A colorful fly pattern known as the Royal Coachman Bucktail was my Grandpa Harry’s secret weapon. This conclusion follows two decades of observing his catch on the South Fork of the Walla Walla River.

A few weeks ago, I resurrected a fly pattern that you’ll probably recognize if you are among that group of now middle-aged fly fishers who took up the sport in the 1970s. We called it the “spider.” ...