The larva or wingless grub-like female of a beetle from the families Phengodidae or Lampyridae that gives out a green light from its abdomen.
1604, William Alexander, The Alexandraean Tragedie, Act V, Scene 2, in The Monarchicke Tragedies, London: Ed. Blount, 1607,
Some things afarre doe like the Glow-worme shine,
That lookt to neere haue of that light no signe.
1819, William Wordsworth, “The Waggoner” Canto 1, in The Miscellaneous Poems of William Wordsworth, London: Longman, Hurst, Rees, Orme & Brown, 1820, p. 7,
Confiding Glow-worms, ’tis a night
Propitious to your earth-born light!
(Australia, New Zealand) A carnivorous gnat larva in the keroplatid genus Arachnocampa that spins threads to capture insects attracted by its glow.