Slide a slotted tungsten bead onto the jig hook and mount it; add a few turns of lead wire behind the bead for extra weight to reach the larva zone quickly.
Start thread and lay a short butt of pearlescent tinsel at the bend.
Tie in a thin strip of chamois and wrap it forward, twisting slightly, to form a tapered segmented body over the rear two-thirds.
Counter-rib with fine wire or iridescent tinsel for segmentation and durability, then tie off.
Wind a peacock-herl thorax (or a sparse soft-hackle hen collar) up behind the bead.