are similar in appearance to a baby mosquito. They feed mostly feed on fungi growing in soil.

They also aid in decomposition of organic matter, making your fruit bowl and bin a perfect location to thrive in.

Fungus Gnats carry many plant diseases and can strike fear into rare plant collectors due to the unseen larva feasting on tiny plant roots and weakening the plant.

How do I Identify Gnats in my house?

Besides the obvious cloud of irritating, tiny flying insects when you water your houseplants, on closer inspection you can find them walking rapidly over plants soil areas, foliage, fruit bowls or bins.

Gnats are considered weak flyers. While not dangerous to humans, they can be quite unappealing in the home and annoying by flying into their faces, eyes and noses of people.

A closeup of an adult Gnat. 2 Clear wings with 'Y' shaped lines, long legs similar to a mosquito and 2 long segmented antennae.
Adult Gnat: 2 Clear wings with 'Y' shaped lines, long legs similar to a mosquito and 2 long segmented antenna.

Where are they coming from?

Usually, they come in the soil of a newly purchased plant, in a bag of potting mix, or from an open window or plant that was brought in from outside.

It only takes one plant and the right conditions before your entire population of houseplants are affected so if you notice a plant with Gnats, consider moving the problem outside for treatment.

How do I stop Gnats?

  • Don't overwater your plants. Let the soil dry out between watering and empty any stagnant water sitting in a pots saucer.

  • Trim your plants. Remove dead or dying foliage in and around your plants. This removes the decomposing organic material the Gnats are attracted to.

  • Create a soil barrier. Add a thick layer of horticultural sand, gravel or steel wool around the base of your plant.

The abrasiveness of these materials can assist with preventing the gnat larva from hatching and coming to the surface or adults laying eggs in the soil.

  • Don't leave food out. This means washing your dirty dishes and drinking glasses as soon as possible. Even a slight hint of juice, wine, or sauce will attract Gnats.

  • Get rid of damp areas. Fix your leaking pipes under the sink. If there is condensation on the pipes, insulate it by getting a foam insulator. Keep the drip tray of the coffee machine clean. Excess water hidden & coffee grinds beneath the tray is a perfect location for gnats to enjoy.

  • Cover your kitchen bin. Remove rubbish out as often as possible. Stinky bins are a haven not only for gnats, but other creepy crawlies as well such as Cockroaches and Ants.

A white humidifier blowing a white cloud into the air in front of a blurred green plant
Humidifiers help create the perfect environment for moisture seeking Gnats
  • Limit the use of your humidifier. While great for those humidity loving plants, a humidifier provides a wonderful environment for Gnats. Try avoiding it until you have eradicated your Gnat issue.

If possible, move your humidity loving plants to a room like your bathroom to make use of the humidity there.

  • Gnat traps. Invest in sticky traps or make your own and place around areas Gnats are present.

  • Cider-vinegar traps: Simple and effective, cider-vinegar traps consist of a shallow container with a small amount of apple cider vinegar, water, and liquid dish soap. The cider attracts the adult Gnats and the dish soap traps them in the liquid. These traps will need to be around for several weeks to ensure all the freshly hatched Gnats are caught too. Remove and bag up the traps and replace as needed.

  • Neem Oil. Apply Neem oil to soil areas in conjunction with traps. This again, will need to be maintained for a several weeks to ensure the Gnat lifecycle is broken.

  • Replace your soil. In a significant infestation when you have had no reprieve trying the above options, consider repotting your plants with fresh soil. Ensure you bag up the infested soil and place in your wheelie bin. Do not place in the compost!

An A frame shelf with a variety of pots in saucers
Keep an eye on new plants or ones brought in from outside as they can quickly spread Gnats to others.

In commercial or heavily infested areas, consider a pest control treatment.

A misting treatment for Gnats can be conducted by a licenced pest control service such as All Things Pest Control. It involves a mist application to problem areas and is only toxic to Gnats themselves. Once dry, it is perfectly safe for humans and their pets to return. This treatment will need to be re-done in 1 weeks time to ensure freshly hatched Gnats are taken care of.

Summing it up.

Treating for a Gnat infestation takes time and patience. By checking your plants on a regular basis and making simple changes to your plant care routine you can eradicate and prevent a Gnat infestation in your home.

Are you having issues with Gnats or other flying insects? Contact the team at All Things Pest Control in Mackay to discuss your best course of action.



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