Fungus gnat experiment #569

FKH said:

Having read through all 8 pages of this thread, I'm still considering starting my grow.

As a few have mentioned, the larvae are present in the soil when we buy the bags. They eat the organic material. Once moisture is added, they go nuts.
An adult female fungus gnat can lay up to 300 eggs which hatch in 4-5 days. Their whole life cycle last about 25 days.

I ended up with an infestation that was so bad, I trashed my entire setup. Tent, light, bags, everything.

That's why I joined RIU, to try to prevent this from happening again. But it's not looking too good from what you guys have been posting here.


How common are fungus gnat infestations with hydro set ups? Maybe this is not the best thread to ask that.
Considering a Bubble Bros. setup from HTG. Yeah, I know, hydro has it's own problems.. Maybe NFT?

I dread spending $500.00-$600.00 on a set up and having to trash it all, again, because of these bastards.

Fungus Gnat Life Cycle | Orkin

Each part of the four-stage Fungus gnat life cycle takes only a handful of days to complete. The four stages include egg, larva, pupa, and adult. These pests do the majority of their damage in the larval form.

www.orkin.com

Wishing y'all the best with your situations.

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I run flood and flood and drain with hydroton and haven't seen a gnat in that tent since. Using an Aircube system from Growace and my only complaint is too much growth in it...I have to deliberately stunt plants to keep them from going wild.

Yea after a while of this I dont see gnats as stupid critters they very well may be farmers like leaf miner ants thats a good point.

Drop That Sound said:

Not really as common, IME. The few times I had fungus gnat problems in DWC is because I had other nearby plants potted up in infested medium.

You're more likely to attract or introduce gnats if you use anything organic when transplanting seedlings or clones to the netpots. Especially when using rapid rooter or jiffy plugs or anything like that.

I have a hunch that they actually bring in root pathogens on purpose. Or produce some kind of enzymes on their own, to help make the roots rot out so the larvea can feed!

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Hm... Wow, you make some really good points. Things I had not considered. Thanks.

I've always started seeds using using Jiffy or similar type plugs. Time to make some changes.

driver77 said:

I run flood and flood and drain with hydroton and haven't seen a gnat in that tent since. Using an Aircube system from Growace and my only complaint is too much growth in it...I have to deliberately stunt plants to keep them from going wild.

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That Aircube system! Really nice. Damn.... I may have found my next system.

Thanks!

I've a bag of used coco it's been sitting sealed up for months, when I went to it I looked in and couldn't see any gnats, would you agree if there were gnats breeding I'd see something in the bag?

About 2/3 wks ago I had a good look and also put a sticky trap in the bag and there's nothing at all on it today, tbh idk how that can be or what to make of it.

They had a inflated bag of space to fly around in they're big bags?

I've been using microbe lift bcm for years along with predatory mites and nemetodes. UvB +UvA help a great deal as well. Gnats are inevitable when substrate has fungi in it, but mulching helps. At some point the population on BT-i will dominate but you've got to catch the adult fliers, otherwise 1 female can lay 400 eggs every 10 days and without catching them, they'll just keep breeding and laying eggs for the duration of their lifecycle. You really must have an IPM program that addresses both larva and adult. I still see the occasional adult here and there but nothing ever takes hold. Yellow sticky traps, beneficial predatory macros, micros and UV enrichment WILL fix the problem.

It's also worth saying, don't buy compost or any soil conditioner and trust it's clean of pests. If you live in a state that has a winter season, let that shit freeze out in the garage for the winter and use it the following spring. Dramatic difference. I've been making my own compost for many years now and I have completely stopped using it before it's had a chance to freeze. Use only finished compost that's properly aged.

Star Dog said:

would you agree if there were gnats breeding I'd see something in the bag?

They had a inflated bag of space to fly around in they're big bags?

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To be safe, try a handful of soil from the bag and get it nice and wet. Isolate it and watch to see if you get fliers. It seems when moisture is added that the eggs start hatching.

Star Dog said:

I've a bag of used coco it's been sitting sealed up for months, when I went to it I looked in and couldn't see any gnats, would you agree if there were gnats breeding I'd see something in the bag?

About 2/3 wks ago I had a good look and also put a sticky trap in the bag and there's nothing at all on it today, tbh idk how that can be or what to make of it.

They had a inflated bag of space to fly around in they're big bags?

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Thats my experience no gnats in plastic tub with lid for 5 months sitting. Idk if when they say hatch when time is right if it includes roots, the gnats sensing the mycelium etc then hatch to eat idk. Maybe they only implied its only dependant on rh and temp. So far I got nothing almost a month later.

If youre wrapping pots up and seeing gnats and werent wrapping from the start id say thats why. I literally have to but I think the numbers arent as bad this run with the new changes of fabric pot dryback with low rh and high airflow.

Maybe one earlier was right they dont breed as bad if they dont have as much surface area and freedom.

skink#1 said:

I did not see a single gnat in my tent tonight. There's not much in there at all really.
I saw one flying around outside and a couple of new hatched crawlers I sprayed with Zymes. I love that stuff for knocking down flyers and anything on soil surface.
I use BTi every watering. At first I wondered if it was going bad. I thought maybe the gnats are becoming resistant.Then I realized that the soil is filtering the bacteria and the larvae are burrowing deep which they can do. So thorough watering as much as possible. Being vigilant and spraying pot tops with Zymes is important. Stickys. And if I had the dough I'd use nematodes too. I've used nematodes before and wiped out the gnats. And I've wiped them out as well 100% with Gnatnix which is illegal now and something I would not use because it kills worms and in a horrible fashion.
I can say I have the gnats under control. But somehow the tenacious fuckers survive.

