As with most of Brown's flies, there's not much detail, just a few pics; he makes a living selling his patterns, so that's certainly fair. This one can be fished as an emerging mayfly, caddis or nymph/pupa with just a few streamside modifications; scissors, nippers (or teeth) can be used to create the effect you're looking for.
hook - Dai Riki 135 #16
thread - UTC 70 brown
tail - pheasant tail
rib - wire small
abdomen - tying thread
collar - Ice Dub UV dark brown (turns a cool purplish brown)
thorax - glass bead red
underwing/legs - CDC dun brown
wing - deer hair
Part 1
Mash down barb, slide bead on
tie in rib, wrap halfway down bend and return to point above point
tie in some pheasant tail fibers
capture tips with rib and continue up the hook; helicopter end and cover with thread
dub collar; tie off thread
push bead back tight against collar and re-start thread
tie in CDC, leave butts long