Increased surface area. Only male glowworms metamorphose into adult forms and they use their feathery antennae to track females down by their pheromones. Increased antenna surface area helps them pick up those pheromones.

A threadbare merkin

I'm failing to see whatever it is you see, though I clicked through to the full size picture before looking at the thumbnail, so my view of the thumbnail was influenced by having seen the full size picture

As I said in another reply, two words... threadbare merkin.

I opened expecting something else, not going to lie. But it's a nice little bug.

Oh good it’s not just me. I was worried I would have to bonk myself.

Anyways…bonk

Might not be a live specimen

Here's one I photographed a year ago

He's gay