Adult lightning bugs usually eat other either insects, pollen or nectar, although some species, like the European glow-worm, have no mouth and are unable to eat at all. Larval lightning bugs are predators, eating worms, slugs, snails and small insects.
Many species of lightning bug are highly specialized for their prey. For example, adults in the genus Photuris eat other lightning bugs and imitate the mating signals of other species to catch them. Their prey is consumed by pouncing and biting. Other lightning bugs, especially the larval forms, prey upon soft-bodied invertebrates by injecting them with digestive fluid and sucking up their insides.