The glow-worms, named for their famed bioluminescence.  Three species have been found in Britain although one (Lamprohiza splendidula (L.)) is known only from two specimens collected in 1884. All the British species of this group are strongly sexually dimorphic, with a small, winged male (c. 5mm) and a much larger larviform female (to 16mm).

By far the most widespread (though thought to be declining) is Lampyris noctiluca L., the glow-worm.  Females are strongly bioluminescent; males less so and larvae barely.  Males have full elytra and larvae feed on snails.

The lesser glow-worm Phosphaenus hemipterus (Goeze) has been recorded from a handful of sites across southern England but only one extant colony is known, near Burlesdon in Hampshire.  Both sexes are flightless and only weakly bioluminescent: the female (13mm) is wingless while the 10mm male has abbreviated wing-cases and looks rather like a Staphylinid.