I have plants in every room of the house and plenty outdoors too. My collection ranges from thumb-size succulents to a dracaena taller than I am. I’m on and off my two balconies a lot to water and fuss over them. So the first few times I swatted a little fly getting up in my face, I assumed one had followed me back inside.
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The calathea started to struggle right away. I fretted over it, brought in a humidifier, moved the plant closer to and then farther from the window. Then the ‘Marble Queen’ pothos hanging in the window started struggling. The philodendron ‘Brasil’ began to droop. I took them down to get a look at the soil and was met with a face full of fungus gnats.
A lot of us became plant parents in quarantine. My collection expanded from a handful of cute little cactuses picked up on a whim at Trader Joe’s to a sweeping collection of more than three dozen posed in corners and on countertops in every room of my house. But as parents of all kinds know, even the cutest little additions to the family come with potentially unpleasant corollaries. Advertisement
Fungus gnats are one of the most common plant pest problems, and one of the most frustrating (and potentially expensive) to resolve. Google searches for “fungus gnats” and related insect elimination queries have ticked up since the start of 2020, as the people projecting pandemic stress onto their plants have found themselves in the same position I’m in.
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I have read just about every article on the internet about eradicating fungus gnat infestations. I have ordered 48-packs of yellow sticky traps from Amazon — three times. I have done toxic soaks and let poison pellets bloom in water overnight. I have top-dressed. I have bottom-watered. (For those of you who haven’t gone off the gnat-inspired deep end, top dressing is covering the soil with something that physically block bugs from accessing it. It’s also done for aesthetic reasons. And bottom-watering is when you let your plant soak up water through its drainage hole instead of pouring it over the top, which keeps that soil at the top from getting damp and attracting critters.) I have gone as long as possible without watering my plants before I start to feel dehydrated on their behalf. I have repotted. I have purchased strange devices, like the Katchy, a robotic insect vacuum that lures its victims with UV light and sucks them to their doom with a fan.
I’ve even done the unthinkable: I’ve had to toss some of my beloved plants. Some wilted and died as the gnat larvae chewed up their roots. Others were so profoundly infected that even multiple attempts at solving the problem failed, and I was forced to make a horticultural Sophie’s choice to save the rest. Advertisement
At The Times, we have an internal Slack channel for plant lovers where I have posted about my plight. Here’s what I have spent trying to combat the problem:
— Three 48-packs of sticky traps: $44 — Landscaping sand: $15 — Beneficial nematodes: $60 — Steel wool: $10 — Neem oil spray: $11 — Katchy: $40 — Bag of cedar shavings: $10 — Three Venus flytraps and specialty potting mix: $66 — Mosquito bits: $19 — Hydrogen peroxide: $5 — Bonide Systemic Houseplant Insect Control granules: $22
Total: $302. More than 10 times what the original calathea cost me. All of these items promised to ward off, murder, smother or otherwise expunge my pest problem. Only a handful succeeded.
Even worse? The gnats came for the dwarf Meyer lemon tree and the burro’s tail on the balcony. They got into my big dracaena, my fiddle-leaf fig, my bird of paradise. They unleashed their foul spawn on my pride and joy: my two big monstera plants. I’m so paranoid that I’ve caught myself aggressively swatting specks of dust out of the air. At this point, I am legitimately concerned that I have somehow bred a mutant strain that is immune to every treatment out there. Advertisement
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Before we get into warfare, a brief overview of the enemy: They are related to mosquitos but don’t bite people. They look like fruit flies but lay their eggs on damp soil, not past-ripe produce. They don’t carry any diseases dangerous to humans. The adults aren’t really dangerous to plants either. They are slow, clumsy fliers — rather satisfyingly easy to swat. Their larvae are the root eaters. And even those won’t be able to do much damage to most of your plants unless you’re profoundly afflicted. They have a roughly three-week lifespan, which is why it sometimes feels like you’ve finally, truly gotten rid of them, only for the cycle to begin anew.
So mostly, they’re annoying. As they search for a wet patch of dirt, you’ll often find them buzzing around your face, evaluating your moist holes for real estate potential. Or they’re in your water glass or crawling around your bathroom sink. They’re obnoxiously fertile, and the problem can escalate from nuisance to all-encompassing swarm in shockingly little time.
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Eradicate your fungus gnat infestation for good with the following method: Put up a bunch of sticky traps, top-dress the soil with sand and do nematode soaks every 10 to 14 days until the problem is resolved. Also, stop overwatering your plants and eliminate any unnecessary sources of moisture. That’s it.
The thing about fungus gnats is that you have to stop them at every stage of the life cycle to eradicate them. If you kill only the adults flying around by trapping them, some will get the chance to lay another round of eggs in the soil, and the cycle begins anew.
