Along with the buggers mentioned and muddlers (on top-grasshoppers?....underwater-sculpin?) and a few small poppers, this bug seems to be real effective where we fish smallies in Ca. Mainly the Sacramento R., L. Shasta, and the Russian R.
But then we find it to be quite effective when ever and where ever any fish are munching minnows, from smallies to stripers to LM's to bluegills to......you name it.