In April and May, the big stoneflies begin their shoreward migration and that makes them more vulnerable to trout. This pattern combines sparkle, movement and a buggy profile with the kind of weight that drops the fly to the bottom in a hurry.
Fish the Benham Falls Special beneath a strike indicator, letting the current tumble the fly downstream through riffled water. Strikes will be subtle, so watch for a slight movement to the line or a flash of a fish rolling. For more excitement, tie a dropper off the hook with a No. 14-16 beadhead nymph.
Tie this pattern on an extra long nymph hook with a sideways bend at midshank. For the tail and antennae, use black Flexi Floss. Slide a black cone-shaped bead to the head, then lay an underbody of lead wire. For the body, wrap Ice Dub and draw a single strand of blue holographic tinsel up each side of the body, then lay pearl Diamond Braid over the top. Rib with black wire. For the thorax, wing-cases and legs, use Ice Dub, Thin Skin and partridge.
— Gary Lewis, For The Bulletin