The method by which fireflies produce light is perhaps the best known example of bioluminescence. When oxygen combines with calcium, adenosine triphosphate (ATP) and the chemical luciferin in the presence of luciferase, a bioluminescent enzyme, light is produced.

Why do fireflies glow only at night?

Fireflies mostly only glow at night because that's when the males are trying to get the attention of female fireflies, according to entomologist Dr. Sandy Smith.

Where does the light from a firefly come from?

Bioluminescent beetles

Fireflies produce light in special organs in their abdomens by combining a chemical called luciferin, enzymes called luciferases, oxygen and the fuel for cellular work, ATP. Entomologists think they control their flashing by regulating how much oxygen goes to their light-producing organs.