The fireflies or lightning bugs (Lampyridae) are a speciose beetle family of the temperate to tropical regions with around 2000 species worldwide, thereof three in Germany. They are mainly found in wet and wooded areas. Many species exhibit a marked sexual dimorphism with winged males and larviform females. Besides a number of diurnal species there is a large number of nocturnal species. The latter are known for their conspicuous use of bioluminescence to attract mates or prey. They are capable of producing "cold light" from oxidation of luciferin (a benzothiazol derivative) in the presence of the enzyme luciferase, ATP and magnesium ions. The light may be green, yellow or pale red in color, and has a wavelength from 510 to 670 nm. Bioluminescence is a form of chemiluminescence, where energy is released by a chemical reaction in the form of light emission. Less than 10% of the energy is released as heat.