If I were a smartalec I'd ask "Ever heard of birds and bees?". However, I am not like that.
The vast majority of insects can fly and so they flit about and lay their eggs anywhere they choose. We see the effects later, after the eggs hatch and the larva or caterpillar start feeding on our property and possessions.

I mixed up a batch of soil for some bamboo seedlings I had started. Used a small bag of soil booster from the local lumberyard in the mix, supposebly sterile. I didn't really pay attention to the little flys buzzing around as I was doing it. Anyway, as it turns out they were fungus gnats, and I have been battling them ever since(4 years). They don't bother the big stuff, but are death to many new palm seedlings. The moral being, watch the soil carefully when you repot. It sounds like maybe thats where your bugs came from. There are alternatives to poisons, but you need to know what bugs you're dealing with. Safer soap & neem oil are both pretty general, low impact insecticides. Good luck.

If I were a smartalec I'd ask "Ever heard of birds and bees?". However, I am not like that.

Make note to myself...remember this line......lol :-)
Only problem, it takes the fun out of being a smartalec....lol

jenf,
fungus gnats themselves don't actually cause harm to plants. They are benign. The reason fungus gnats are there at all, is because, they thrive in matter that is uniformly too wet in the first place. Orchid growers know that if they see fungus gnats, they are probably overwatering. Overwatering leads to fungus. Fungus can lead to damping off of palm (and other plant) seedlings.

The gnats themselves are a symptom, not the primary problem. If you still have them after 4 years, perhaps you may need to evaluate your watering program.

Just an aside...a very easy way to get rid of the ones buzzing around is to set out small saucers of household ammonia. The gnats are drawn to the smell of it, fall in and die. But the only way to get rid of the ones in your plants is to repot in a better darining mix and reduce your watering to a level that's not conducive to them being able to survive.

I'm aware that the flys do no damage, just a irritant. I'm also well aware of the over watering problem. But the larva eat organic matter, sometimes the roots of tender seedlings. Damping off is a problem with lots of seedlings but not so much with palms. When I check the dead seedlings, you can see where the tap root has been chewed, the larva are visible with a magnifying glass. I found an article somewhere that said palm seedlings are paticularily vunerable for some reason. We have allowed the soil to dry out to the point of almost death in an effort to control them. I've done my research, there are beneficial mites and nematodes that I've experimented with. For the moment we seem to have it under control. My point was that the purchased soil booster came heavily infested, and then spread to all our other indoor plants. It can happen. We keep the sticky yellow strips about, just to monitor them, I only use soiless mix such as promix or sunshine mix and no longer add anything. I haven't tried ammonia, I'll have to pick some up. I have found on this forum that I'm not alone, especially with the Moso bamboo seedlings.

Wow, I have never had that problem! I feel for you. For some reason, wherever I have had fungus gnats, and corrected the watering problem, mine went away and didn't come back. Mainly I have always gotten them before I had a greenhouse on plants that I bought during the winter and stuck in the house to keep over til spring, and the mix they came in was not the best draining as it could be. Usually a quick repot and decreasing water was enough to eradicate them permanently.

The problem insect I always have the worst time with is mealybugs. Some of my plants are just magnets (like Ti leaves and heliconias) and they end up getting on my palms as well. For my very few houseplants, I just set the infested plant outdoors for a few weeks and usually predators in the yard handle it for me, but in the greenhouse I have to follow a pretty rigorous prophylaxis with Neem Oil and a lot of "on the spot" treatment with soap spray.

We also used Neem oil, it seems resonablely effective, except as you say watering is an issue, and the neem oil needed to be watered in. Again like you, once they go outside, it seems way better. We have a decent greenhouse with fans now, and are using fans in our cold frame, I beleive this also helps. I should have just repotted or recognized what I was dealing with in the first place. But I felt as you, that they were just an irritant more than anything. Once the palms are a year or two, they don't seem to be bothered. On the other hand I have never dealt with mealy bugs, they look nasty. We get spider mites and aphids, but thay are reasonably easy to deal with using Safer soap. We are at the moment doing a rigorous routine of insecticides, then are going to give it 6 weeks, then introduce some beneficial predatory bugs. Hoping that it will be more of a pro-active environmental approach. Thanks for the advice on the ammonia.

Your story reminds me of something that some on the Florida forum posted a year or so ago. In some counties here in FL, on a general basis and ESPECIALLY after a hurricane year, like 2004, counties will have the need to dispose of all the tree debris that gets blown down and has to be processed without putting it into a landfill, so they will give away their glut of forestry products in the form of free mulch, which is something that almost every yard in FL uses year round. This person was from either South or Central FL and got a load of mulch that was heavily infested with FIRE ANTS. Needless to say he was terribly PO'd, as anyone would be!