How Do You Get Rid of Flies in Potted Plants

So you have a fly problem, now you want to get rid of flies in potted plants.

It can seem unusual at first, but it’s a common problem for many plant owners. Having a small infestation of flies in your potted plants can be annoying and worrisome.

Closeup of fungus gnats being stuck to yellow sticky tape
Yellow sticky tape catching Fungus Gnats | Akchamczuk-DepositPhotos

Not only do flies irritate you in your home, but they can also be quite damaging to your plants.

Thankfully, there are a few ways to help eliminate flies in potted plants to ensure your plants remain healthy and your home stays free of pests.

Why Do Flies Flock to Your Potted Plants?

There are a few different species of flies that breed and infest potted plants. For the sake of brevity, we will be covering the most common fly in potted plants: fungus gnats (Sciaridae).

Fungus gnats are small flies with round wings, greyish color. They can resemble mosquitoes in their adult stage of life, though they are much smaller.

Moist soil draws fungus gnats to the plentiful amounts of organic decomposition. The soil makes potted plants an ideal home for gnats due to the pot’s moisture and organic material. Also, the pot itself offers more protection from other pests.

These flies are inclined to move towards the light, making them quick to identify. If you see small gnats flying around the windows closest to your houseplants. This could indicate fungus gnats.

What Damage Do Flies Cause?

Fungus gnats do not typically damage plants. In large numbers, gnat larvae can cause root rot and can break down the plant.

How? The larvae attach to the roots and stunt plant growth by preventing the root from expanding. This naturally cuts off the plant’s ability to collect water.

In the gnats early life stages, they may eat the roots for nourishment, speeding up the problem of rotting.

Related: Getting Rid of Gnats With – Cinnamon | Dawn Dish Soap

How To Control Flies in Your Potted Plants

When controlling flies in potted plants, Clemson.edu suggests that the best method of protecting plants from flies is through – prevention.

But, if you already struggle with fungus gnats, there are a few ways to combat the infestation with chemical and natural methods.

Control Fungus Gnats Naturally

Natural remedies work wonders on eliminating fungus gnats from your plants. There are many different solutions. Natural methods often get rid of the flies better than chemical insecticide solutions.

Clean the Roots

One of the simplest methods to combat fungus gnats is by clearing out their larvae. An easy way is to pull your plant out of its pot and clean off the soil.

Clean the roots with water. Be gentle! Do your best to clean all of the larvae and eggs attached to the plant’s roots.

Dump the infested soil and clean out the pot with soap and water. Repot your plant with fresh soil. Watch the plant for a few weeks to see if it needs another cleaning.

Expect some “Transplant Shock”!

Dry Out the Soil

The best time to use this method is in the winter when your plant enters its dormant state.

Fungus gnats need moist soil for their larvae to survive. Allow the soil to dry out for a few days. The lack of moisture will kill off any larvae inside the pot and prevent fungus gnats from viewing your potted plant as the perfect home.

Insecticidal Spray

If your plants still face problems with fungus gnats, make a proven insecticidal spray to use on the plant’s roots.

Mix two tablespoons of mild soap (Dawn dish soap or Castile soap) to a gallon of water. Pour the solution into a spray bottle to spray the soil and plants.

Neem Oil Drench

Neem oil is a “natural insecticide” useful in combating various plant insect pests.

For more, read our tips on How To Apply Neem Oil to Soil

Chemical Controls

Fungus gnats are easy to control and get rid of. Chemical solutions are a last resort. But, if you find yourself with a large infestation, there are a few insecticides that work.

Insecticides

Bacillus thuringiensis israelensis (Bti) is a bacterium used to control the larval stage of mosquitoes, fungus gnats, and black fly.

Bti is safe for use around mammals, birds, fish and amphibians.

Once ingested the bacterium produces crystalline toxins disrupting the digestive system of the fungus gnat. This results in stopping development and kills the larvae pest before reaching adulthood.

Steinernema feltiae are parasitic nematodes. These non-segmented, microscopic worms destroy insects in soil-borne stages from the inside out.

These nematodes kill 100’s of ground maturing insects before they reach adult stage. They include:

  • Borers
  • Fleas
  • Fungus gnats
  • Japanese beetles
  • Weevils

… and more

When released into the soil, the nematodes enter the pests through various orifices. The bacterium released by the nematodes kills the pests in a day or two.

The nematodes feed on the dead remains, and continue to multiply. After exhausting the food supply they leave and move to another food source.

These nematodes do not prey on beneficial insects such as ladybugs and earthworms. The bacterium they produce is harmless to humans and plants.

This can be a costly option but a useful solution depending upon the infestation level. Either way, figuring out how to get rid of flies in potted plants is necessary to keep your home (and foliage) healthy.

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