Firefly (Lightning Bug)

Flashing above the lawn and in the trees in the early summer evenings, the firefly engages in its mating rituals, blinking on and off in a pattern that's unique to one of the many sub-species.

These insects — actually small beetles — go through a complete metamorphosis. The adults look nothing like the larvae.
The eating patterns between young and old are very different too: Larvae feed on snails, slugs, earthworms and insect larvae; adult fireflies — if they eat at all — feed on nectar and pollen.
Glowworms are cousins of fireflies but lack wings.