Fireflies!

• Not all firefly species are bioluminescent as adults, but of the species that are, one or both sexes use a species specific flash pattern to attract a member of the opposite sex. These bioluminescent signals can take the form of anything from a continuous glow, to discrete single flashes, to"flash-trains" composed of multi-pulsed flashes
• Fireflies are actually beetles!
• Fireflies are not really "flies" as entomologists know them, but are beetles in the family Lampyridae. "Flies" have one pair of wings (like houseflies) while all other winged insects have two pairs of wings, or, four wings altogether. In general, when the common names of insects contain the word "fly" as part of a one word common name such as firefly, dragonfly or scorpionfly, the insects are not true flies and belongs to another order of insects. When the word "fly" is hyphenated or follows the first word of an insect common name, it is most likely a true fly (and by definition, has only two wings.)