San Juan Worm is the famous aquatic worm pattern used throughout North America. This subsurface fly matches natural worm forage in rivers and streams. Drift it along the bottom through fast runs or deep slots where trout hold. Its minimal profile cuts through current and stays in the strike zone longer. Tie it on heavy tippet for control in big water. The pattern holds up to repeated casts and abrasive riverbeds without failure. Load it into your box for consistent subsurface takes across varied North American watersheds.