There has been a huge increase in fungus gnat problems in recent years, leaving many plant owners scratching their heads. Where are these bugs coming from, and how do we get rid of them? We put together this guide to help houseplant collectors understand why fungus gnats appear and how you can eliminate them for good.
What Causes Fungus Gnats in Houseplants?
Fungus gnats earned their name because they eat fungal growth. What causes fungal growth in houseplants? Overwatering!
We’re seeing way more gnats these days because people are spending more time at home. When you’re at home most of the time, the temptation to water your plants is high, and people are overdoing it! Too much water will hurt your plants far more than not enough water. If you’re seeing gnats buzzing around your plants, you have to kick that habit of overwatering, and quick!
How to Get Rid of Fungus Gnats in Plants
The tricky thing about gnats is that you aren’t just dealing with the mature flies—they lay their eggs in the soil, which eventually hatch into larvae. The larvae mature, lay more eggs, and the vicious cycle continues. The mature gnats don’t do much damage—they’re mostly just annoying—but the larvae pose a bigger problem: they chomp on your plants’ roots. If you neglect to deal with the problem, your plants could sustain significant damage.
To get rid of all the gnats buzzing around your house, you will have to target both the mature insects and their larvae. They mature and reproduce quickly, so a combined approach using several pest control methods will work best.
Let the Soil Dry Out
Since overwatering is the cause of fungal growth that gnats feed on, the first thing you have to do is stop watering and let the soil dry out. Don’t worry about your plant getting thirsty—it’s much easier for plants to bounce back from underwatering than overwatering. Once the soil has remained completely dry for a few days, resume watering, but don’t go overboard! Containers with drainage holes can help stop excess moisture from pooling at the bottom.
Traps are a great quick fix for getting rid of buzzing gnats, especially if you have company coming over. Just stick a few sticky traps in your plants’ pots, and the bugs will get stuck. Toss them in the trash, and you’re good to go.
You can make a great homemade spray for fungus gnats with just water with a few drops of neem oil—a potent essential oil that kills mature flies and larvae, no chemicals required! Shake it up in a spray bottle, coat the leaves and soak the soil. Repeat the process every few days until no flies remain.
Pyrethrin is an all-natural insecticide that comes from the chrysanthemum flower. Spray it all over the leaves and soil to kill mature insects and larvae. Make sure you don’t use pyrethrin on outdoor plants—it kills butterflies and bees, which is a big no-no!
Mix peroxide and water at a 1:4 ratio; pour this into the soil, and it will kill larvae while also helping to clear out fungus and harmful bacteria. After a few weeks, add some compost or fish emulsion into the soil to help replenish the healthy bacteria.
Replace the Soil and Clean the Pot
In severe cases, your best bet may be to replace the soil entirely with a fresh batch and thoroughly sanitize the container. Be careful not to jumble the roots around too much. Your plant is probably already stressed out, so proceed with caution!
If you’re dealing with fungus gnats in Iowa, Ted Lare Garden Center has everything you need to send those bugs packing. Visit us soon to stock up on all the necessary supplies!