IOBO Humpy
Originated by Jack Tucker
Hook: Standard Dry Fly, I prefer Barbless like the Fulling Mill Ultimate Dry, or Mustad R50XAP Size 14-20
Thread: 24 Denier Semperfli Nano Silk, or 18/0 Denier Nano Silk
Body/Wing: Natural Cul de Canard
I rediscovered the IOBO Humpy a few years back and it's earned a permanent spot in my dry fly box. "It Oughta Be Outlawed" — that's what the IOBO stands for, and the name isn't really an exaggeration.
Jack Turner originated this pattern, and what's remarkable about it is how little is going on. A hook, some thread, and a single CDC feather folded back on itself. No tail, no hackle, no wing post. That's the whole fly. It shouldn't be as effective as it is, but the CDC sits in the film the way a real mayfly does, and trout eat it with confidence.
I've fished the IOBO on Rapid Creek and across the Black Hills, on spring creeks and freestones, during Baetis hatches and PMD hatches and plenty of times when nothing in particular was coming off. It works. Match the size to whatever's hatching — or close enough — and you're usually in business.
It's also one of the easier dry flies you'll ever tie, which is part of why I like it. You can crank out a dozen in the time it takes to tie a few parachute Adams, and they're durable enough to fish hard.
Below you'll find the CDC, hooks, and thread I use for this pattern, along with the tying video. Tie up a few before your next trip — I don't think you'll regret it.
