A beetle larva or wingless female beetle that produces light through bioluminescence, commonly seen glowing in grass at night.
Compound of 'glow' (Old English glōwan, to shine) and 'worm' (Old English wyrm, a general term for creeping creatures). The term dates back several centuries and is particularly common in British English.
Glowworms are actually female fireflies or related beetles that never develop wings—they stay in their larval or neotenic form and glow to attract mates, while the males zip around looking for their light signals.
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