Fireflies produce light by mixing a chemical called luciferin, oxygen, and a helper enzyme called luciferase.

Think of it like a natural glow stick. Inside a firefly's belly, a chemical called luciferin reacts with oxygen. A helper protein called luciferase speeds up this reaction. This process releases energy as a soft, colorful glow. It all happens inside special light-making organs in the beetle's abdomen. Because the reaction does not need high energy, it is extremely efficient and safe.