Chamois, leather, or rabbit strip Tan/gray chamois leather or rabbit strip (1 short strip (tail))
Deer or elk body hair Natural tan/gray deer or elk body hair (several clumps (spun body))
Rubber legs or mono Natural (whiskers, optional) (few)
How to tie it
Start thread at the bend and tie in a thin chamois or rabbit-strip tail about one shank length long, lying flat.
Cut, clean, and stack a clump of deer body hair, then spin it around the shank and pack it back tight; repeat clump by clump, packing hard, forward to the eye to build a dense body.
Whip finish at the eye and remove the fly from the vise.
Trim the spun deer hair to a rounded mouse shape, flat on the bottom and tapered to a pointed nose, leaving it slightly larger at the rear.
Optionally poke a couple of mono or rubber whiskers into the nose and add small ears.