Thread Chartreuse or tan Danville flat waxed nylon
Materials
Eyes (weight) Lead dumbbell (1 pair)
Tail/claws Cream or ginger hackle tips, splayed (4 tips)
Flash Pearl flashabou (2 strands)
Body Tan rug yarn (Antron), tied cross-wise (5-6 short pieces)
Legs White round rubber, tips marked red (3 pairs)
How to tie it
Lash the lead dumbbell on top of the shank just behind the hook eye with figure-eights so the fly rides point-up.
At the bend, tie in four hackle tips splayed in pairs to each side as claws, with a couple strands of pearl Flashabou.
Cut 5-6 short lengths of tan Antron rug yarn and tie each across the shank with figure-eight wraps, cross-ways like a row of bow ties, packing them tightly forward to the eyes.
Tie a rubber leg in at each of three gaps between yarn segments as you go, one per side.
Whip finish at the head, then trim the yarn into a neat oval carapace, flat and wide. The segmented yarn body is what gives the Merkin its unmistakable crab footprint.
Trim legs to just past the body and touch the tips with red marker; cement the head.