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Any crawling, luminous insect that emits light either continuously or in prolonged glows rather than in the brief flashes characteristic of most fireflies. Glowworms include larvae and adult (often wingless) females of fireflies and certain other beetle species and larvae of certain gnat species. They are widely distributed. The great diversity in the size, number, location, and structure of the bioluminescent organs suggests that the light-producing ability of the various species evolved independently.
This entry comes from Encyclopædia Britannica Concise. For the full entry on glowworm, visit Britannica.com.