Do you know the potato trick? Haven't tried it personally, but I believe it -- the story is that the larvae will be attracted to pieces of raw potato left on the surface of the soil. Leave it there long enough for them to get to it, and then pull it up and throw it away: they'll stick to it and you can get rid of a bunch of them all at once, before they ever get to be adults.

If you're serious about eradicating them completely, you should know that the life cycle is about four weeks long, so you might be doing all this for a while.

Here is a link that might be useful: About fungus gnats

Also pour some bleach down all your drains. Sometimes they set up housekeeping in their too.

If you have standing water around anywhere (humidity trays or whatever), get rid of it. Check all the bottoms of your pots and saucers to see if there's any standing water hiding in there.

Be sure to lay the sticky traps horizontally, not vertically like they are used for other pests.

Peppermint tea, huh? Hadn't heard of that one before.

I recently attended a lecture by an expert on using beneficial insects, and she was bemoaning how fungus gnats are becoming resistant to Bt, a natural bacteria used to kill them. Gnats are becoming more and more prevalent in the soil of plants our company buys from Florida, even from the good wholesalers. It is a serious problem. I would quarantine any new plants you buy, and try to buy potting soil that appears to have been stored dry, not out in the rain.

I think better than fly paper or sugar would be the little bee catcher bottles. Google it if you don't know what I mean.

Skip the hot water. If it's hot enough to kill larvae in the soil it would probably scorch the plant.

If you have water in humidity trays then add salt to it. It kills larvae of mosquitoes so I assume it would do for other stuff also.

Wow, you guys have great ideas..never heard of most of these tricks, but they sound ideal.
Jungle, sounds good to me..I'm thinking you're talking about sticky traps instead of fly paper right? Those w/glue on both sides???
Great ideas..if I ever get fg's I'll have to remember these tidbits..Toni

Yeah, thanks for the extra ideas everyone. Very helpful. It's a united front! =)

hopeful: Yeah, definitely the sticky traps. there are several types out there, the kind I got are little green plastic sticks that you put in the soil and two spots to put these yellow strips of sticky paper that stick out horizontally. It's definitely not fly paper, but I bet that would work too... these things are always looking for a new way to die. Again, I'm stunned the species survives at all since they actually seem to want to die... but I guess since "each female lays 100-300 eggs in batches of 2-30 each" (thanks for the link and info Mr Subjunctive), it's just the ridiculous number of them.

Anyway, I have no idea if any of the above methods work, but I'm going for the shotgun approach. If each method works even a little bit, then having them all going at the same time 'should' get rid of them. *fingers crossed*

Watergal: thanks for the tip about the drains... I had a few plants in my bathroom and the gnats love it in there. I barely see any or catch any around the plants, so that has to be it. thanks!

Greg*

PS T-minus 2 days until FG destruction begins. =)

What would happen if you put that 1/4 inch of sand and then put a thin layer of potting bark? It would look better I think. Except for cacti that is. I have some cacti and I think I'm going to put sand on their top soil. Would the potting bark be enough medium for the gnats to grow in? The bark wouldn't stay wet because the sand below it so I'd assume the gnats would die anyway.

If not you could put aquarium rocks on top of the sand. That is unless you like the way sand looks in your pots. I'm a bit OCD about it and insist on quality potting park on all of mine. Dirt just looks to cheap and all :)

The nasty little buggers are attracted to yellow so if you are going to put out bowls of water, put some yellow food color in it or use a yellow plastic bowl. I don't know if the sugar is necessary, they dive right into the plain water and drown anyway. I drench the soil with Knock-Out Gnats periodically (a BT product which is still working for me) to kill any larva.

I think no matter what, they will persist. I also have heard from many people that the leading brand of potting soil is often infested with larva and when the company was contacted they shrugged it off saying they did not claim to have a sterile product. If you bring bananas in from the grocery store or tomatos from the garden, I think you are renewing the population.

Sometimes I resort to a flying insect spray with pyrethrins and just mist it around the plants.

It's a constant battle. Bugs are the bane of my existance!

~Chris

Howdy Jungle Boogie: I am currently dealing with maybe the worst infestation of FG ever. For a bug that does relatively little harm to the plant, they sure are a nuisance.

Since we are always keeping the surface dry to make it harder for them, we can spread diatomaceous earth (D.E.) onto the soil. It works until it gets wet. The bugs landing onto it or emerging into it will be dessicated. This leaves watering sparingly (from the saucer, from the bottom, from the tray) to keep the plant from dying. As someone stated, emergency watering only.

Rotenone added to the water (and/or soaking the whole pot in water laced with rotenone) might work, but I have to try it. I am off to get the supplies to test what has been given here.

Randall Prue, Montreal Plant Doctor
Author: Keeping Them Alive

Here is a link that might be useful: Montreal Plant Doctor