I read about the use of this in controlling fungus gnats and tried it out with success. It certainly works on well established plants and I have been able to save a lot of my indoor plants.
http://hubpages.com/hub/Hydrogen-Peroxide-for-PlantsIt was more difficult to use on my very young seedlings as I couldn't allow the soil to dry out between waterings. It seems that hydrogen peroxide only works for a few minutes and then breaks down. With adults flying around laying eggs you need a few hydrogen peroxide waterings to eliminate them all and I couldn't water my seedlings that often.
I have just introduced nematodes into the pots with seedlings. Let's hope this works as I have lost lots of seedlings over the last few weeks. Fingers crossed.
