When do fireflies glow?

Answer 1

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. Genes coding for these substances have been inserted into many different organisms (see Luciferase - Applications). Luciferase is also used in forensics, and the enzyme has medical uses. For adult beetles, it is primarily used to locate other individuals of the same species for reproduction. Many species, especially in the genus Photinus, are distinguished by the unique courtship flash patterns emitted by flying males in search of females. Photinus females generally do not fly, but give a flash response to males of their own species. Bioluminescence is a very efficient process. Some 90% of the energy a firefly uses to create light is actually converted into visible light. By comparison, an incandescent electric bulb can convert only 10 percent of total energy used into visible light, and the remainder is emitted as heat. 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 occurred near Elkmont, Tennessee in the Great Smoky Mountains during the second week of June 2005. Congaree National Park in South Carolina is another host to the phenomenon. Female Photuris fireflies are known for mimicking the mating flashes of other fireflies for the sole purpose of predation. Target males are attracted to what appears to be a suitable mate, and are then eaten. For this reason the Photuris female is sometimes referred to as "femme fatale". Many fireflies do not produce light. Usually these species are diurnal, or day-flying, such as those in the genus Ellychnia. A few diurnal fireflies that primarily inhabit shadowy places, such as beneath tall plants or trees, are luminescent. One such genus is Lucidota. All fireflies glow as larvae. Bioluminescence serves a different function in lampyrid larvae than it does in adults. It appears to be a warning signal to predators, since many firefly larvae contain chemicals that are distasteful or toxic.