Hey all,
I'm growing mushrooms for my first time!
I have no growing experience at all so I decided to just use a commercial kit, though it's against my usual DIY attitude.

I now have a little cardboard box containing a bag with my substrate, a layer of soil, and a lid. Basically a planter box. I'm waiting for pinning at the moment.

I was misting the topsoil today and I saw it... a fungus gnat happily floating around in there. I realize I kept a potted plant nearby and they certainly spread from there—doh. So now I've got the issue of eradicating these little rascals before they lay eggs.

I'm hoping for a solution that won't bother the mushrooms too much. Other sources suggest vinegar, soap, or drying out the soil, but I suspect the mushrooms would be none too happy about any of those. Ideas?

Yeah, gnats can ruin a grow and that is really disappointing.

You can try dumping a generous amount of diatomaceous earth on top of the soil of the potted plant. It's probably best to put some in the saucer (or pot cover, whatever) as well because the gnats will come out of the holes at the bottom of the pot too. As far as the grow goes, I can't say if this would work for your casing soil too but it would be worth checking to see if anyone else has tried it.

I've lost a few tubs to gnats. It made me switch to the 'sealed' sterilite gasket boxes and low loft polyfil stuffing to keep them out of the tubs. If it's completely colonized I would just move it to another container with poly stuffed holes. Vinegar or H202 will hurt the mycelium. If it was a kit the gnat eggs could have been in there the whole time. I hate kits. I've probably read 10k bad experiences on Shroomery about them.

Some apple cider vinegar with a spoon full of sugar and a couple drops dish soup in a cup is the best gnat trap ever made. Eradicated gnats in my home.

I don't figure they were in the soil by the time I applied it to my substrate, as I had the soil in the microwave for ten minutes after moisturizing it. If any eggs survived that, then hell, they probably deserve the mushrooms.

Anyway, thanks for the tips so far. I will try the trap and the d.e. and hope for the best.

I'm just concerned those tiny little blighters will get through the smallest of gaps given half a chance. That's how they got into one of my tubs once and ruined all the cakes. They will eat the myc and spread contamination. I really got my fingers crossed for you on this one.

I just got done with my first run of BRF to bulk shoebox. If you follow BODS easy as funk cheapest way to grow tek on shroomery you'll be good to go. Gnats cant get through the lid of a shoebox

Oh yeah they will. They climb right through normal tubs or "shoeboxes" (those have a 1/4" gap around the lid, mice can climb through). The only way to stop them would be with tape like micropore around the lid where it meets the tub but that will really dampen your FAE. Shoebox lids don't even slow them down. They are the sole reason I switched to the gasket tubs with the stuffing. That stuffing stops mold spores, gnats can't get through and the gaskets maintain a seal by use of clamps, it's gnat proof.

I found a gnat in my microwave a few days ago. Out of interest I tried cooking it to death. 3 three minute rounds later and the results were- Gnat = 1, Microwave = 0.

While this might not get rid of them entirely, I used these with great success with cannabis when there was a gnat takeover. Saved the grow entirely:

Yeah, so to my horror I discovered there were many, maaany more gnats in the depths of my casing soil. Their life cycle may be short, but I doubt that two dozen individuals could have arisen in the one day that I moved it into the sun room.

I believe the microwave is insufficient to kill gnat eggs, like Dirty T says. In the future I'll put my soil in the pressure pot or something...

Anywho. I bought diatomaceous earth and some pyrethrin insecticide. I dumped the killer powder all over and mixed it in to the soil with a gloved hand. I notice a lot less activity but it's only a few hours later. I'll post if the crop is successful.

Do gnats restrain themselves to the soil, or do they f*ck up the mycelium in the substrate too? I'm early in the growing cycle so I hope after I stop them from reproducing any further, my very large amount of mycelium will recover once the larvae had had their fill and grown up (and died before laying eggs).

Do what tatt says. I use those sticky traps in my plants too and they will disrupt the life cycle enough to eliminate gnat infestations.

Oh yeah SeeingIsBelieving, the gasket boxes are the absolute greatest for mush! Keeps the bugs out and gives excellent control over conditions.

Bismallah, it depends on the type of gnat whether or not they eat mycelium. I've dealt with both kinds. There is one kind that absolutely destroys mycelium. I had a few tubs without gaskets a while back, never again!

I think the pesticide + d.e. combo nuked them... I don't see any crawling around. I'm sure there are still grubs, but no gnats.

If somehow they persist I will make a sticky trap.