Bead a size 16 Daiichi 1760 with a 2mm black tungsten bead and run the thread down to the bend and back. Tungsten matters on a bloodworm. These are bottom flies, and if you will not use tungsten then rig a split shot or swivel instead.
Tie small gold ultra wire in on the near side and bind it down to the bend.
Tie in red Buzzer Wrap by its very end with tight wraps, then run the thread back up. Going down and back like this has already built you all the body you need. Do not add a taper, because natural bloodworms do not have one.
Wrap the Buzzer Wrap forward up the shank to the bead in even turns and tie it off with a couple of wraps.
Rib the wire forward, evenly spaced, with no particular count in mind, then capture it, spin it off and go straight into a whip finish.
Coat the whole fly in superglue or UV resin. That coat is not optional on a soft-wrap body. It is what turns a two-fish fly into a season fly.
Fish it deep in the fall. As the weed dies back the bloodworms living in it get on the move and the trout key hard on them.