The yellow sticky traps “work” in that they capture a disgusting amount of twitching flying insects. But they capture only adult fungus gnats and not necessarily before the bugs have had a chance to lay eggs. If you catch the problem early, a strong line of sticky trap defenses might be enough to stop it in its tracks, but I was too far gone for this to be sufficient.
“Top-dressing” is when you cover the soil with another medium to make it inaccessible to insects. I initially tried steel wool after seeing a post about it on Reddit. That was not successful; they still had plenty of room to fly around. I tried again with a robust bag of landscaping sand from a big-box hardware store. The sand gives enough coverage to prevent the adults from laying more eggs and traps the larvae in the soil, stopping them from wriggling to freedom. You can still water your plants at the top if you want to. It will just go through the sand. You need only about a quarter inch to a half inch of sand on top of the soil to do the trick. Get it around the base of the plant and all the way to the edges of the pot: Fungus gnats are wily and will gladly take advantage of any opening you give them. Advertisement
Adult fungus gnats are annoying but largely harmless. The larvae are the ones sucking the life out of your precious plants by chomping on the roots. Enter nematodes, or microscopic roundworms. It might sound counterintuitive to fight your insect problem by bringing in more of them, but these are the beneficial kind. Nematodes will seek and destroy the larvae, which prevents the next generation of adults from forming. (Don’t Google how that process works unless you’re prepared to sleep poorly tonight. OK, fine, if you must.) Because you probably have gnats at various stages in the life cycle, you have to do the nematode soaks a few times to get them all.
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I bought some nematode “pot poppers” online; I put the little sachets into my pots and they didn’t seem to do much. After strenuous urging from Jones, the beekeeper, I tried again. I got the kind that looks like a bag of finely grated Parmesan, which you put in water and then pour over your plants. It made a noticeable dent in the gnat population after just one application.
Every person I spoke to for this article told me I was overwatering my plants. I swear I am not overwatering my plants. I don’t water on an app’s schedule like a nervous first-time plant mom. I stick my finger in the soil and check further down with a moisture meter.
But when I got the bug-trafficking calathea, the soil was very damp. Brown, the entomologist, said it almost definitely came from an infested greenhouse. Greenhouses are humid and full of plants that get watered frequently, he said, and thus are a somewhat intractable scene of fungus gnat issues. Similarly, anywhere in your house that has moisture is keeping the gnats interested.
Jones asked me a question that made my blood run cold: Did I have water sitting in my plants’ drainage trays? Guilty. Sure, I was letting the topsoil thoroughly dry out, but I was practically offering a buffet at the drainage holes.
So, to recap: Put a few cheerful little literal death traps around your plants in the form of sticky traps. Cover up the soil with sand. Keep a bag of microscopic roundworms in your fridge. Wipe down your drainage trays and do whatever you can to minimize moisture. Advertisement
Aaron’s beard plant, also known as string of pearls, is a unique and beautiful succulent that can liven up any indoor space. However, like many houseplants, it is prone to gnats infestations. These tiny flying insects can be bothersome and may even damage the plant if not addressed. In this article, we’ll discuss how to identify and eliminate gnats in your aaron’s beard plant.
Identifying Gnat Infestations
Before treating gnats, you first need to confirm they are present. Signs of gnats include:
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Flying insects hovering over the soil: If you notice small flies near the soil, you likely have gnats.
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Tiny worm-like larvae in the soil Gnats lay eggs in damp soil The hatched larvae are small, white worms that feed on organic matter.
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Wilting or yellowing leaves: Larvae damage roots leading to nutrient deficiencies.
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Visible root damage: Severe infestations may visibly decay roots.
If you spot any of these signs, take prompt action to control the infestation before it spreads further.
Methods to Eliminate Gnats
Allow Soil to Dry Out
Gnats need moisture to thrive Allow the top few inches of soil to dry out between waterings Improve drainage by using soil amendments like perlite, Letting the soil dry out makes conditions less hospitable to gnats,
Remove Infested Soil
If the soil is heavily infested remove the top 2-3 inches of soil which likely contains gnat eggs and larvae. Replace with fresh sterile potting mix. This eliminates larvae and prevents reinfestation.
Use Sticky Traps
Sticky yellow traps placed near the plant attract and capture adult gnats, reducing the population. Change the traps regularly to maintain effectiveness.
Apply Neem Oil
Neem oil is an organic insecticide that can kill fungus gnats. It disrupts their life cycle and controls larvae and adults. Follow label dilutions and precautions when applying.
Use Mosquito Bits
Mosquito bits contain bacteria that kill gnat larvae but are safe for plants. Simply sprinkle them over the soil and water in. The bits will gradually release bacteria to eliminate larvae.
Apply Diatomaceous Earth
Diatomaceous earth (DE) is a powder that kills insects through abrasion and dehydration. Gently apply food-grade DE on dry soil wearing a mask. It will reduce gnats through contact.
