any of some 2,000 species of beetles (insect order Coleoptera) found in most tropical and temperate regions that have special light-producing organs on the underside of the abdomen. Most fireflies are nocturnal, although some species are diurnal. They are soft-bodied beetles that range from 5 to 25 mm (up to 1 inch) in length. The flattened, dark brown or black body is often marked with orange or yellow. Some adult fireflies do not eat, whereas many feed on pollen and nectar. In a few species females are predatory on males of other firefly species. Both sexes are usually winged and luminous (bioluminescence), although in some species only one sex has the light-producing organ. Females lacking wings and resembling the long, flat larvae are commonly referred to as glowworms. The larvae are sometimes luminescent before they hatch. Larvae live on the ground and feed on snails and slugs by injecting a fluid into their prey and then withdrawing the partly digested matter through hollow mouthparts. The common glowworm (Lampyris noctiluca) is a member of this family (see glowworm).