The Stimulator pattern is a derivative of earlier stonefly patterns—the Improved Sofa Pillow (1940s) and Yellow-bellied Mattress Trasher (1970s). Many anglers believe the name Stimulator was given to the pattern by Jim Slattery, a Montana angler who renamed his Fluttering Stonefly pattern. Others contend the pattern was derived from the Trude style dry flies developed in 1903. However, the pattern was clearly popularized and promoted by Randall Kaufmann, a fly shop owner, angler and author in Seattle, WA and Portland, OR in the 1980s.[1]
Imitates
Originally tied to imitate large stoneflies, the Stimulator is also useful to imitate adult caddis, grasshoppers and large mayflies.[2]