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Need help with gnats and gnat larva eating my seedlings and plants please.


New Member
1st time grower soil. Have gnats which suck but the larva are the problem eating my seedlings and plants. I am at my wits end and would really appreciate the help.



Well-Known Member
High DixieDank, I've got em too. I've knocked them way back with a combination of Azamax drenches, Eco Smart spray, and Mosquito Dunks.

I'm keeping mosquito dunk crumbs in a 5 gal bucket of rain water with an airstone. I keep replenishing the water when ever I use it for watering. I've got some in the rain barrel, too!

I still see some solo fliers, but not clouds of them anymore :439:


And welcome to 420 :welcome:


New Member
Probably white flies. I suggest hanging yellow cups covered in tanglefoot. They are attracted to yellow, and will go for any yellow leaves.

As far as seedlings are concerned, go ahead and use pesticides. Also use bombs, as long as the seedling are in a separate room from any mature plants. Discard the leaves from the seedlings affected by bombs/sprays come harvest time.

Hope that helps.


New Member
Thanks for the welcome and i will try your suggestions as well as HorseBadortiz, i really appreciate the welcome and the tips this sucks but as long as i get them up and out before 420 new year i should be able to deal with it, i was just hoping to keep a few for flowering indoor but i may just transplant out and grow AK and Jack indoor so the larva will get out. I only have them in my closet but it hurts my feelings to loose such a vigorous acclimated strain due to a gnat larva eating my roots and stalk. I'm sure you can understand. By the way i appreciate all help and will probably need more before all said and done.

"Sacred cows make the tastiest hamburgers." — Abbie Hoffman

JJ Bones

Nug of the Month: Feb 2013
I would recommend changing soil if it's very bad, if this is affordable for you.

Otherwise, I would get beneficial nematodes which will kill your larvae. Azamax, as previously suggested does work well. Also Sierra Natural Science, whom are 420mag sponsors have a product specifically for your problem.


New Member
Would Premethrin kill gnats, aphids, white flies, and other insects without harming my outdoor plants in veg?


New Member
Hey Dixie,

I use Care Free enzymes Plant Protector to get rid of any pests. It works great. I have not had any problems with spider mites, whitefly, thrips or aphids. Slugs and earwigs I use diatomes. These are both organic, kill the pest and won't harm the people ingesting the mmj. And you can use both all the way thru harvest.

Good Luck


Member of the Month: July 2012, July 2014 - Nug of the Month: July 2012
I had a very bad infestation of larvae in one of my soil plants and tried everything: azamax, azatrol, neem oil, pyrethium, mosquito dunks and overall the best advice I could give you would be to pick up a steamer...the kind you use for clothes...(this would be very time consuming if you have a large grow, but works with smaller).

Take the steam cleaner, heat it up, and take a spoon to pull back the top 1-2" of soil on your pots. Do this after a watering which I found bring's the larvae up to the top of the soil... After pulling back the soil, use the steamer to steam the soil, make sure to cover all of the top of the pot....this will instantly kill the larvae...I've done it, and it works!!!!...

After fully steaming the topsoil...you should not see any moving larvae......it fries them instantly.... Follow up with a soil drench of Azatrol or Azamax and mosquito dunks and let the soil fully dry out....upon your next watering...pull back the soil and check to see if there are any larvae in site..... I did this method to a chemband plant that was infested and so far I have reduced the larvae population in my soil to almost none....

Remember that the fungus gnat has a life cycle of around 30 days, so you can't just do one treatment and expect results....you will have to do 2-3 treatments spread over a month to fully rid yourself of these buggers.....

I also would highly recommend yellow sticky cards....they work for catching and killing the adults....I put them all over my grow up...hanging above plants, below foliage, and even across the tops of my pots..... The adults lay around 300 eggs at a time...so if you are not killing the adults....then you will continue to have the problem...


Member of the Month: July 2012, July 2014 - Nug of the Month: July 2012
Also found out by reading and searching the internet, as well as personally using......and it works great!!!

heat up some water and make some peppermint tea, drop a cigarette or 2 into the hot tea water and wait till it cools down, add in a few drops of the hottest habenero hotsauce you can find...the kind where 1 drop burns your tongue....and then add in 10ml of neem oil....put this in a spray bottle....shake it well and apply to pots and soil...I wouldn't advise spraying your plants directly because I have heard that some plant's do not do well with nicotine...if you do, spray just one leaf and see if it has any negative effects....

Use this to spray your pots and top of the soil...I did this and within 1 day, saw no more adult/teen gnats at alll....not even one!!!

Dankafied Rob

New Member
Yellow sticky traps (for the flyers), Safer Yard and Garden + Safer 3 in 1 spray, both can be used as a foiler spray and or top soil spray (should be applied at night/dark hours) Neem Oil, and AZAMAX for the larvae growing at the bottom of your pots.

With this mix you don't need to mess with the Wacky Tobacky.
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