Gnasty gnats: the struggle is real

[Atom#28]

I am using my grow tent as a kind of hospital for my saddest plants. Why? I guess I don’t know any better. But it seems to be working: I have a couple of collected Douglas firs, a collected elm, a struggling larch (as an experiment), and a number of jades and p. Afra and ficus, too. They’ve all been happy with the humidity, warmth, and consistency thus far. However, so have these goddamned motherfucking shitass bastard demon flies. The yellow sticky traps are catching lots and lots, but is there a better way? Is there a treatment to kill their earlier life cycle stages? I worry their larvae are wreaking havoc underground.

 

[leatherback]

Letting the soil dry out more?
Insecticidal drench?

Guess you have created a perfect insect breeding ground there.

 

[Shibui]

Warm indoors with high humidity is ideal breeding for fungus gnats. They love wet organic soil.
Letting the soil dry out is one way to minimize them.
Peroxide is a plant and human safe treatment that kills fungus gnats quickly and efficiently. Mix 1 part 3% hydrogen peroxide (supermarket or pharmacy) with 4 parts water then drench the soil with the mix. It will fizz and bubble up like a volcano but I have not had the soil overflow the pot (yet) so do that outdoors just in case. It all settles down in place after a few minutes and the fungus gnat larvae will be dead and gone.
I'd try a couple of treatments a few weeks apart in case some of those adults lay more eggs after the peroxide dissipates.

Fungus gnats are not just a nuisance flying round but the larvae eat roots as well as rotting organic matter so won't be doing the trees any good.

 

[RJG2]

This is what I've used in the past, definitely worked for me. Had a bunch at the beginning of winter, and haven't seen them since.

I only needed them in my one pot that is in organic media (hasn't been reported since arriving from Wigert's).



Contains a bacterium that kills the larva.

 

[sorce]

There is an easier fix to the problem.

How many bandaids can you stack on one wound?

Sorce

 

[Atom#28]

Sad. I guess my “hospital” is more like a poorly-run hospice. My plan is to increase ventilation and decrease humidity, and observe. Thanks, guys

 

[LittleDingus]

I used to get terrible infestations in the house in the winter. I used those same yellow tack papers for a while. What helped most, however, was inorganic soil.

The live off rotting material: hence "fungus" gnats. They lay their eggs in same. They are most susceptible to chemical treatments when eggs or larva. You need to treat every couple of days to kill any new eggs or larva otherwise the adults just "skip over" your treatments and lay more eggs when after the treatment.

Inorganic soil gives them no place to live. If you have something in organic soil you cannot repot to inorganic soil, run out to NAPA and ask for a bag of oil dry: NAPA 8822. Or run to Home Depot and get some coarse sand. Either are dense enough that a 1/2" layer over the organic soil prevents the adults from finding a place to lay eggs and prevents any eggs/larva from escaping.

Since I started top dressing my organic soils this way, I've not had gnat issues

 

[Grovic]

The water and hydrogen peroxide solution works like a charm, it's easy and you don't have to worry about chemicals in your home. You'll get rid of them in no time, you can keep the sticky traps for a couple weeks to catch the ones that are not in the soil.

 

[just.wing.it]

Set fire to the whole thing.....just to be safe.

 

[penumbra]

First and foremost, take a deep breath.

 

[canoeguide]

The mosquito bits shown above are inexpensive and have 100% solved every problem I've ever seen with fungus gnats.

 

[HorseloverFat]

Mosquito bits NOW to control the infestation... then never let it get like that again.... non(or less)-organic soil indoors...

Fans, fans, FANS!! (Make sure some (or one) of them are aiming at the BOTTOMS of the pots)

Aim for 55 humidity, indoors... anything higher, in an attempt to make it “Feel like a greenhouse” will most likely be more detrimental than harmful then beneficial... unless you are running a professional, self-contained room.

Also.. DE powder shreds those little bastards.. so that COULD fall under my “non-organic soil indoors” recommendation.