|Adult Photuris lucicrescens firefly|
Adult Photuris lucicrescens firefly
Lampyridae is a family in the beetle order Coleoptera, members of which are commonly called fireflies, lightning bugs or (ambiguously) "glow worms" due to their conspicuous nocturnal (or, more accurately, crepuscular) use of bioluminescence to attract mates or prey. Fireflies are capable of producing a "cold light" containing no ultraviolet or infrared rays, with a wavelength from 510 to 670 nanometers, pale reddish, yellowish or green in colour, with a lighting efficiency of up to 96%.
There are more than 2000 species of firefly found in temperate and tropical environments around the world. Many species can be found in marshes or in wet, wooded areas where their larvae have abundant sources of food.
Fireflies tend to be brown and soft-bodied, often with the elytra more leathery than in other beetles. Though the females of some species are similar in appearance to males, larviform females are found in many other firefly species. These females can often be distinguished from the larvae only because they have compound eyes.The most commonly known fireflies are nocturnal, though there are numerous species that are diurnal. Most diurnal species are non-luminescent, though some species that remain in shadowy areas can produce light.
A few days after mating, a female lays her fertilized eggs on or just below the surface of the ground. The eggs hatch 3-4 weeks later and the larva feed until the end of the summer. The larvae are commonly called glowworms, not to be confused with the distinct beetle family Phengodidae or fly genus Arachnocampa. Lampyrid larvae have simple eyes. The term glowworm is also used for both adults and larvae of species such as Lampyris noctiluca, the common European glowworm, in which only the non-flying adult females glow brightly and the flying males glow only very weakly and intermittently. Fireflies overwinter (some species for several years) during the larval stage. Some do this by burrowing underground, while others find places on or under the bark of trees. They emerge in the spring. After several weeks of feeding, they pupate for 1 to 2.5 weeks and emerge as adults. The larvae of most species are specialized predators and feed on other larvae, terrestrial snails, and slugs. Some are so specialized that they have grooved mandibles which deliver digestive fluids directly to their prey. The diet of adults is variable. It has been reported that some are predatory and some feed on plant pollen or nectar.
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 (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 occurs near Elkmont, Tennessee in the Great Smoky Mountains during the second week of June 2005. Congaree National Park in South Carolina is 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.
Firefly systematics, like with many insects, are in a constant state of flux, as new species continue to be discovered. The 5 subfamilies listed above are the most commonly accepted ones, though others such as the Amydetinae and Psilocladinae have been proposed. This was mainly done in an attempt to revise the Lampyrinae, which by and by had become something of a "wastebin taxon" to hold incertae sedis species and genera of fireflies. Other changes are occasionally proposed, such as merging the Ototetrinae into the Luciolinae, but the arrangement used here appears to be the most frequently-seen and stable layout, at least for the time being.
Fireflies and humans
Fireflies were a part of ancient Mayan mythology, often being associated with the stars. Further, they were associated with cigar smoking and may have had at least one representative in the pantheon of Mayan gods (Lopes 2004).
In East Asia, the ancient Chinese sometimes captured fireflies in transparent or semi-transparent containers and used them as (short-term) lanterns, and some species of the genus Luciola (hotaru, 蛍) rival the famous sakura cherry blossoms as regards their significance in Japanese culture and folklore.
The Pennsylvania Firefly (Photuris pennsylvanica) is the state insect of Pennsylvania, and the Common Eastern Firefly (Photuris pyralis) one of the state insects of Tennessee. At one point, Indiana seriously considered making the State's insect a firefly, but the legislature never put the measure to a vote.
The spectacular synchronized flashing by Pteroptyx and other Luciolinae fireflies has potential economic significance. Notably on the Selangor River at Kampong Kuantan (Malaysia), it has become a major attraction for tourists which create considerable revenue.
|Wikimedia Commons has media related to Lampyridae.|
- Lampyridae (TSN 113835). Integrated Taxonomic Information System. Retrieved on 30 April 2006.
- Branham, M. A., and J. W. Wenzel. 2003. The origin of photic behavior and the evolution of sexual communication in fireflies (Coleoptera: Lampyridae). Cladistics 19: 1-22.
- Lopes, Luís. 2004. Some notes on fireflies. Mesoweb. http://www.mesoweb.com/features/lopes/Fireflies.pdf
- Stous, Hollend. 1997. A review of predation in Photuris, and its effects on the evolution of flash signaling in other New World fireflies. http://www.colostate.edu/Depts/Entomology/courses/en507/papers_1997/stous.html
- http://www.fireflies.tk . A site about the Firefly meeting 2007 in Portugal and information on fireflies in general.