Other forms: lightning bugs
A lightning bug is a flying insect that flashes a glowing light at night. Many people call lightning bugs "fireflies."
Lightning bugs look like ordinary small, winged beetles in the daylight, although they're mainly nocturnal, active primarily at night. The larvae of lightning bugs glow as well, and they're often called "glow worms." A chemical reaction in the lightning bug's abdomen is what allows them to light up — biologically, this is supposed to be a warning to predators, although it also acts as an invitation to kids to catch the glowing bugs.