The Lampyridae are a family of elateroid beetles with more than 2,000 described species, many of which are light-emitting. They are soft-bodied beetles commonly called fireflies, lightning bugs, or glowworms for their conspicuous production of light, mainly during twilight, to attract mates. Light production in the Lampyridae is thought to have originated as an honest warning signal that the larvae were distasteful; this was co-opted as a mating signal in the adults. In a further development, female fireflies of the genus Photuris mimic the flash pattern of Photinus species to trap their males as prey.

Insect mandibles are a pair of appendages near the insect's mouth, and the most anterior of the three pairs of oral appendages. Their function is typically to grasp, crush, or cut the insect's food, or to defend against predators or rivals. Insect mandibles, which appear to be evolutionarily derived from legs, move in the horizontal plane unlike those of vertebrates, which appear to be derived from gill arches and move vertically.