Kelly devised this fly in the late 70’s for the hexagenia hatch (hence the name); change colors to suit your supersized mayfly hatch. Original had bucktail underbody, deer hair used here; your choice.
clean, stack (good luck with this), measure (hook shank) a good clump of calftail
two soft loops, then really lean on it wrapping back (don’t go in front of the initial wraps or all is lost); no place for wimpy thread here (UTC is the bomb), you don’t want a spun calftail wing
trim the butts, brush a little Sally and smooth with thread wraps
push the hair up and back, creasing it with your thumbnail; make a thread dam in front with a few firm wraps
flip it back over; clean, stack, measure (hook shank) some moose mane, tie in and wrap forward, creating smooth intersection with wing butts
invert again, pull deer hair forward keeping it on the underside, although it looks like the topside (confusing) and tie off at 70% mark
trim butts and return to the upright position (last time, promise)
clean, stack, measure (a bit past the bend) a clump of deer hair
tie in, keep the hair on top then continue wraps back towards the tail segmenting all the way, give a firm pull at the tail to flare the tips; return to the front with crossing wraps, trim butts
