This is my adaptation of the San Juan Worm.
It incorporates a weighted bead head and may in many circumstances not require additional weight to the tippet.
Hook: Kamasan B110 (Grubber) or similar. Size 16 to 12
Body: 2″ of wrapped elastic thread. Hot Pink. I purloined this from a girls bracelet bead kit.
Bead: 1/8 inch Tungsten Gold
Thread: 6 0 tan or similar.
Thorax: One strand braided sewing thread color 806
Start by threading the pink elastic thread through the bead:
Pass the hook, with the barb mashed down, through narrower hole in the the bead:
Start wrapping the 6 0 tan thread behind the bead back to the bend in the hook:
Tie in the sewing thread from the hook bend; make sure to keep the pink elastic thread on top of the hook shank:
Wrap the sewing thread forward to the bead; again ensuring that the pink elastic stays on top of the hook shank:
Whip finish the tying thread behind the bead; trim off the sewing thread and the fly tying thread:
Add a small drop of head cement to the body threads; trim the pink elastic 1/2 inch in front of the bead:
add a drop of red head cement to the cut end to prevent fraying:
Trim the rear elastic thread about 1 inch from the back of the bead; add a drop of clear head cement to the cut end. Use a dark brown permanent marker to detail the elastic with bands of color. Also use the marker pen to color the top of the thorax and top of the gold bead:
Finish of with a small application of clear head lacquer or epoxy to the thorax and bead; remember to keep the eye of the hook free of cement.
Feel free to experiment with other color combinations; below is a variant Damsel fly pattern using black and pale blue plastic beads instead of weighted tungsten.
I added some wings and some singed nylon eyes: (and also some Cul de Canard applied to assist floatation).