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How Do I Get Rid of Fungus Gnats?

One of the most common intruders that can infest your indoor houseplants is known as the fungus gnat, Here's how to get rid of them.
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Blessed be our lovely houseplants, as they have the special gift of mesmerizing any surroundings and making us feel like natural-born caregivers! We, gardeners, cannot help but adore our baby plants even with their occasional rebellious teenage phases. But there comes a moment in our lives when our companions are bothered by certain curious, many-legged, and annoying intruders. Our duty here as caregivers is to provide our helpless plants with the best possible support and, although it is not always easy, we have to do our best!

You might think that if you grow your plants indoors there are fewer chances of pests to infest them. And you are partially right! However, this should not prevent you from paying a little extra attention to your houseplants. Pests are full of surprises, so you might want to check your green babies once in a while to prevent any possible irreversible damage.

One of the most common intruders that can infest your indoor houseplants is known as the fungus gnat. Although fungus gnats are often considered minor and less harmful houseplant pests. If not taken care of, they can become a major problem pretty quickly, especially if the infestation goes beyond control. But do not worry, things are not as catastrophic as they sound! In this article, we will tell you everything you need to know about fungus gnats and how you can prevent or get rid of these episodic pests.

What Are Fungus Gnats and How to Identify Them

Fungus gnats are fruit fly-sized insects that can be primarily found around houseplants grown indoors. The adult fungus gnats can be easily distinguished from other pests as they have a grayish-black body color and see-through gray wings.

They have quite long antennae and legs that resemble those of mosquitoes, but fungus gnats are much smaller in size. The larvae of these pests are described as tiny, having a black-colored head, and a thin, white-tinted, or see-through body.

Fungus Gnat
Fungus Gnat

Since these pests cannot bite nor spread any diseases, they are completely harmless to humans when getting in contact with them. But! Both larval and adult stages of fungus gnats can cause big issues for your charming houseplants. However, fungus gnats larvae are known for their ability to only damage young plants, cuttings, or seedlings.

Mature fungus gnats live for about one week or so, a period in which these pests lay up to 300 eggs in damp soil that is rich in nutrients and organic matter. Although these intruders can affect the overall health of many humidity-loving houseplants, some species are especially prone to injury.

A few examples of the most common plants infested by fungus gnats include:

If you want to identify these pests properly, look carefully at the pots of your houseplants. Fungus gnats love to spend most of their time on the surface of the potting soil, near drainage holes, or flying around the margins of the pots as well. They are somehow slow-fliers, so it can be very easy to catch and remove them from your plants with bare hands.

Fungus Gnats Damage and Signs of Infestation

Fungus gnats have a higher chance to infest your plants if you grow them in a location with a lot of humidity and moisture and little ventilation. These pests are usually attracted to damp potting substrates, so you must watch out for infestation signs on plants that require watering more often than others.

When they are seen in small numbers, you should know that fungus gnats are more annoying than they are damaging. In general, the adult fungus gnats do not actually harm plants if they are kept under control. But, sometimes, their population can get out of control and the larvae of these pests may start feeding on your plants’ roots causing visible damage. And this is not exactly what we would want, especially on younger plants that have delicate roots.

If your plants are infested by fungus gnats, they will show obvious signs that are similar to those of other root-related issues (root rot, for example). With that in mind, you should inspect your houseplants regularly to make sure you take action in the early stage of infestation.

At first, the lower leaves of your plants will turn yellow and eventually drop off with time. You may also notice some major changes in the growth habit of your plants, such as a slower growth or even the lack of it. In more advanced forms of infestation, the wilting of the entire foliage can occur. If the roots are extremely damaged, your houseplants can do nothing but die.

How to Prevent Fungus Gnats Infestations

Of course, there are always solutions to prevent any future infestations and we’re happy to share some tips and tricks with you. These techniques are not difficult to implement, so you can start applying them even if you are not particularly experienced in the gardening world.

Remember: your baby plants count on you to protect them from any dangerous situation!

  1. Maintain the potting soil dry

Because fungus gnats love lots of moisture and humidity, you can try another watering routine. Make sure you always check the soil in-between waterings to avoid soggy conditions. Provide your plants with water only when the top one or two inches (2.5-5 cm) of soil have dried out to slow down or even stop the infestation. If the soil is dry on the surface, fungus gnats will not lay their eggs in the future.

  1. Cover the drainage holes of the pots

As mentioned above, fungus gnats can be found occasionally in the proximity of drainage holes where they may start their egg-laying process. If you notice any signs of infestation, you can cover the drainage holes with a piece of any type of fabric to obstruct their way in or out. This method should also allow the water to pass through the fabric, so do not use a material that is too thick.

  1. Use mosquito dunks and beneficial bacteria

Mosquito dunks are products formed of dry pellets that contain a specific type of bacteria known as Bacillus thuringiensis subsp. isrealensis. This beneficial bacteria is often used to combat and kill the larvae of many species of flying insects, such as fruit flies, mosquitoes, or fungus gnats. The best part of using mosquito dunks is that they can be reused.

This method consists of filling up a bowl with clean water and placing the mosquito dunk in it. For optimal results, it is suggested you break up the product a bit before tossing it in the water and let it soak overnight. After you’ve completed this step, remove the dunk from the water, and use the prepared mixture to treat your infested houseplants.

Control and Get Rid of Fungus Gnats

Due to their slow-flying habit, adult fungus gnats are fairly easy to catch and get rid of. The secret to keeping the infestation under control is consistency. The mature population of fungus gnats comes in cycles, so you need to refresh or change the traps you are using regularly. Here are some tricks that will help you get rid of fungus gnats infestations and you can also use them in combinations for the best results.

  1. Yellow Sticky Traps

These traps come along with a yellow card that is entirely covered in a sticky adhesive. This method is very effective if you cut the sticky traps in small squares and place them just above the potting soil. It is said that fungus gnats are attracted to the color yellow, so they will crawl or fly onto the cards and get trapped.

yellow sticky trap
Yellow sticky trap
  1. Flypaper Ribbons

These traps are mostly seen in horse barns to catch all types of outdoor flies, but they are also used by many gardeners to catch fungus gnats. Flypaper ribbons will kill fungus gnats pretty fast, but be careful where you are placing them in the process. They can get stuck easily to many unwanted things including plants, hair, furniture, and other stuff.

  1. Apple Cider Vinegar Traps

You can make your own trap by filling a container with equal parts of apple cider vinegar and water. Add a few drops of liquid dish soap into the blend and stir it gently until combined. This trap can be placed near the base of the infested houseplant or, better, on top of the soil. Check your plants once every few days to refresh them with a new mixture.

  1. Flying Insect Killer

If you want to opt for a more organic alternative, the Flying Insect Killer is a combination of peppermint, sesame oils, and cinnamon. It is a very popular product used to get rid of fungus gnats and many other species of insects that gather around windows.

In Conclusion

Having a collection of eye-catching houseplants and caring for them is a truly unique experience. Even if our babies can be bothered sometimes by nasty intruders, there will always be some solutions to our problems around the corner. If we constantly pay attention to our plants, pests like fungus gnats will seem harmless in the future.

Have you ever had to deal with a fungus gnat infestation? Share your experience in the comments below!

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Miruna is an experienced content writer with a passion for gardening. She is the proud owner of an outdoor rose garden and an indoor collection of tiny succulents. She bought her first succulent 10 years ago - an adorable Echeveria Setosa. Now she owns more than 100 succulents and cacti of different colors, shapes, and sizes. Miruna is a versatile writer and, as you might have guessed, her favorite topic is gardening. Contact miruna@gardenbeast.com

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