Light Cahill

By the time the spinners are down the fly has finished its job and is simply lying there, spent, wings flat in the film, going nowhere. Trout know the difference between something alive and something that's stopped trying, and they take spinners with a quiet, unbothered sip that's easy to miss if you're still watching for something splashier. Look for them on the glides and in the slack water, wherever the current gathers what's left.

• North America — EastPresent

Stenacron interpunctatum , the stenacron mayfly , is a species of flatheaded mayfly in the family Heptageniidae. It is found in all of Canada and the northern and southeastern United States.