Firefly luciferin
Firefly luciferin (also known as beetle luciferin) is the luciferin, precursor of the light-emitting compound, used for the firefly (Lampyridae), railroad worm (Phengodidae), starworm (Rhagophthalmidae), and click-beetle (Pyrophorini) bioluminescent systems. It is the substrate of firefly luciferase (EC 1.13.12.7), which is responsible for the characteristic light emission of many firefly and other insect species in the visible spectra ranging from 530 until 630 nm.