Lay a thread base the length of the shank. Cut a strip of 2mm rootbeer foam about a gap-and-a-half wide and tie it in at the bend, leaving the long end pointing back over the bend.
Dub a thin golden-brown underbody forward to the 70% point to give the foam a warm glow and something to seat against.
Pull the foam strip forward over the top to form the segmented body and tie it down at the 70% mark; take a couple of cinch wraps to create a distinct segment. Add a set of knotted rubber legs at the tie-down point, one leg to each side.
Tie in a small bunch of rootbeer Krystal Flash as a short underwing, then lay a strip of 0.5mm tan cross-link foam flat over the top as the overwing, extending to about the end of the bend.
Add a second set of rubber legs at the front, splayed to the sides. Build a small foam head and, if desired, leave a stub of yellow foam standing up as a hi-vis indicator.
Whip finish under the wing and add a drop of cement. Keep the profile slender. The fly should look like a stonefly silhouette when viewed from below.