Emerging midges like to attach their tails to the surface film and lever their heads up through the meniscus, one of the hardest things to imitate. I have had some success tying a small strip of white foam on top of the shank, sticking out both ends after the body is added.A very small unweighted chironomid might work. Like this, and put floatant on the gill tufts. That you're seeing tails makes me think they're taking things a few inches beneath the surface, so you could try suspending something beneath a very small indicator or another fly. A griffith's gnat is a pretty darn good fly for midges and should make a decent indicator fly too.