A reader from San Antonio, Texas wrote to us about worms with bioluminescence that he has been finding around his home. He hasn’t found the bioluminescent worms very often – just on a few evenings, and only during the winter months. When a worm exhibits bioluminescence, this means that its body is producing and emitting light though a chemical reaction – in other words, a bioluminescent worm is a worm that glows. So, in short, our reader is finding some sort of glowing worm. There are a number of so-called “glowworms” (also spelled “glow worms”), and of course all of these worms (which are actually not worms, but insect larvae) exhibit bioluminescence. Our reader was curious what kind of glowing worm he found, and it might seem obvious that he found some type of glowworm, but it’s a little more complicated than that. Below we’ll explain what glowworms are, and in so doing we’ll try to help our reader with his question about the bioluminescent worm he found.