Lay a thread base from behind the eye back to just short of the hook point; that spot marks where the tail will be tied in.
Bind the 3/16" Red Dumbbell Eyes on top of the shank about one-third of the way back from the eye (the tyer ends up closer to halfway). On top means the fly rides hook point up; set this far back, the weight gives a sink with a lateral dart rather than a jig.
Take a small bunch of the belly colour Kreelex, wet it to flatten the waves, and trim the butts flush. Measure about a hook length, slightly longer, for the tail, then take loose wraps back to just short of the hook point, followed by secure wraps.
Bring the forward butts up to the front with a couple of wraps, open-wrap to the eye, then fold them back over the eyes and cinch the thread tight right in front of the eyes before working back. This adds bulk and taper and puts the belly colour underneath. Trim the folded strands at the halfway point of the tail.
Take a generous chunk of the back colour Kreelex, about the same width as the belly bunch, advance the thread in front of the eyes, lay it on top, two loose wraps then secure to the eye. Trim the butts flush and trim the tips to about the same length as the belly material.
Finish with clean thread wraps at the head and touch the wraps up with a marker so white thread disappears. Touch Zap-A-Gap on the head wraps and one drop in front of the eyes, then wet the fly down to check the profile and trim any strays.
Other versions
4 more in the app: Classic Recipe, Light, Gold, Purple.