Here’s a tricky question for you. If you get this one, you should be a guide …

Andy was fishing the Bighorn in May with his favorite guide, Dan. The streamer fishing was fair. The mayflies were sparse. Nothing really happening in terms of terrestrials at that time of year. But there were midges. Tons of midges, rafting and swirling in every current, all over the river. And the trout were slurping away on the surface like demons. Now, as we all know, midges are very small, and midge flies are hard to tie. Andy found one size #24 gray midge in the corner of his flybox. It was a spot-on facsimile of the naturals that were buzzing around his head, flying into his ears, and up his nose. He cast that fly, and nothing happened. He made another cast. Nothing. The fish ignored it, but kept slurping away at naturals. Finally, on this ninth cast, a fish rose, ate his fly, and promptly broke the tippet. “Dang, I don’t have anything else that small,” Andy admitted to Dan.

“Don’t worry, that wasn’t a very good pattern anyway,” said Dan. “Here … let’s try this.” Andy gave Dan a “You’re kidding me” look as they tied on the next fly. But after one cast, boom, they hooked a fish. Andy was a believer. What did Dan tie on, and why did it work?