Fun with Fungus Gnats!

Ok, there’s no fun in a fungus gnat infestation. And unfortunately, it’s a common problem. It's one we are asked about all the time. There are a few reasons you might have fungus gnats: an overwatered plant (gnat larvae LOVE damp soil), insufficient drainage, and purchasing a plant/soil where fungus gnat larvae are living. 

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It can take a few weeks to months to break the cycle: The larvae hatch, fungus gnats fly, harass you, and lay more eggs in other moist plants. 

 Let’s start with the adults (flying around your kitchen and bathroom, where water is): Sticky traps, and “DIY” traps like apple cider vinegar and a little dish soap in a shallow dish) That attracts and drowns the gnats can work. But here’s our favorite, discovered by chance after a nasty infestation in an apartment a few years ago:

1. Grab a cup of coffee. Add a liberal amount of flavored Cremora/sweet creamer. (International Delight Caramel Macchiato and Hazelnut are personal favorites. We’re sure generic flavored liquid creamers work just as well.) Attached are photos. One is of fungus gnats from a customer who sent this after we suggested. The other is from my house, where we constantly leave the doors open for the dog. You can see who won in the “housefly vs. sweetened coffee battle.” 

2. Drink most of the coffee, leaving about 3 ounces in the cup.

3. Leave cup out overnight near a light. 

4. Wake up, check cup, see 3 - 50 drowned gnats, depending on the level of infestation. Express disgust and throw it down the drain, running water after.

Note: This treatment is intended for adults only; however, without adults, there should be no new eggs. To prevent adults, you need to get rid of the eggs: 

1. Start with STOP OVERWATERING. It can be part of the cycle. Overwatering leads to root rot and mold, and larvae feed on the rotting roots. Larvae can also kill the roots. Eggs are deposited just under the top of the soil. Scraping the top layer of soil can also work.

2. Hydrogen Peroxide: Mixing one part 3% hydrogen peroxide with four parts water creates a solution that kills fungus gnat larvae when applied to the soil. Fun fact: The mixture will fizz as it reacts with the larvae. Let soil should dry out afterward to prevent re-infestation. (This also works when bringing in plants for the winter.)

3. Bottom water: Will prevent super soggy soil at top.

4. Make sure you have adequate drainage soil soil can dry.

5. Use BTI (Bacillus thuringiensis israelensis) (“Mosquito Bits”) to control fungus gnat larvae. It's a naturally occurring bacterium that produces toxins that specifically target and kill the larvae of fungus gnats.

6. Beneficial Nematodes, predatory mites (this is more involved… look them up. It’s essentially “microscopic worms and mites that eat fungus larvae.”) 

 

If you tried this method and it works, shoot us a photo and let us know.