Small flies living in soil

Discussion in 'Bugs' started by AurelijusVeryga, Dec 9, 2017.


    AurelijusVeryga Member

    Hey guys,
    our plants are in week 4, they are doing great, the only problem now is small flies that are living in the soil. We tried to get rid of them by using stickers and also green soap spray. It helps to reduce the number of flies but doesn't help to get rid of them entirely. Any suggestions on how to do that?

    Also, maybe you have any advices on upgrading our growing conditions for further growth stages? We have 3 t5's, a fan blowing 24/7. we are growing the plants in the soil. Always keeping the temperature of the room above 70 Fahrenheits. on week 3 they received their first nutrient feeding, planning to do the same on week 5.
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    Colo MMJ

    Colo MMJ Well-Known Member

    Soil gnats most likely. Hopefully not root aphids which are worse. Both can turn into flying bugs. I am trying to thing of something that is inexpensive.
    ColoradoHighGrower likes this.

    GreenLogician Well-Known Member

    a.k.a. Fungus gnats.
    They are harmless in small numbers, but if the conditions are right they can balloon to plague proportions.
    Then the tiny nibbling their larva do on plant roots adds up.

    Stop that happening by letting your pots dry out more between waterings.

    Getting rid of them entirely is pretty difficult during a grow, between grows is your best chance.
    If you must by bags of potting soil that have been stored outside, don't get any with fungus gnats hanging around them
    ColoradoHighGrower and Colo MMJ like this.

    Huckster79 Well-Known Member

    Get em in coco all the time as we dont do dry em all the way... misquito dunks, its organic as its just bacteria... put a piece of a dunk in your water hfor a few days, works wonders...

    Works great if u refill ur water container right after using it and putting a dunk in so it soaks till next water, save em too as they last long time....
    Colo MMJ

    Colo MMJ Well-Known Member

    Good stuff man. Say if you do a hand water drench with a 1 gallon watering can. Drop the dunk in there for 24 hours while, pull it out and maybe put in a resealable plastic bag???
    Or put in the second can??

    Any idea if it will kill root aphids in coco/tupur? Thanks. :grin:

    Huckster79 Well-Known Member

    Id say throw it in next can or dry it back out, then re-wet whenever.. idk how you know when they dont work but i loose my lil chunks often enough not an issue for me. im not sure all that particular bacteria kills but fungus gnats definetly....
    Colo MMJ likes this.

    Huckster79 Well-Known Member

    Glad to here you arent nuting them to death as most new (and experienced) ppl often do.
    Be on look for symptoms of wanting more food when ur a light nuter, once you see it
    Prob want to prepare more light for flower, hows the budget for that? Theres options for all budgets...

    Seriously consider looking into coco and breathable pots like smart or air pots... roots love both and you really cant overwater with that set up.
    Colo MMJ

    Colo MMJ Well-Known Member

    I read a few threads on other sites and dunks supposedly do not have the horsepower to kill root aphids. Those f'ers are hard to kill.

    Thegermling Active Member

    I currently have the same issue as you man! I read that BT ( Bacillus Thuringiensis especially the sub species israelensis) should kill fungus gnat larvae. As for the adults, they dont do any damage themeselves just the larvae. It says to apply everyday for 21 days, then weekly, I thought It was less than that! I'll let you know how it goes.
    Tom Tucker 313

    Tom Tucker 313 Active Member


    deadskunks Member

    Uggh. I've been dealing with these fucks for like 2 weeks now..Hard as hell to get rid of. I tried sand as top dress letting eveyrthing dry out ,neem oil nothing works.About to try bti right now. It's literally been war. They are attracted to light, moisture ,the color yellow. they feed on dead plant material. They are quick and annoying when the get in your face (most likely attracted to your warm moist breath) but are harmless to humans, terrible for your plants roots.

    OrionNZ Member

    diatomaceous earth and H202 are the only things i know that is not potentially harmful

    Cold$moke Well-Known Member

    Ahh yea bring on the fungus gnats ;)

    How i got rid of them is i got rid of my co co lol

    Seriously they will hang out in dwc too just chilling and nibbling on yer roots lol

    More of a pain in the ass then anything

    How much sand did you put on top? I think it needs to be about an inch

    I also suggest h2o2 treatments as its relativley harmless to the plant in low doses.

    Other then that I honestly cant rember how i got rid of them except theres no dirt allowed in ny room coco included lol and i keep my rdwc pretty tight and clean.

    ColoradoHighGrower Well-Known Member

    Week 5, going on week 6, should i bother fighting them??

    Thegermling Active Member

    Yeah, they can still lay eggs and damage your plants roots.
    ColoradoHighGrower likes this.

    AAjax Active Member

    Get some gnatrol and your problem will be solved. That and stop over watering.
    ColoradoHighGrower likes this.

    ColoradoHighGrower Well-Known Member

    Thanks all- appreciate all the advice! definitely feel like i have not been over-watering, waiting for real light pots, and a good droop each time. I ended up using rosemary oil spray (~2% mix) on the soil surface and has worked great! Not even sure if i need to reapply, but will just to be sure any hatching ones get it too, kill the cycle...

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