Little black nats flying around?

[greenpassion]

I have recently gotten into moss terrariums, using clear glass vases, and the moss is from my woods here in VT. These are situated on and under a glass shelf that holds my orchids of several varieties, all in S/H. Thus far I've never had these "fungus knats' before, and I think I've inadvertently introduced them to the area via the moss. Will these hurt my orchids? And how do I get rid of them, without if possible, getting rid of my little moss terrariums?

[NatalieS]

The adult fungus gnats are not a problem - it's the larvae which could pose a serious issue. I don't know if the larvae would live in moss though, so it could just be that the adults are feeding (perhaps someone else can confirm/disagree).

I'm not entirely sure what's the best way to get rid of them, but I think an insecticidal soap will do the trick. If insects are soft-bodied soap should kill them. Even perhaps using Bud's mix of dish soap, tepid water, and cinnamon extract to soak the moss might do the trick in killing any larvae. The mixture won't hurt the orchids!

[Oscarman]

Anytime I have had fungus gnats, I use bright yellow Sticky-Strips strategically placed. Eventually the adult all get caught and can't lay more eggs.

There are more rapid, chemical methods which I prefer to not use.

[The Mutant]

So THAT'S what these buggers are called! Ever since I bought pre-mixed orchid compost, I've had problems with these guys swarming my flat. They came with the compost and I'm never buying that brand ever again.

So the larvae can be harmful to the roots? I've better get rid of them ASAP then! What kind of home remedy can you tell me about? Soap and Bud's mix (where I think Bud's mix should work well), anything else? They bug the...*coughs*... out of me but I haven't bothered trying to get rid of them since I figured they didn't harm the roots. Now that I know they do, it's war though!

[greenpassion]

Thanks all for your responses. Now, another question. My orchids and african violets are all in S/H, using hydroton as the medium. I do know that the knats didn't come from them, as I've had these guys,(orchids and such) all in S/H for close to 9 months. Suddenly I have the knats, days after I created the little moss terrariums. That being said, I am hoping I'll hear from someone that the fungus knats won't reproduce in hydroton. It's not soil in any way. Wonder if maybe Ray might see this post and offer some info...?

[Oscarman]

Not an expert, but 70% of my plants are in an expanded clay product of some brand, PrimeArga, Hydroton etc. Can't see how gnats would survive in that. Had gnats with plants in dirt, never in S/H.

I thought the larvea mostly fed on small fine roots in dirt type media.

Remember, I am not an expert!

[NatalieS]

Originally Posted by Oscarman

Not an expert, but 70% of my plants are in an expanded clay product of some brand, PrimeArga, Hydroton etc. Can't see how gnats would survive in that. Had gnats with plants in dirt, never in S/H.

I thought the larvea mostly fed on small fine roots in dirt type media.

Remember, I am not an expert!

I am not an expert either, but I agree that it seems pretty unlikely for fungus gnat larvae to survive well in expanded clay.

Just as a matter of interest I went searching on one of the UK orchid forums and found a thread about people using cat litter as a potting medium!! Apparently fungus gnats hate it, and the results for people were pretty good. I might experiment with this myself...

[Discus]

I find that sundews (providing you have enough light) provide excellent natural "sticky traps" - I've grown a whole bunch from seed (they grow easily) and the fungus gnat population has crashed!

Their larvae are supposed to feed on fungi and decaying organic matter; assuming your S/H pots aren't full of non-S/H adapted roots that are rotting, there would be little to support them; it's possible some hitched a ride (as larvae) in your moss, and that might well still be generating them. I got some sheet moss once that turned out to be infested with these, particularly when I kept it damp in an attempt to persuade it to be alive. :/

There is apparently some evidence for these beasts spreading fungal diseases; a good reason to get rid of them even if the little buggers flying about and perhaps munching on your roots wasn't reason enough! see UCONN IPM: Greenhouse: Insects: Fungus Gnats

[orchidsarefun]

yep - Drosera/sundews are great. I have one that I purchased last month and I can see all the gnats it has "caught". Can recommend if you can manage its growing requirements.
Between a jumping spider, a drosera and a venus flytrap I think I have all 3 grow rooms covered.

[greenpassion]

I'd never heard of them until you guys posted about them. So of course, I want some. Lots of questions. How many might I need? If you go to the post 'Growing masdies in glass bowls' I have posted a photo of my set up, which isn't very large. My plants are on a glass sheet that's 4ft long, 17" wide. They aren't crowded, but there isn't much more room for more plants. (I have them under lights as I have no space for window sill growing.) Under the glass shelf I have moss terrariums I made, (most likely where the nats came from) and they get the light that comes thru the glass.That said, if I bought 3 potted drosera's, and put them amongst the orchids, or under the shelf, would they be alright? I've already read up on them (some) and it sounds to me that the light that has my phals and oncidiums blooming will be ok-but what if there's not enough food? (fungus nats) Also, I wonder, (and I'll be sure to ask this question in the S/H forum) if I could grow these drosera's in S/H? : It sounds like S/H might be ideal as they like the moisture around the roots. Anyone have answers for me?? dunno: