Illumination: The beetle sheds bright light in a 10-foot radius and dim light for an additional 10 feet.
A giant fire beetle is a nocturnal creature that takes its name from a pair of glowing glands that give off light. Miners and adventurers prize these creatures, for a giant fire beetle's glands continue to shed light for ld6 days after the beetle dies. Giant fire beetles are most commonly found underground and in dark forests.
It's not clear from this feature or description if the beetle shines this light 24/7, or has the ability to dim itself. Has this creature been in previous versions of D&D? Is it based on a real-life counterpart?