little black flies

raylynn2(8a)January 6, 2013

I did not know where to post this but I have little fruit flies on all my plants they even get in soil. So I am wondering what they are, why I have them and how to safely get rid of them. Thanks in advance

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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

You probably have fungus gnats, which fly around a lot more and have smaller bodies than fruit flies. It's possible fruit flies came from something in your kitchen, then moved to pots when their original home disappeared, or just got in the pots from being outside if your plants were out for summer. I've seen a lot of both with potted plants and composting and fruit flies really stay very close to moist, rotting organic matter, not the peat, mulch, or even leaves likely in a pot. Peat/mulch/leaves are great for fungus gnat larvae tho, if it stays moist.

Either way, whichever they are, the soil needs to remain dry enough, especially at the surface, for the larvae to die. People also say watering with mosquito dunk water kills them. Make sure there are no dead leaves on the surfaces of the pots. Usually a sign your soil is staying too soggy too often. A fan on low can help keep the surface more dry, and make it just plain difficult for the adults to do much. Are you seeing yellow leaves/tips on plants?

    Bookmark   January 6, 2013 at 2:16PM
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No I have not see any yellow or any ill effect at all from the stupid flies they are just annoying. It might be the damp soil because I have all kinds of new babies that I keep well watered. I will try and let them dry out a bit but I also will get the dunk stuff what is it and where can I purchase it lol. I also wonder about the effects it will have on my newer plants I have a ton of a.v leaves and succulents sprouting and would be really upset if something happened to them

    Bookmark   January 7, 2013 at 1:07AM
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You can buy dunks in most stores (HD, Lowes and more) or on line; they are Made with Bt-israelensis (Bt-i), a highly specific biological pesticide

Sold in few different sized packages.

The flies don't cause yellowing of leaves, wet soil will.
The flies just like the damp environment as purple explained above.

This post was edited by rina_ on Mon, Jan 7, 13 at 8:38

    Bookmark   January 7, 2013 at 8:35AM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

Thanks, Rina. I don't like my explanation above. Peat, mulch, leaves are definitely rotting organic matter, but they are a slow type, a brown. Fruit flies need rotting greens, soft, moist all the time.

    Bookmark   January 7, 2013 at 10:45AM
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rhizo_1 (North AL) zone 7

To tweak the explanations...the adult fungus gnats don't do any damage; they're just annoying as they flit around. The possibility of real problems occur when the tiny eggs laid by those gnats hatch!

The larvae are small, whitish, wormy things that feed on the little bits of organic stuff (peat, etc.) and tender plant roots. They can be seen if they come to the surface when you water. These larvae, of course, develop into more flitting adults.

The 'dunks' are composed of a biological larvacide, a bacterium called Bacillus thuringiensis-Israelensis. Bt-I has been used for generations to control the larvae of certain insects in the Diptera order....mosquitoes, gnats, blackflies, and the like. The larvae of all targeted pests begin their lives in aquatic or semi -aquatic environments.

Dunks work well for FG larvae, but the product needs to be dissolved in water and applied on normal watering day, not just sprinkled on top.

The long term solution includes changing or altering your potting medium to something very fast draining and porous. I never have fungus gnats, and haven't for many long years. My mix is very coarse textured....I can water freely and often without fear of the medium staying soppy.

    Bookmark   January 7, 2013 at 1:08PM
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Thanks everyone I'm going today to get some. My husband will be so happy he's been hollering about the stupid flies lol I will also maybe switch my soil it is all fresh but maybe the type should be differant again thanks to everyone :)

    Bookmark   January 8, 2013 at 12:04PM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

If you have fungus gnats in pots with AV's & succulents, that's too much moisture for sure! The flies are annoying but excessive sogginess can/will kill plants. No doubt it is really hard sometimes with plants that don't wilt. They will feel less sturdy though. That would be a sign you went too long, I wouldn't risk dehydrating a plant to death to get rid of FG's, just to keep things in perspective. If you have them in multiple pots, it's going to be difficult to have a drought in all of the pots simultaneously. I trust the folks on here telling you the dunks are OK.

The less excess moisture your soil holds, the more margin there is for error, as well as NOT being the haven for fungus gnat larvae. It sounds like you enjoy watering, which is great, so I would strongly urge you to investigate "potting mixes" more in depth, pun intended. People make them out of various "ingredients" but the principles of how they perform are the same if done correctly. The more quickly a pot dries, the more often it needs water, which keeps things fresh and flowing, and fun for someone who likes to water - AND have that be of benefit to the plant, not a detriment. When the temperature is cooler, plants use water much less quickly, although the heat source inside can dry the air and balance that out some.

The pics of the soil in this discussion are really nice and clear. Some good reading material, more soil and plant pics.

    Bookmark   January 8, 2013 at 2:17PM
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I use yellow sticky traps, but this link says red ones are better-

Here is a link that might be useful: Fungus Gnats and Shore Flies - UMASS

    Bookmark   January 8, 2013 at 7:09PM
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