I believe it was Gary Lafontane who started Antron use in flies with his caddis patterns. Caddis seem to ascend to the surface with gas bubbles which create a glowing halo around their form. Antron seems to replicate this. It also adds some flash due to the shape of it's fibers. I have photos of this effect in both fly and imitation, but the server won't let me upload them for some reason. I'll try later.