glowworm
noun
glow·worm ˈglō-ˌwərm 
: any of various luminous insect larvae or adults with wings rudimentary or lacking
especially : a larva or wingless female of a firefly (family Lampyridae) that emits light from the abdomen
Did you know?
This is any crawling, luminous insect that emits light either continuously, or in prolonged glows, rather than in the brief flashes that are characteristic of most fireflies. Glowworms include larvae and adult (often wingless) females of fireflies and certain other beetle species, as well as the larvae of certain gnat species. They are widely distributed. There is great diversity in the size, number, location, and structure of the bioluminescent organs of glowworms.
Example Sentences
Recent Examples on the Web Picture everyone on the tour turning off their flashlights, then your eyes adjust to witness these glowworms lighting up the rock faces. 
Brent Conklin | Bconklin@al.com, al, 31 May 2020 Spend a day black-water tubing through caverns lit by thousands of tiny glowworms, traveling to the cave entrance via zip line and finishing the adventure on a series of natural rock slides. National Geographic, 20 Sep. 2019 As if huge, ancient subterranean caverns weren’t enough, many of them are covered in twinkling blue glowworms that shine like stars above you. Liz Carlson, Outside Online, 24 June 2019 Go black-water rafting in a cave lit by glowworms, and take a wet ride along natural rock water slides. National Geographic, 17 June 2019 Your Nerves While Blackwater Rafting in a Glowworm CaveThe glowworm caves are one of New Zealand’s most unique features. Liz Carlson, Outside Online, 24 June 2019 Spend a day black-water tubing through caverns lit by thousands of tiny glowworms, traveling to the cave entrance via zipline and finishing the adventure on a series of natural rock slides. National Geographic, 17 June 2019 Though some of the most familiar examples of light from living organisms are terrestrial — think of fireflies, glowworms and foxfire — the bulk of evolutionary events involving bioluminescence took place in the ocean. Quanta Magazine, 1 Dec. 2016 The prey is drawn in by the glowworm's bioluminescent abilities, similar to a porch light that attracts insects. Liz Langley, National Geographic, 2 July 2016 See More
Brent Conklin | Bconklin@al.com, al, 31 May 2020 Spend a day black-water tubing through caverns lit by thousands of tiny glowworms, traveling to the cave entrance via zip line and finishing the adventure on a series of natural rock slides. National Geographic, 20 Sep. 2019 As if huge, ancient subterranean caverns weren’t enough, many of them are covered in twinkling blue glowworms that shine like stars above you. Liz Carlson, Outside Online, 24 June 2019 Go black-water rafting in a cave lit by glowworms, and take a wet ride along natural rock water slides. National Geographic, 17 June 2019 Your Nerves While Blackwater Rafting in a Glowworm CaveThe glowworm caves are one of New Zealand’s most unique features. Liz Carlson, Outside Online, 24 June 2019 Spend a day black-water tubing through caverns lit by thousands of tiny glowworms, traveling to the cave entrance via zipline and finishing the adventure on a series of natural rock slides. National Geographic, 17 June 2019 Though some of the most familiar examples of light from living organisms are terrestrial — think of fireflies, glowworms and foxfire — the bulk of evolutionary events involving bioluminescence took place in the ocean. Quanta Magazine, 1 Dec. 2016 The prey is drawn in by the glowworm's bioluminescent abilities, similar to a porch light that attracts insects. Liz Langley, National Geographic, 2 July 2016 See More Word History
Etymology
Middle English
First Known Use
14th century, in the meaning defined above
Kids Definition
glowworm
noun
glow·worm ˈglō-ˌwərm
: an insect or insect larva that gives off light