RAH, My bad, I saw bait wholesalers selling chartreuse or glow nightcrawlers with cool visibility studies in dark water where they really stand out. I assumed the glow capability of luminescent insects (fireflies) was incorporated into the worm, but I was wrong. I guess it is a chemical that is added to the worm, or their bedding and either it is ingested by the worms or just sticks to their slime layer and adds the coloring.
Probably someone knows more about this than me. Apparently you can buy the colorant and make your own. Lots of pictures on google if you are interested.
chartreuse crawlers