Use Hydrogen Peroxide
A 3% hydrogen peroxide solution can be used to drench soil infested with larvae. As it breaks down, it releases oxygen into the soil. Repeat applications may be required.
Deploy Beneficial Nematodes
Some nematodes parasitize and kill gnat larvae. When applied to soil, they seek out and infect larvae, eventually reducing populations. Follow label instructions for best results.
Adjust Watering Habits
Excess moisture promotes fungal growth for larvae to feed on. Allow more time between waterings and inspect soil first to prevent overwatering. Improving drainage also helps keep soil drier.
Improve Soil Aeration
Gnats dislike airy soil that drains readily. Incorporate amendments like perlite, orchid bark or horticultural charcoal to improve aeration and drainage.
Apply Cinnamon Powder
Cinnamon is said to have anti-fungal properties that may deter fungi growth and disrupt larval development. Lightly sprinkle on dry soil. Results vary, but it’s a natural option to try.
Use Yellow Sticky Strips
Strips coated with sticky glue and hung near plants can help reduce adult gnats which are attracted to the yellow color. Be sure to replace strips regularly as they fill up.
Prevention Moving Forward
Once you’ve eliminated current gnats, implement preventive measures to avoid future infestations:
- Allow soil to dry out between waterings.
- Improve drainage and aeration.
- Avoid over-fertilization which can accumulate salts.
- Prune off dead leaves and debris.
- Keep the area clean and free of rotting produce.
- Use yellow sticky traps continuously to catch stray gnats.
Catching gnat problems early and adjusting care routines makes treatment much easier. With the right techniques, you can keep your aaron’s beard and other houseplants pest-free.
Here’s what doesn’t work
I tried a lot of things I read online. Here are some suggestions I tried that yielded unsatisfactory results.
Neem oil spray can be effective against a variety of plant-destroying insects. But unless you really, really soak the top 3 inches of the soil, it won’t kill all the fungus gnat larvae. At best, it seems to weigh down the flying adults enough that they’re easier to swat.
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The Venus flytraps were simply not up to the task. At one point there was a fungus gnat corpse in every single one of their sticky little mouths. They’re so overworked and exhausted that they can’t even close their tiny teeth anymore. The dead bugs have to wait their turn to be consumed. At the height of the issue, I estimate that I would have needed a carnivorous plant on par with Audrey II from “Little Shop of Horrors” to adequately address this. I did get to watch the flytraps bloom, though.
Jones, the beekeeper, recommended I try cinnamon or cedar shavings on the soil. She said the gnats don’t like those scents, so they act as a deterrent. It did not seem that many were deterred.
The Katchy is a device with a little light that attracts gnats and mosquitoes and a window vortex that sucks them down onto a big sticker. It has captured a satisfying number of victims but does not fully address the problem.
Mosquito bits are little pellets that contain a bacteria that’s toxic to fungus gnat and mosquito larvae. You scatter them on top of your soil or let them sit in your full watering can for a few hours or overnight to marinate. I tried both with limited results. Advertisement
“Bottom-watering” is when you put your parched plant in a bucket of water and let it soak up what it needs through the drainage hole. (It’s very fun. “Like a magic trick,” said Adams.) This keeps the top of your soil dry and therefore gnat-egg-proof. But if the water leaks back out into the tray, or if the hole is accessible to the gnats, you could just end up with the problem at the bottom of your plant instead of the top.
You can also repot your plants in fresh, sterile soil. But unless you repot all of your plants at once, and very thoroughly clean the inside of the containers and get every speck of dirt off the fragile roots, your efforts may be futile.
How to Get Rid of Fungus Gnats | DIY Remedy | creative explained
FAQ
What is the fastest way to get rid of gnats in plants?
How do I get rid of gnats in my Calathea plant?
What can I spray on indoor plants to kill gnats?
How do you get rid of cedar gnats?
How do you get rid of gnats on plants?
Here’s how to use it: Step 1: Dilute the hydrogen peroxide with water at a ratio of 3 teaspoons of hydrogen peroxide to 1 cup of water. Step 2: Add the mixture to a spray bottle. Step 3: Spray your plant with the mixture twice a week until the gnat infestation clears up.
How to get rid of gnats in potting soil?
To get rid of gnats in potting soil, a solution of 3% hydrogen peroxide mixed with water can be effective. The hydrogen peroxide releases oxygen when it comes into contact with organic matter in the soil, suffocating and killing the gnats and their larvae.
Should I repot a plant with fungus gnats?
While repotting a plant with fungus gnats is not always necessary, it can be a useful step in controlling the infestation. Repotting the plant in fresh soil can help remove the gnats and their larvae from the soil and prevent them from laying eggs in the new soil.
What causes gnats in houseplants?
Root rot. In many cases of overwatering a plant, the roots will begin to rot and spread through the soil. Gnats come into play here because they love moist environments, so if you notice your plant has symptoms of root rot there is a good chance you may have fungus gnats.