How to get rid of those pesky fungus gnats for good!

Ever wonder what those tiny “fruit flies” are that are flying around your houseplants? If you love Calathea, stromanthe, or prayer plants, you’re likely to see quite a few of them flying around. Any plant collector may tell you that swatting, squishing, or batting at these tiny pests comes with the territory. These are fungus gnats, and they may seem horrifying if you haven’t dealt with them before. Luckily, they are some of the least lethal houseplant pests around. But left untreated, they can still do some damage to your plant collection. Not to mention, they’re a nuisance! Here are some tips on how to get rid of fungus gnats.

What are fungus gnats?

Fungus gnats are tiny flying pests that may look like mosquitoes or fruit flies. They may be seen flying around your houseplant or crawling around in the soil. They love damp, rich or moist soil so they love to populate your moisture-loving houseplants. Their lifespan is roughly 7 days but in that time, they can lay hundreds of eggs in that moist soil. Their life cycle consists of egg, larva, pupae and then fully grown adult fungus gnat.

Tips for getting rid of fungus gnats:

1. Inspect new plants before bringing them home and isolate and observe plants you do bring home

Prevention is the best practice when it comes to fungus gnats! If you notice a plant is infested with flying fungus gnats in a greenhouse or plant store, sometimes the best thing you can do for your plant jungle is to either pass over that particular plant, or bring it home and immediately isolate it and treat it individually before they spread to the rest of your collection. Don’t forget, fungus gnats are fliers so you may want to keep your new plant in a separate room or location and monitor it for several weeks.

Here’s a full guide on what to do when you bring a houseplant home, if you’d like more tips!

2. Yellow sticky tape

The easiest way to get rid of those fungus gnats is also the most popular. Fungus gnats are drawn to the bright yellow coloured strips of this yellow sticky tape and will stick to them and therefore prevent them from laying more eggs. It may take a while and some patience to completely eradicate them, but it is a simple “set it and forget it” solution if you’re a busy plant parent.

3. Making the soil less desirable

Adding sand, gravel, or decorative stones to the top of your soil is another great option to get rid of fungus gnats. The adults won’t be able to settle into the moist soil to lay their eggs and continue their life cycle. They are particularly attracted to moist or wet soil, so this is another great reason to avoid overwatering your plants.

4. Mosquito Dunks

These are not the easiest to find in Canada, but many houseplant owners find incorporating mosquito bits or mosquito dunks into their watering routine to be a very effective way to prevent or eradicate fungus gnats by killing them off in the egg and larva stages. Eventually the adults will die off as well, and you will be rid of fungus gnats for good! Many people find this method especially effective when combined with the yellow sticky tape to kill both the adults, eggs and larva quickly.

5. Hydrogen Peroxide Soil Treatment

Hydrogen peroxide soil treatments are another way to get rid of your houseplant pests, including fungus gnats, but proceed carefully. Using a diluted mixture of hydrogen peroxide will effectively kill any eggs or larva in the soil and prevent pests from reaching adulthood. This is typically a last resort for heavily infested plants and should not be done on a regular basis as it also kills any helpful components in your soil. But sometimes desperate times call for desperate measures!
A full blog on this process is coming soon, but in the meantime, I recommend this video by Harli G, for a full deep dive on how hydrogen peroxide can help your houseplants.

In Conclusion…

Getting rid of fungus gnats can be a bit of an ongoing process as they tend to emerge and re-emerge seasonally. It’s important to find a method that works best for your personal collection and your own plant care routine. If you want to prevent houseplant pests in the first place, as best as possible, check out this article!

I’d love to hear your experiences with fungus gnats. Maybe there is a particular combination of measures that do the trick!

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