Start the brown 6/0 Nano Silk just behind the eye of the Ahrex FW 531, trim the tag, and work the thread a little way down the shank.
Cut a notch in the end of a strip of 1.5 MM Razor Foam to give a clean tie-in point, start the thread right at the point of the notch and work the wraps back down the shank.
Overhand-wrap the foam forward tightly along the shank and catch it on top with a few wraps; trim the excess and cover the butt with thread.
Wing: take about half a pencil width of bleached elk hair, pull out the underfluff, stack it to align the tips, and measure it against the fly.
Secure the elk hair with a couple of loose wraps that tighten as you go, working back onto the hair, then work the thread forward again.
Fold the butt ends back, take the thread under the eye a little and then back over the top; trim the top section flush, leaving just enough stub to form the head, and clean up the stragglers.
Legs: catch one MFC Centipede Leg in the middle on the near side and a second on the far side, positioning them where you want them to sit.
Hackle: tie the stem of the Whiting Farms High & Dry brown hackle in along the side and palmer it forward in close touching wraps until the midsection is full; secure with a few thread wraps and trim the feather.
Whip finish behind the eye, trim the thread, and trim the legs back to length.