What kills gnats in the bark?

[pbphut]

I have repotted all my orchids in a bark/charcoal/perlite mix and they seem very happy with it. However, there seem to be gnats living happily in the bark too. Since the 'chids are in the house, it's pretty annoying. Is there anything safe to both us and the plants that will work well? I've tried a "green" houseplant spray, but it didn't seem to help.

[WhiteRabbit]

I have soaked pots in mixture of equal parts rubbing alcohol, 409, and water with a bit of dishsoap.
I soak for about 15 - 20 minutes then flush the pot.

A mixture of hydrogen peroxide and water also works tho I am not sure of the dilution - perhaps someone else here can let us know

[Ross]

Those are probably the adults of fungus gnats. The juveniles live on fungus, etc. in the decaying bark. The best (and perhaps only effective) way to get rid of them is break the life span cycle. I use yellow sticky traps hung near the plants. There is really no effective pot treatment. Keeping the mix dry will help prevent the gowth, but sometimes this isn't possible.

[pbphut]

Thanks all. I'll give your ideas a try.

[nhman]

One can try the following:

1) Repotting into new media
2) Use of gnat bacillus (similar to that used in Mosquito dunks) that supposedly breaks up their life cycle.
3) The afore mentioned use of dilute alcohol
4) Yellow sticky tapes to deplete their populations

[WhiteRabbit]

I have also added pitcher plants and butterwort to my gnat aresenal

[nhman]

What species of pitcher plants and Butterwort plants do you use and how successful is this technique??
Do you use this as your only control method?

[Pantsonfire]

Look for a product called "mosquito dunks". You want the ones that contain Bacillus Thurengensis Israeliensis, it will the fungus gnat larvae when they eat it. I keep one in a big bucket of water that I then use to water the plants. Biological warfare on bugs.
Works like a charm.

[WhiteRabbit]

Originally Posted by nhman

What species of pitcher plants and Butterwort plants do you use and how successful is this technique??
Do you use this as your only control method?

No, not my only control method. Well I'd have to find the names of the plants - I know the pitchers are north american natives.

The butterworts haven't 'caught' anything as far as I can tell. I do see some gnats and flies in the pitchers.
I seem to have good spider control lol. And I have been experimenting with essential oils misted onto plant and surface of media after watering hoping this may have some 'repellant' effect. Seems to help - haven't seen larvae in the pots for some time *knocks wood* and while I do have some gnats it isn't as bad as it was

[Ray]

All of those treatments are working on the symptoms, not on the problem.

As Ross pointed out, the gnats are present because you have a population of gnat larvae living off of fungus growing on decomposing bark, and that's going to be a bigger problem than a few gnats.