Hiram Brobst of Palmerton, Pennsylvania created this pattern in the 1920s after spotting an old unnamed English sedge pattern from the 18th century. He altered it a bit to work on Broadhead Creek near Henryville, PA.
The fly did well in Pennsylvania trout waters and eventually got the name the Henryville Special. Basically a sedge type caddis pattern, that has become popular throughout the country for the last 100 years.
Hook: #10-16 1x long dry fly
Thread: Black (or brown)
Body: Olive dubbing
Body Hackle: Grizzly dry fly, palmered
Underwing: Mallard flank fibers
Overwing: Mallard quill slips
Hackle: Brown dry fly