Craig Mathews off Blue Ribbon Flies in West Yellowstone and his former partner John Jureck “invented” the Sparkle Dun some years ago.
Mathews tells that he and John were crossing a fence near The Ranch on the Henry’s Fork when they caught site of “sparkles” on the water in a little eddy. Upon inspection, they found the sparkles came from the shucks of emerging mayflies.
When they returned to their shop, they tried sparkly material for a “trailing shuck” on a comparadun, and used Zelon for the “shuck”. They had come up with the Sparkle Dun.
Their observation, combined with the knowledge of a mayfly’s stages and characteristics of emergence led to the very effective pattern - the Sparkle Dun - an emerger or a crippled dun.
The concept has been extended to many other patterns such as this type of a cripple pattern
I appreciate, and take advantage, of the discoveries of other fly fishermen.