One legendary insect--enormous, white, and exceedingly rare--attracts trout of such size that they couldn't possibly exist in the world as we know it. But in Heywood's classic novel, such things can and do exist.
Protagonist Bowie Rhodes, UPI reporter and expert fly fisherman, had learned of the snowfly early in his childhood. It hatches every seven to ten years, never on the same river twice, bringing to rise trout so huge they would have to...