Start 140 denier black thread on a standard-length dry fly hook and lay a base back to the start of the bend. The heavier thread makes the foam much easier to handle.
Wax the thread and spin about a two-inch noodle of dark synthetic sparkle dubbing for the Underbody. Wrap it almost all the way to the eye, then take the thread back so it hangs about a third of the way back from the eye.
Cut a rough egg-shaped oval of 2mm black foam about a hook gap wide and one and a half times the body length. Catch it in at the hanging thread with the rear section just past the bend; the front section becomes the head.
Lay a wide band of not-very-tight wraps across the foam so you have a flat, banded tie-down area.
Fold a length of black rubber leg over, pull out plenty of slack thread, and take five or six very loose wraps on that band, positioning the legs off both sides. Only then add one or two tighter wraps.
Trim the legs to size, cutting the front pair a little shorter than the back so it does not read as a panfish spider.
Tie a small piece of bright 2mm foam in on top for the Indicator, letting it flare up under several wraps, then trim it with the front a little shorter than the back.
Strip a few barbs short at the base of a grizzly hackle dyed brown, green or olive, and catch it in on the near side of the indicator post, small end pointing forward, with three wraps.
Wrap the hackle parachute-style around the post for two or three turns, over the legs but under the indicator.
Tie the hackle off by zigzagging the hanging thread through the barbs two or three turns until you come out underneath, then run the thread up to the eye and whip finish.
Trim the hackle tip and clip the foam head shorter. Beetle heads are not big.