UNDERBELLY BEAD PHEASANT TAIL NYMPH FLIES
The Underbelly tungsten bead Pheasant tail nymph Maybe the best all-around mayfly nymph in your fly box. It does a great job of imitating MOST of the mayflies.
If you see fish darting back and forth beneath the water simply they are grabbing rising mature mayfly nymphs as they're just swept past by the current. Must have in your fly box. Fly fishing hook size 16.