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is the zymes you mentioned from dr zymes? ive been using a combo of neem oil, microbe lift-bmc, cannatrol, and diatomaceous earth to keep the gnats at bay but they always come back.

medidedicated said:

Thats my experience no gnats in plastic tub with lid for 5 months sitting. Idk if when they say hatch when time is right if it includes roots, the gnats sensing the mycelium etc then hatch to eat idk. Maybe they only implied its only dependant on rh and temp.

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Yes that seems logical bud, how could they get from one year to another without some kind of long term strategy for the long winters outside?

@FKH hey bud welcome to Riu.
Jfc the coco was left wet with roots intact.

Fwiw folk's I've still not seen any gnats since it's now getting on for 3 weeks.

How can fungus gnats survive winter if their lifecycle is 1 month?
The readily available info isn't very extensive its only half accurate and very basic.

From what I last checked they can last too long for winter to matter like fleas and bugs in general is my understanding. Not a clear time frame just “until conditions are right again.” Says if you have something for them to breed theyll stay alive indoors over winter.

Star Dog said:

Yes that seems logical bud, how could they get from one year to another without some kind of long term strategy for the long winters outside?

@FKH hey bud welcome to Riu.
Jfc the coco was left wet with roots intact.

Fwiw folk's I've still not seen any gnats since it's now getting on for 3 weeks.

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Good stuff hopefully that's the end of em

Star Dog said:

How can fungus gnats survive winter if their lifecycle is 1 month?

Hardy gnats survive winter half frozen

Todd Sformo discovered that the fungus gnat survives the winter by allowing half of its body to freeze.

www.uaf.edu

The readily available info isn't very extensive its only half accurate and very basic.

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Yeah it definitely is an area that could do with more study

I live in woods in the mid south USA and a good rain with mild temps will start up mosquitoes and gnats about any time of the year. Gnatrol, lots of air circulation and light mix has kept them away.

I can't remember where I seen it but someone mentioned recently "root It" plugs were guilty of spreading gnats around?

see larvea on the plug?

The 1st gnat larvea I seen were in root It plugs?
I mistook them for pot worms to start with which are beneficial but after a closer look I seen they weren't pot worms.

pot worms are just white worms they don't have a black head and they're smaller.

Something dawned on me I hadn't thought about, the plant in the photo above was a re vegging monster clone, I had it around 6mths and it never did re veg that's only 1 of 2 in my life that's not re vegged?
I'm wondering if gnats had anything to do with that?

skink#1 said:

Yo Homey...Hot Shot? Like pyrethrins or Hot Shot Bug Killer? I must be missing something. I spray Zymes lightly it's citric acid and enzymes or something benign I hope. I don't see it affecting taste or plant health. Some things you don't want to spray on your soil. When I see Hotshot I think cockroaches, bedbugs, wasps,ants and such.

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I was being a little facetious. I have fogged the room with hot shot but I've only sprayed 'over' the top of the soil when there were literally hundreds of them. It kills the shit out of the adult fliers. I was really missed at them when I posted that. Luckily, I seem to have them beat down for the moment. The 3 photos are healthy and I haven't seen any gnats after the pantyhose. I sprayed the top soil with peroxide solution before the nylons. The autos I did the same for 2 weeks and they are snapping back. I've been using Recharge each watering and they're greening back up except the one that turned purple. I'd never spray the plants but with these fkrs, I get stressed.

The autos are springing back from the gnats. I just need another month of peace and they'll be ready...I hope.

Star Dog said:

I can't remember where I seen it but someone mentioned recently "root It" plugs were guilty of spreading gnats around?
View attachment 5445917
see larvea on the plug?
View attachment 5445918
The 1st gnat larvea I seen were in root It plugs?
I mistook them for pot worms to start with which are beneficial but after a closer look I seen they weren't pot worms.
View attachment 5445919
pot worms are just white worms they don't have a black head and they're smaller.
View attachment 5445920
Something dawned on me I hadn't thought about, the plant in the photo above was a re vegging monster clone, I had it around 6mths and it never did re veg that's only 1 of 2 in my life that's not re vegged?
I'm wondering if gnats had anything to do with that?

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Ugh, seeing that larvae makes me sick. I designed a whole new setup to beat those little f*ckers. Couldn't get any treatments to work reliably!

Love the thread name. lol

I want to apologize for the poor and flat out wrong advise I gave earlier when I said to allow a freeze. I say comments after I posted and did look it up. Yeah those little fuckers can survive up to -60f.
I do use a fair amount of BT-i even in my composter and leaf mold cages so I'd bet that's helped me.

I imagine if the adult flyer doesn’t have a place to lay eggs, it will crawl off and die with a few hundres eggs still inside its abdomen. Instead of using the last bit of energy to lay, it will use it towards converting its body and eggsack into a protective cyst, with a special coating that cant dry out inside for months. Then later when the time is right and you add enough moisture, it will crack back open like a seed!.

Thats the way I see it anyway, and my best guess. Pretty sure thats how spider mites survive or over winter too..

Scientist very recently discovered that eggs did infact come first, before the chicken. That means the fungus gnat egg came first too, before the larva. That means they ARE inter-dimensional!?