I must destroy them!

ssadams7700December 24, 2010


I have a gnat / gnat larvae infestation. Little flys and 2mm worms that will eat the root system of my VFT and sundews when they grow from seed. I have the fly paper and glass of vinegar as my front line attack wright now. Here is the problem... The net says to cover soil with a cm of sand to prevent gnats laying eggs and proliferating. That is a negative for me because I do not have mature plants and when removing the sand after the gnats are dead, it would be impossible not to remove the seeds that are waiting to germinate. In addition there is a nice little carpet of moss that has begun to grow. Oh yeah, I don't like harsh pesticides. Any suggestions / ideas?

Thanks Scottt

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In my experience, the potential harm of fungus gnats and their larva is overstated. I have successfully germinated thousands of sundews, Sarracenia and VFTs with swarms of fungus gnats buzzing around them, and their larva visibly present in the soil.

I was anxious about it at first. I attempted to keep my plants under humidity domes, and even tried to pick-out the larva, but I eventually gave up. To my surprise, there was no noticeable increase in seedling mortality rate. Perhaps I just have an extremely passive type of fungus gnat in my greenhouse.

If you really want to go-after your infestation though, it's a good time of the year to do it (assuming you're in the Northern hemisphere.) I don't know what else you're growing, but if it's just VFT seeds, I recommend starting fresh. It's very early in the season to be germinating them anyway, so I would just remove the seeds and store them in the refrigerator. If the source of the gnats is just that particular soil, I would discard it and start with fresh soil. Just to be safe, I would boil the new soil for several minutes to remove any potential infestations it may have.

If you want to be extra safe, you can then cold-stratify your seeds in that soil inside a refrigerator where there is less chance of infestation. When Spring hits, you can finally put-out your seeds. They should be sprouted and fairly large before any new gnats show-up.

    Bookmark   December 24, 2010 at 2:24PM
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taz6122(N.W. AR.6b)

A mosquito dunk containing Bacillus thuringiensis in your watering jug will do the trick and no worry about harsh chemicals.
You are right in that a large concentration of gnat larvae will destroy young seedlings. Don't keep the soil too wet in the future.

    Bookmark   December 24, 2010 at 3:19PM
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Can you please suggest a good BT pesticide. I am not sure which type I should use. I did a google search for mosquito dunks it looked like small disks you would put in a stagnant pool which does not seem like an accurate dosage to place in a 1gal. or less, watering jug. What about a product like Bonide Thuricide Bt Concentrate or any liquid/dust that could be measured precisely? Will any Bt pesticide work? I am unfamiliar with this kind of stuff, thanks.


    Bookmark   December 25, 2010 at 3:19PM
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Put one quarter of one in your watering can. It will not harm the plants at all. For the adults use sticky traps. The Bonide stuff is o.k. too. I use the dunks.

    Bookmark   December 25, 2010 at 8:35PM
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How about Neem oil?

    Bookmark   December 26, 2010 at 9:42AM
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Here's a good video from Sarracenia Northwest:


    Bookmark   December 26, 2010 at 2:01PM
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taz6122(N.W. AR.6b)

I wouldn't worry too much how accurate the dosage is but if 1/4 works for tommy, that's what I would suggest. I doubt using the whole thing would hurt your plants though it would be a bit wasteful.
I wouldn't use neem on seedlings.

    Bookmark   December 26, 2010 at 4:05PM
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I thought Neem Oil was for fungus. Can it be used as a insecticide? What else can it be used for?

    Bookmark   December 31, 2010 at 9:13PM
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taz6122(N.W. AR.6b)

It is an insecticide with some fungicidal properties. I wouldn't rely on it for a fungus remedy. It is more of a preventative as far as fungus. Depending on what it was made from ex. seeds/bark/leaves there are many uses from dental/gum/skin problems to insect control. The insecticide is made from the seeds.

    Bookmark   December 31, 2010 at 9:46PM
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