fungus gnat problem, what to try next?

Discussion in 'Bugs' started by linky, Dec 5, 2016.


    linky Well-Known Member

    I switched to coco a few months ago and since then I have had bad fungus gnat issues. I am using mosquito dunks in the res and Microbe Lift Mosquito Control in the res's as well. I have yellow sticky traps for the adults.. Also for the past 3-4 weeks I have been misting pyrethrin on the coco surface when I see adult flyers.. so I basically have not seen any adults in at least 3 weeks now. I see one every other day or so and that is when I nail the coco surface with pyrethrin and it kills them off again. I am still getting tons of larvae in my 4 x 4 trays though, you can see them wiggle and hop around on the water surface. What can I use to safely kill the larvae once and for all?

    the dunks or the licrobe lift stuff is not working apparently (had had them in all my res's for a couple months now). I bottom feed in 4 x 4 trays.

    Growdict Well-Known Member


    Enots Active Member

    Beneficial nematodes

    linky Well-Known Member

    ordered some nematodes, will give that a try. thanks

    Enots Active Member

    No problem, I also throw some diatomeceous earth on top of my soil. Stuff Is like razors to them adult gnats. Plus it adds silica :clap:

    sammy2 Well-Known Member

    Crumble one of those mosquito dunks and spread it into the coco.
    In about 3 to 4 weeks and your gnats will be gone. It doesn't take much,
    so take it lightly with the dunk. One dunk can take care of a pond.

    Jubilant Well-Known Member

    I made a post about this in Rasta Roy's Introduction to Organics thread

    I will just copy and paste it so you don't have to search.

    "Diatomaceous Earth is a GREAT substance to leave powered and DRY for Fungus Gnat control. Make sure you use food grade D.E. or it is very hazardous to breath in. This will pierce those little larvae and kill off most the population in your soil if you let it dry out thoroughly between waterings.

    I had an issue with Fungus Gnats and I used D.E. by making a fine layer over the top of the soil then mixed it into the top layer (no more than 1/4 inch deep) then I places another fine layer on the soil covering the top but still a fine layer, then I place Yellow Fly Paper in the pots as well. With that trick and making sure soil dries fully between waterings left me with virtually no gnats in 1.5-2 weeks. I did make sure to replace the fine layer on top of D.E. after a watering as moist D.E. will not be effective as a pesticide."

    Antman15 Well-Known Member

    Fungus gnats don't hop around on the water surface. Springtails do though.

    linky Well-Known Member

    Not the fungus gnat itself, the larvae, they are tiny white larvae, when they are in the water left in the tray they will wiggle/hop around a little.

    Fastslappy Well-Known Member

    I use safer soap to kill the wigglers near the coco surface spray the surface & they all zoom to the top in a dance of death
    it's a fatty acid of phosphate or I use orange oil in a .5% solution of water & ISO alky
    take a spray bottle put 1/8" Orange oil on the bottom fill 1/2 way with iso alky & top off with water then a squirt of Dawn shake well , kills on contact will not harm plants or yer herd of benies but don't soak a plant or soil to the point where it's running off , as it is ISO alky
    get the pure organic oil here
    I've had my bottle 2 years now & still have 1/2 ,the spray makes a great kitchen cleaner & ant killer smells good

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