From the hook eye to the back make an even base of thread and tie a Thin Skin strip by its tip, as seen on the picture.
Tie the lead wire strips at each side of the hook, so they get to the Thin Skin. The two tips of this underbody must be square-shaped so that the stonefly has correct shape when finished.
Change the thread for a thicker one (white) and cover the lead wire evenly, cementing with cyanocrilate. Then, use the fine thread again.
Start wrapping the Thin Skin over the body without going to the back. After 2 or 3 turns, tie one tail with the Thin Skin, the one closer to us. And with the same turn but at the other side tie the other tail, keeping the quills at the side.
Finish covering the abdomen getting the Thin Skin turns together to make the segments of the stonefly. Cover the thorax as well and tie the Thin Skin firmly, trimming the remnants.
Make the first section of the thorax with some dubbing, tying towards the back and then back to the front. Two marabou –like fibers make the legs. The picture shows a wing case burnt with a special burner, ready to be tied at the dorsal section.
Here is the first tied wing case and a new section of the thorax with its legs placed, and ready for the second wing case.
As done before, place the second wing case, another dubbing section, the third pair of legs and the pronotum that is shaped like a wing case but with a rounded silhouette. Lower the pronotum covering the third section of the thorax and tie a strip of Thin Skin that will make the head together with the other two, which are tied on the lower side so that when the head is lowered these do not fold.
Some more dubbing makes the head bulkier. Then, we lower the Thin Skin tying firmly with five turns, right where we tied the pronotum. We just need to color the back of the fly matching the real insects, with permanent markers. Our Stonebou is now ready to fish.