This Sparkle Dun pattern is highly visible in low light and imitates both duns and spinners.
Late-season light Cahills (McCaffertium modestum)—traditionally called Cream Cahills—often hatch sporadically the last hour or two of light. The trout will rise to these duns, but they sometimes prefer the spinners, which return right at dark.
Cream Cahills normally hatch before dusk and then spinners fall at dark.
In this great video from Tightline Productions, Matt Grobert, an author and blogger, shows his technique for creating this useful, yet simple pattern. I always enjoy the little tricks that make adding materials easier. The way Grobert makes a couple wraps around the shuck and then pulls it into place makes perfect sense. I like the open hook shank behind the eye, as well.
Cream Cahill Sparkle Dun
Hook: Standard dry-fly hook (e.g. TMC #100), size 14.
Thread: Yellow, 8/0 or 70 denier.
Wing: Elk body hair, cleaned and stacked.
Shuck: Light amber Zelon.
Abdomen/Thorax: Cream rabbit-fur dubbing.
Head: Tying thread.