Why do fireflies glow?


Why do fireflies glow?
—Insect Identifier

Fireflies light up to attract and respond to mates (and, in some cases, to deter predators). There are more than 150 species of fireflies in North America. None are actually flies—they’re beetles—and not all have the ability to self-illuminate. The species that do can produce their own unique patterns of flashes. The patterns vary by colour, length, the number of flashes or flickers, and the time interval between flashes. The bioluminescent energy that the beetles generate comes from a reaction within the light-producing organs in their lower abdomens, involving oxygen, a chemical called luciferin, and an enzyme called luciferase.

While some fireflies don’t eat during their adult lives (one to three weeks), firefly larvae are carnivorous. They feed off of worms, snails, slugs, and other insect larvae. And certain adult species, for example, Photuris, prey on other fireflies. The female mimics the flash of a smaller, similar firefly species to lure a male; when he approaches, she attacks and eats him. Gah! Brutal bait and switch.