A glowworm or firefly larva that produces bioluminescent light; any bioluminescent larval insect.
From 'glare' (shine/brightness) + 'worm' (larval insect). The compound name literally describes a worm that creates a glare or glow.
Firefly larvae are absolute light-producing factories—some can glow without moving, making them look like tiny floating coals, which is exactly why calling them glareworms makes perfect sense.
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