About Phosphaenus hemipterus (Geoffroy, 1762)
This species of beetle, Phosphaenus hemipterus, has different body lengths for the two sexes: males measure 6–8 millimetres (0.24–0.31 in), while females reach 10 mm (0.39 in). Its body is dark brown with a reddish tinge. Females of this species are neotenic. Males have greatly shortened wing covers, and unlike males of most other firefly species, they closely resemble females of Phosphaenus hemipterus. Males also have reduced membranous wings, which makes them similar in appearance to flightless females. Phosphaenus hemipterus larvae are similar in appearance to adult females of the species, or to the larvae of the related Lampyris noctiluca. They differ from these by being smaller and more slender in build, and by lacking a bilateral series of pale dots on the abdomen. The species' light organ is formed by a pair of light spots located ventrally on the eighth abdominal segment.
