Don’t let the makeup companies find out. Lady glow-worms are setting an unattainable beauty standard by using bright light to show males how fertile they are. It’s a rare (in the animal world) example of females decorating themselves while their mates choose between them.
The European glow-worm, or Lampyris noctiluca, is a member of the firefly family in which the females do most of the glowing. Males are ordinary-looking beetles with brown wings. Females are much larger and don’t have wi