Wow this is an old thread resurrected! This was by far the only time I experienced them, and I know exactly what green flying things you are talking about. I have never seen how long they live or where they go but I have seen one hatch on the surface of the water. It was wicked, but I don't really like bugs, so icky at the same time. The brown things in my filters, well I was able to rid myself of them by doing more thorough cleaning of the substrate and as I got them building up in my sponges, I cleaned those out as well. I did notice if you let your sponge soak in water, they would come out. I was really freaked out when all of this was going on, but nothing was affected by their presence. I no longer have these in my filter media, though I occasionally do see some in the filters at the store where I work part time. I just chalked it up to I wasn't cleaning well enough and when I started doing a better job, and feeding the tank less, they went away... Hope that helps.
I always see these little tiny bugs jumping around on the surface of the water on every tank I have. No idea what that is, but it is annoying just as much. I was told I should take it as a compliment, since they do not inhabit bad tanks