Who's the brightest spark out there? It has to be the glow-worm

Havant Thicket, Hampshire The beetle's astonishingly efficient process means 98% of the energy linked to the chemical reaction is emitted as light

It was just before 10pm when I spotted the first vivid green spark in the understorey - a female common glow-worm. She had climbed a tall blade of grass and was advertising her availability to males on the wing, curling her abdomen to show off the bioluminescent rear segments to their best effect.

The ethereal illumination - which can also act as a warning - is generated within the glow-worm's light-producing organ, known as the lantern. A chemical reaction occurs between oxygen, the light-emitting compound luciferin, an energy-transporting molecule called adenosine triphosphate, and the enzyme luciferase.