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The Lampyridae are a family of Elateroidea beetles with more than 2,000 described species, many of which are bioluminescence. They are soft-bodied beetles commonly called fireflies, lightning bugs, or for their conspicuous production of light, mainly crepuscular, to attract mates. BugGuide: common names The type species is Lampyris noctiluca, the common glow-worm of Europe. Light production in the Lampyridae is thought to have originated as a Aposematism honest signal that the were distasteful. This ability to create light was then co-opted as a mating signal and, in a further development, adult female fireflies of the genus Photuris mimic the flash pattern of the Photinus beetle to trap their males as prey.
Fireflies are found in temperate and tropical climates. Many live in or in wet, wooded areas where their larvae have abundant sources of food. Although all fireflies nominally glow as larvae, only some species produce light in their adult stage, and the location of the light organ varies among species and between sexes of the same species. Fireflies have attracted human attention since classical antiquity; their presence has been taken to signify a wide variety of conditions in different cultures and is especially appreciated aesthetically in Japan, where parks are set aside for this specific purpose.
The larvae feed until the end of the summer. Most fireflies hibernate as larvae. Some do this by burrowing underground, while others find places on or under the bark of trees. They emerge in the spring. At least one species, Ellychnia corrusca, overwinters as an adult. The larvae of most species are specialized and feed on other larvae, terrestrial , and . Some are so specialized that they have grooved mandibles that deliver digestive fluids directly to their prey. The larval stage lasts from several weeks up to, in certain species, two or more years. The larvae for one to two and a half weeks and emerge as adults.
Adult diet varies among firefly species: some are predatory, while others feed on plant pollen or nectar. Some adults, like the European glow-worm, have no mouth, emerging only to mate and lay eggs before dying. In most species, adults live for a few weeks in summer.
Fireflies vary widely in their general appearance, with differences in color, shape, size, and features such as antennae. Adults differ in size depending on the species, with the largest up to long. Many species have non-flying . These can often be distinguished from the larvae only because the adult females have arthropod eye, unlike the simple eyes of larvae, though the females have much smaller (and often highly regressed) eyes than those of their males. The most commonly known fireflies are Nocturnality, although numerous species are diurnality and usually not luminescent; however, some species that remain in shadowy areas may produce light.
Most fireflies are distasteful to vertebrate predators, as they contain the steroid pyrones , similar to the cardiotonic Bufanolide found in some poisonous toads. All fireflies glow as larvae, where bioluminescence is an Aposematism warning signal to .
Adults emit light primarily for mate selection. Early larval bioluminescence was adopted in the phylogeny of adult fireflies, and was repeatedly gained and lost before becoming fixed and retained as a mechanism of sexual communication in many species. Adult lampyrids have a variety of ways to communicate with mates in courtships: steady glows, flashing, and the use of chemical signals unrelated to photic systems. Chemical signals, or pheromones, are the ancestral form of sexual communication; this pre-dates the evolution of flash signaling in the lineage, and is retained today in diurnally-active species. Some species, especially lightning bugs of the genera Photinus, Photuris, and Pyractomena, are distinguished by the unique courtship flash patterns emitted by flying males in search of females. In general, females of the genus Photinus do not fly, but do give a flash response to males of their own species. Signals, whether photic or chemical, allow fireflies to identify mates of their own species. Flash signaling characteristics include differences in duration, timing, color, number and rate of repetitions, height of flight, and direction of flight (e.g. climbing or diving) and vary interspecifically and geographically. When flash signals are not sufficiently distinguished between species in a population, sexual selection encourages divergence of signaling patterns.
Synchronization of flashing occurs in several species; it is explained as phase synchronization and spontaneous order. Tropical fireflies routinely synchronise their flashes among large groups, particularly in Southeast Asia. At night along river banks in the Malaysian jungles, fireflies synchronize their light emissions precisely. Hypotheses for the causes of this behavior involve diet, social interaction, and altitude. In the Philippines, thousands of fireflies can be seen all year-round in the town of Donsol. In the United States, one of the most famous sightings of fireflies blinking in unison occurs annually near Elkmont, Tennessee, in the Great Smoky Mountains during the first weeks of June. Synchronous Fireflies – Great Smoky Mountains National Park. Nps.gov (3 June 2013). Retrieved on 22 June 2013. Congaree National Park in South Carolina is another host to this phenomenon.Cross, Robert (23 May 2004) " Tree huggin'". Chicago Tribune.
Female "femme fatale" Photuris fireflies mimic the photic signaling patterns of the smaller Photinus, attracting males to what appears to be a suitable mate, then eating them. This provides the females with a supply of the toxic defensive lucibufagin chemicals.
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 inhabit primarily shadowy places, such as beneath tall plants or trees, are luminescent. One such genus is Lucidota.
Non-bioluminescent fireflies use pheromones to signal mates. Some basal groups lack bioluminescence and use chemical signaling instead. Phosphaenus hemipterus has photic organs, yet is a diurnal firefly and displays large antennae and small eyes. These traits suggest that pheromones are used for sexual selection, while photic organs are used for warning signals. In controlled experiments, males coming from downwind arrived at females first, indicating that males travel upwind along a pheromone plume. Males can find females without the use of visual cues, so sexual communication in P. hemipterus appears to be mediated entirely by pheromones.
Fireflies face threats including habitat loss and degradation, light pollution, pesticide use, poor water quality, invasive species, over-collection, and climate change. Firefly tourism, a quickly growing sector of the travel and tourism industry, has also been identified as a potential threat to fireflies and their habitats when not managed appropriately. Like many other organisms, fireflies are directly affected by land-use change (e.g., loss of habitat area and connectivity), which is identified as the main driver of biodiversity changes in terrestrial ecosystems. Pesticides, including and , have also been indicated as a likely cause of firefly decline.Potter, Daniel A. See "How You Can Help", FireFly.org, citing (1) "Understanding Halofenozide (Mach 2) and Imidacloprid (Merit) Soil Insecticides," International SportsTurf Institute, Incorporated, Turfax, Vol. 6, No. 1 (Jan-Feb 1998) and (2) "Relative Toxicities of Chemicals to the Earthworm Eisenia foetida," by Brian L. Roberts and H. Wyman Dorough. Article first published online: 20 October 2009. Environmental Toxicology and Chemistry, Vol. 3, No. 1 (Jan. 1984), pp. 67–78. These chemicals can not only harm fireflies directly but also potentially reduce prey populations and degrade habitat. Light pollution is an especially concerning threat to fireflies. Since the majority of firefly species use bioluminescent courtship signals, they are also sensitive to environmental levels of light and consequently to light pollution. A growing number of studies investigating the effects of artificial light at night on fireflies has shown that light pollution can disrupt fireflies' courtship signals and even interfere with larval dispersal. Researchers agree that protecting and enhancing firefly habitat is necessary to conserve their populations. Recommendations include reducing or limiting artificial light at night, restoring habitats where threatened species occur, and eliminating unnecessary pesticide use, among many others.
In Italy, the firefly (Italian language: lucciola) appears in Canto XXVI of Dante's Inferno, written in the 14th century:
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