The Lampyridae are a family of insects in the beetle order Coleoptera. They are winged beetles, commonly called fireflies or lightning bugs for their conspicuous use of bioluminescence during twilight to attract mates or prey. Fireflies produce a “cold light”, with no infrared or ultraviolet frequencies. This chemically produced light from the lower abdomen may be yellow, green, or pale red, with wavelengths from 510 to 670 nanometers.About 2,000 species of fireflies are found in temperate and tropical climates. Many are in marshes or in wet, wooded areas where their larvae have abundant sources of food. Their larvae emit light and often are called “glowworms” in Eurasia and elsewhere. In the Americas, “glow worm” also refers to the related Phengodidae. In many species, both male and female fireflies have the ability to fly, but in some species, the females are flightless. Light production in fireflies is due to a type of chemical reaction called bioluminescence. This process occurs in specialized light-emitting organs, usually on a firefly’s lower abdomen. The enzyme luciferase acts on the luciferin, in the presence of magnesium ions, ATP, and oxygen to produce light. Gene coding for these substances has been inserted into many different organisms (see Luciferase – Applications). Firefly luciferase is used in forensics, and the enzyme has medical uses — in particular, for detecting the presence of ATP or magnesium. All fireflies glow as larvae. In lampyrid larvae, bioluminescence serves a function that is different from that served in adults. It appears to be a warning signal to predators, since many firefly larvae contain chemicals that are distasteful or toxic.