Are you plagued by tiny black flying bugs that linger around your indoor plants? If you’re a houseplant parent, you know that fungus gnats can be a real pain. These tiny pests attract moist soil and can quickly damage your plants by feeding on their roots. Fortunately, there are a few easy things that you can do to end your struggle with fungus gnats for good.
What are fungus gnats, and what do they look like?
Fungus gnats are small, tiny flying insects often found near damp areas such as potted plants, kitchen sinks, and bathrooms. These pesky flying critters lay eggs in wet potting soil high in organic matter and decaying plant material.
The larvae of fungus gnats are thin and white, with black heads. They are typically less than 5 mm in length and have slender bodies. Fungus gnats are often mistaken for fruit flies, but they can be distinguished by their long, slender bodies and wings, which are covered in small hairs.
Why are fungus gnats bad for houseplants?
Although they are relatively harmless to humans, they can cause significant damage to plants. The larvae of fungus gnats feed on decaying organic matter in the damp soil. If the gnat larvae are allowed to grow unchecked, they feed on a plant’s root hairs and can start affecting other parts of the plant, like the stem and the leaves closest to the soil surface.
When the roots of plants are damaged significantly, the plant becomes more susceptible to disease. In severe infestations, the damage caused by fungus gnats can result in the death of the plant. That’s why learning to control gnats and kill fungus gnat larvae is essential.
Where do fungus gnats come from?
Fungus gnats are attracted to moisture, so they often invade homes through open doors and windows or cracks in the foundation. Once inside, they lay their eggs in damp areas such as sinks, potted plants, and drains.
Even if fungus gnats get inside your house, they won’t have anywhere to lay eggs as long as you follow some fungus gnat prevention tips, which I’ll explain further in this post.
How to get rid of fungus gnats in houseplants
If you suspect you have a fungus gnat problem, don’t panic. It’s a fairly common problem, and there are several ways to get rid of the little guys. Here are some organic options for getting rid of fungus gnats.
Let the soil dry out before watering it again
One of the easiest ways to eliminate fungus gnats is to let the top inch or two of your plant’s potting mix dry out between waterings. This will make it less attractive to the pests and help prevent them from laying their eggs in the soil. It will also make the environment less hospitable for fungi, and the adult gnats will eventually die off.
One tip to avoid overwatering your indoor plants is to buy a moisture meter to confirm that the potting soil is relatively dry before watering again.
Place sticky tape or fungus gnat traps near the base of indoor plants. These are pretty inexpensive and can be found online or in gardening centers. Yellow sticky traps are one of the most common ways to easily catch fungus gnats to avoid an infestation.
Vinegar traps are another great option – they’re incredibly effective at trapping fungus gnats and fruit flies. Filling a small bowl or jar with vinegar (apple cider vinegar works well for this) or a cheap beer and leaving it out on an open surface near your affected plants might do the trick. Adding a few drops of dish soap into the vinegar traps makes an escape less likely.
Dealing with severe fungus gnat infestations
If yellow sticky cards aren’t taking care of the fungus gnat infestation on your infested plants, it’s time to take more aggressive action.
Use beneficial nematodes to control fungus gnats if you have a severe infestation. These microscopic organisms kill the gnat larvae, preventing them from causing further damage to your plants. It generally takes 24-48 hours for the effects to take place and kill the fungus gnat larvae, but it’s recommended to give a second dose of these beneficial bacteria about a week later just to be sure.
Beneficial nematodes do not threaten humans, pets, or plants; you can buy a packet at a gardening center or online. They’re not as convenient as some other ways to get rid of gnats, but they are a more holistic option that deserves inclusion on this list.
Hydrogen peroxide can also help eliminate gnats without harming your plants. Mix one part 3% hydrogen peroxide to four parts water in a spray bottle, and mist the solution onto the affected area. The hydrogen peroxide will kill the larvae, and the adults will be discouraged from laying eggs in the soil. Spray the affected plant’s leaves and stem to target the adult gnats. For incredibly dense infestations, you can try a plant soak, where you thoroughly saturate your plant’s potting soil with the water + hydrogen peroxide mixture.
For the best results, use a new solution on the soil surface every few times you spray, as the hydrogen peroxide will degrade over time. Hydrogen peroxide treatments may not affect adult fungus gnats if you only spray on the soil surface, but the adults don’t live very long anyway. The solution will slowly kill the fungus gnat larvae and eggs inside your potting soil.
Neem oil comes from the seeds of the neem tree, and it has been used for centuries in India for its myriad benefits. The oil is a natural insecticide, fungicide, and pesticide, making it an ideal choice for those looking to kill fungus gnats. When used as a soil drench, neem oil can help kill larvae before they hatch and is also effective at controlling adult populations.
Use a diluted solution of neem oil and water, and apply it to the soil around your plants. Be sure to give the plants a good watering afterward to help wash away any residual oil. Neem oil is also generally safe for humans and animals.
Repotting with fresh soil
If the infestation is severe and you do not wish to bother with the other options I’ve described, you can repot the plant with a fresh, sterile potting mix. After that, look at the following section about fungus gnat prevention tips to ensure your plants don’t get reinfested.
Fungus gnat prevention tips
You can do a few different things to prevent fungus gnats from taking hold of your beloved plants. A little prevention is well worth the effort! You can avoid a severe fungus gnat infestation by taking these precautions.
- Avoid overwatering your plants. Allowing the top layer of soil to dry out between waterings will also help to keep fungus gnats at bay. Fungus gnats lay eggs in damp soil, so opting to water your indoor plants deeper but less often is an excellent prevention method. There’s nothing less attractive to fungus gnats than dry soil!
- Use plant pots that drain effectively. Fungus gnats thrive in moist environments, so keeping the soil dry will help to discourage them. Sitting water can be a problem because it will increase the moisture level in the area, making it more suitable for fungus gnats. Plant pots with more drainage holes
- Ventilate your home. Good ventilation will help to keep moisture levels down, making your home less attractive to these gnats. Running a fan where you keep your houseplants is an excellent idea because it will help keep the air moving and less humid. As a result, your plants will be a much less attractive breeding ground for adult fungus gnats.
- Set up gnat traps. There are many different traps available that can effectively control fungus gnat populations. Even if you don’t see fungus gnats around your plants, adding a few gnat traps and flytraps is never a bad idea. If a few gnats do get inside, they will be much less likely to lay their eggs and cause a problem for your plants.
- Remove dead leaves and trimmings. Gnats are attracted to decaying plant matter, so removing dead leaves or trimmings from your plants is essential. This will also help to prevent the spread of diseases.
- Check the seals on your windows and doors. Fungus gnats can enter your home through the tiniest cracks, so it’s vital to ensure your windows and doors are properly sealed.
Keep your plants healthy and free of fungus gnats by watering them deeply but less often, using pots with good drainage, ventilating your home, and setting up sticky fly traps. Remove dead leaves and plant matter. Try hydrogen peroxide spray, neem oil, or beneficial nematodes.
Fungus gnats can be a problem for indoor gardeners, but there are ways to get rid of them! Try methods until you find one that works for you.