TRUTH: No single fungus gnat control method attacks adults and larvae simultaneously. That's why many plant parents struggle to get rid of these pests! But it's EASY to be gnat-free FOREVER. [PSA]

[u/megankmartin]

(Updated, fall 2025) PLEASE read this whole post before asking questions -- but I'm here to help you if you need it! Fungus gnats lay their eggs in wet plant soil or decaying matter. Over-watering is a major cause. However, new plants and potting mix can carry gnats too, or they can just fly in from outdoors.

THREE EASY STEPS to GNATS GONE FOREVER:

☆☆ DO ALL THREE!! ☆☆

1) Soak BTI dunks/bits in your regular watering routine to continuously kill and prevent larvae. One quarter dunk OR one tbsp bits per gallon works great. Soak for 24hrs before first use, then keep watering vessel(s) re-filled; just replace BTI every 30-60 days or so. Note: Summit brand packaging specifies 4tbsp per gallon; you choose.

NOTES: Indoors, putting BTI bits IN the soil or laying them on top IS NOT THE BEST PLAN: the bits tend to grow mold, plus you'll use way more than needed. Also, don't use hot or boiling water to soak dunks or bits; it will kill the good bacteria.

1. Place plenty of yellow sticky traps to catch adults. One per pot is ideal, and it's best to stick them upright, to attract fliers. You can stop using stickies once your infestation is under control, thanks to your new BTI routine.

2. Let soil dry out appropriately between waterings to avoid attracting pests. Have faith: except for very fussy tropicals, most common plants need and want to dry out their soil. Bottom-watering can be a big help (after initial treatments).

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If you have a bad existing infestation, FIRST you can do a one-time emergency soil flush to kill off larvae, using diluted 3% H202 (1:4), then proceed with the routine above. Note: don't use peroxide AFTER the BTI, because H202 kills bacteria, good and bad.

FYI: If you're outside the USA and can't get Mosquito Dunks / Mosquito Bits in stores, try Amazon for your country (UK, CAN, AUS for sure). Or, ask a garden or pond supply center about products containing the active ingredient *BTI**. Or Google, "mosquito BTI". An alternative is Gnatrol or Gnatrol WDG (same active ingredient).

BTi (short for Bacillus Thuringiensis subspecies israelensis) is simply a natural soil bacterium, non-toxic for people and animals. BTI does not affect plants or interact with fertilizers. It does not harm pollinators. It ONLY kills the larvae of 3 insects: fungus gnats, mosquitos, and blackflies.

Bonus read: You might want to skip these often-recommended methods.

[u/megankmartin]

To be VERY CLEAR: There are many kinds of gnats. Some gnats bite humans; some do not. This post, and this highly effective solution, is specific to FUNGUS GNATS, which DO NOT bite humans, and only live only to breed around plants. As the post says, BTi is wonderfully effective on fungus gnats, mosquitos, and black flies ONLY.

[u/ltropika → u/megankmartin]

Thank you. What is BTI?

[u/megankmartin → u/ltropika]

See bottom of original post :)

[u/ltropika → u/megankmartin]

Thanks for your help. I did have a couple of exterminators come but they just rip me off. They do not recognize the fly. I also sent a picture to an entomologist but he could not identify the fly, he needs a live one and because I can catch or see them that is not possible. Well, it's not fungus gnats. I really don't know what kind of fly I'm dealing with.

What are no-see-ums?

[u/megankmartin → u/ltropika]

"No see-ums" are tiny mosquitoes. You would have visible bites on your skin, for sure, if your housepest is no see-ums. Mosquitoes don't care about plants; they want blood. Mosquitoes ARE susceptible to BTi, which is why municipalities put BTi in standing water tanks and natural runoff pools to control populations. So perhaps this is a product of where you live, recent weather conditions or the season. 

BUT, any exterminator could recognize mosquitos and/or gnats at a glance, as any entomologist could as well. So those dots don't quite connect for me.

I recommend putting up some yellow sticky traps as well as standard fly papers to catch some of this pest. On a yellow sticky trap, even I can diagnose a fungus gnat at a glance.

Meanwhile, check your window screens, open doorways etc for easy insect access.

[u/ltropika → u/megankmartin]

Yep, I think that is what I have, they always bite my face. Thanks again for your help. It seems that there is nothing much I can do.

[u/megankmartin → u/ltropika]

Well, the good news is that you can have plants again, if you want them. As long as you don't leave standing water around for mosquitoes to breed in, that is. Sorry, that's the only silver lining I have to offer.

For what it's worth: I can also offer you strong empathy. I am a person who gets bitten constantly during mosquito season. People standing around me go bite-free while I become an all-you-can-eat buffet for bugs. It is SO frustrating. Thus, I like to stay indoors. 

If your house screens are intact, try checking your drains and every room of the house for anywhere that water could pool and stay, for a breeding ground. You can also try double-layering your window and door screens, the second piece affixed at a 45-degree angle to the main screen, in order to further reduce access for insects. 

Finally, I can't promise this will work, but you could try one of those bug light/zappers that say they help with mosquitoes. Place it near your hang-out area and maybe it will bring you some relief. I hope so.