The firefly is the insect that uses bioluminescence in its abdomen to attract mates. Fireflies are beetles in the family Lampyridae, and their familiar flashes are produced by specialized light organs called photophores.
The light comes from a chemical reaction involving luciferin, luciferase, oxygen, ATP, and magnesium ions. It is often described as “cold light” because very little energy is lost as heat. Depending on the species, the glow may appear yellow, green, or pale red.
Firefly courtship signals are highly specific. Flashes can differ in timing, duration, color, repetition rate, and flight pattern, helping males and females recognize members of their own species. In many species, flying males signal first and females answer from vegetation or the ground.
Not every glowing insect is a firefly, and “glowworm” can refer to fireflies or unrelated luminous larvae. Firefly larvae also glow, probably as a warning that they taste unpleasant to predators. Some Photuris females exploit courtship signals by imitating another species and eating the males they attract.