The Sparkle Dun is Craig Mathews' take on the Comparadun: same fanned deer-hair wing, same hackle-free body, but with a sparse Z-Lon (or Antron) tail trailing behind as a shuck. That tail reads as the nymphal shuck the mayfly is still dragging as it climbs out to hatch, which is exactly what trout key on during a Pale Morning Dun emergence.
PMDs run pale yellow to sulphur, so tie or buy this in those two body colors, sizes 14-18. The hatch comes off in the warmer part of the day when water sits in the 54-64F range - late morning into early afternoon on a Western tailwater or spring creek.
Fish it in clear to lightly stained water, low to normal flow. With no hackle the fly sits flush in the surface film, so it sells the take but can be hard to track - watch the spot where it landed and set on any sip in that lane. Dead-drift it down a feeding lane to a working fish. If trout refuse a standard upright dun, the flush profile of the Sparkle Dun is usually the fix.