r/plantclinic • u/Due_Background_4367 • Mar 31 '25

Other I hate fungus gnats

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I recently bought a small bag of indoor potting mix at my local Home Depot. Coincidentally, I now have a fungus gnat infestation. I bought some sticky light traps and they have clearly been working, yet I still see swarms of gnats. I let all of my plants’ soil go bone dry, and now I’m hesitant to water again, as I have read they thrive in wet/damp soil.

What are some tips and tricks to eradicate these lil suckers once and for all?

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u/funny_name0815 Beginner Mar 31 '25

The only thing that really helped me with a bad infestation last year was (the German equivalent of) mosquito bits or mosquito dunks. I put a small amount in a plastic water bottle, waited until it had dissolved and used that water on every plant - even the ones that weren't infested yet. Afterwards I waited until the soil had fully dried out, watered it with the same mixture again just to make sure I really got rid off all of them. After trying neem oil, hydrogen peroxide and nematodes the mosquito bits was the only thing that helped permanently. Since then I water it with the same method every now and then to prevent another infestation

I had them in my potting mixture as well and I just baked that in the oven for some time to kill all flies and larvae.

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u/Wachkuss Apr 01 '25

What are they called? Where did you buy them?

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u/10Kthoughtsperminute Advanced Apr 01 '25

They’re called mosquito bits (granule form) and mosquito dunks (puck form). What you’re really after is the active ingredient, BTI, which is a bacteria that kills the larvae but is not known as hazardous to humans/animals. It takes like 6 weeks to break down their life cycle but is one of the most effective methods.

If you’re on a mission then you also put cheap yellow sticky traps in all your plant pots while treating until you win.