Fear of the Dark

The firefly use of bioluminescence to attract mates or prey. It's capable of producing a "cold light" containing no ultraviolet rays, with a wavelength from 510 to 670 nanometers, pale yellowish or reddish green in color, with a lighting efficiency of 96%.

Bioluminescence is a very efficient process. 90 per cent of the firefly's energy is converted into light. By comparison, an incandescent electric bulb can convert only 10 percent of total energy into light, and the remainder is emitted as heat.

Light production in fireflies is due to a chemical reaction that occurs in specialized light-emitting organs, usually on the lower abdomen. The enzyme luciferase acts on luciferin in this organ to stimulate light emission. This reaction is of scientific interest. Genes coding for these substances have been inserted into many different organisms (Mice, silkworms, and potatoes). Luciferase is also used in forensics, and the enzyme has medical uses.

Tropical fireflies, particularly in Southeast Asia (Thailand and Malaysia), routinely synchronize their flashes among large groups, a startling example of spontaneous biological order. This phenomenon occurs through the night along river banks in the Malaysian jungles every day of the year. Current hypotheses about the causes of this behavior involve diet, social interaction, and altitude. In the United States, one of the most famous sightings of fireflies blinking in unison occurs near Elkmont, Tennessee in the Great Smoky Mountains during the second week of June.