What kills gnats in the bark?

[Ray]

Originally Posted by WhiteRabbit

I have heard both they don't harm the plants and they do - I would rather be safe than sorry. And even if they aren't harming the plants I don't wish to have a gnat explosion lol

The gnats themselves do nothing. The larvae do no harm to the plants as long as they have plenty of fungus to graze on. Unfortunately, if the "goings are good" for them, the population grows pretty rapidly, they wipe out the fungis, and start working on roots!