Would be interesting to see how effective it would be.. Is peppermint the only kind of mint that is effective? Which forum did yo read about it?

Interesting. And possible. The mint plants due have a strong smell on their own and it might be something that the knats don't like. Makes me wish I still had my mint plant out in the herb bed. I'd be willing to try it as long as it's not going to bother the worms. They seems to not like pungent smells though. I wonder if anyone else has tried feeding anything else that's rather fragrant. I've hesitated in putting my fresh herb cuttings in there thinking they might not go over so well.