Free Fireflies

[Francisca Noggles]

Fireflies (also called lightning bugs) are beetles. Most of their lifecycle is spent in the larval stage (1-2 years), where they feed on snails, worms, and smaller insects in the leaf litter on the forest floor. Once they mature into the adult form, they only live for about 3-4 weeks and many do not feed.

Firefly flash patterns are part of their mating display. Each species has a characteristic pattern that helps male and female individuals recognize and find each other. Most species produce a greenish-yellow light, but others have more of a blue or white light. Males typically flash while they are flying, and females, which are usually stationary, flash in response.

The production of light by living organisms is called bioluminescence. Fireflies are a good example of an organism that produces light, but there are others as well, such as certain species of fungus, fish, shrimp, jellyfish, plankton, glowworm beetles, and gnats. Bioluminescence involves highly efficient chemical reactions that result in the release of light with little or no emission of heat. Fireflies combine the chemical luciferin and oxygen with the enzyme luciferase in their lanterns (part of their abdomens) to make light. The light produced is referred to as a "cold" light, with nearly 100% of the energy given off as light. In contrast, the energy produced by an incandescent light bulb is approximately 10% light and 90% heat.

Synchronous fireflies (Photinus carolinus) are one of at least 19 species of fireflies that live in Great Smoky Mountains National Park. They are one of only a couple species in North America whose individuals are known to synchronize their flashing light patterns.

Scientists studying the synchronous firefly have determined that the males flash in unison as a way for the female to be certain she is responding to one of her kind. There are other firefly species flashing at night, and some of them are predatory, so she must be able to recognize males of her species.

The flash pattern of Photinus carolinus is a series of 5-8 flashes, followed by a pause of about 8 seconds, and then this pattern is repeated. Initially the flashing appears random, but the period of darkness is synchronized. As more males start joining in, the flashing will also begin to synchronize and entire sections of the forest will be pulsating with light.

The mating season of Photinus carolinus lasts for approximately 2-3 weeks each year. The dates that they begin to display varies from year to year based on temperature and soil moisture. We use daily temperatures and predicted temperatures to set the dates of the public viewing event, but any natural phenomenon is highly variable and difficult to predict exactly.

As the season begins, a few insects start flashing, then more join the display as the days pass. They reach a peak and then the numbers gradually decline each day until the mating season is over. Since 1993, which is when dates were first recorded, this peak date has occurred at various times from the third week of May to the third week in June.

Amydetinae[1]
Cheguevariinae[2]
Chespiritoinae[3]
Cyphonocerinae
Lamprohizinae[1]
Lampyrinae
Luciolinae
Ototretinae
Photurinae
Psilocladinae[1]
Pterotinae[1]

The Lampyridae are a family of elateroid beetles with more than 2,000 described species, many of which are light-emitting. They are soft-bodied beetles commonly called fireflies, lightning bugs, or glowworms for their conspicuous production of light, mainly during twilight, to attract mates.[5] Light production in the Lampyridae is thought to have originated as a warning signal that the larvae 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 in order to trap their males as prey.

Fireflies are found in temperate and tropical climates. Many live in marshes or in wet, wooded areas where their larvae have abundant sources of food. While all known fireflies 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.

Fireflies are beetles and in many aspects resemble other beetles at all stages of their life cycle, undergoing complete metamorphosis.[6] A few days after mating, a female lays her fertilized eggs on or just below the surface of the ground. The eggs hatch three to four weeks later.[7] In certain firefly species with aquatic larvae, such as Aquatica leii, the female oviposits on emergent portions of aquatic plants, and the larvae descend into the water after hatching.[8]

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.[9] 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 that deliver digestive fluids directly to their prey. The larval stage lasts from several weeks up to, in certain species, two or more years.[10] The larvae pupate for one to two and a half weeks and emerge as adults.[7]

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.[7][11]

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 25 mm (1 in) long. Many species have non-flying larviform females. These can often be distinguished from the larvae only because the adult females have compound eyes, unlike the simple eyes of larvae, though the females have much smaller (and often highly regressed) eyes than those of their males.[12] The most commonly known fireflies are nocturnal, although numerous species are diurnal and usually not luminescent; however, some species that remain in shadowy areas may produce light.[6]

Most fireflies are distasteful to vertebrate predators, as they contain the steroid pyrones lucibufagins, similar to the cardiotonic bufadienolides found in some poisonous toads.[13] All fireflies glow as larvae, where bioluminescence is an honest aposematic warning signal to predators.[14][15][16]

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.[14][21] 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.[22] 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.[14][23] 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.[24][16] When flash signals are not sufficiently distinguished between species in a population, sexual selection encourages divergence of signaling patterns.[24]

Synchronization of flashing occurs in several species; it is explained as phase synchronization and spontaneous order.[25] 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. Current hypotheses about 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.[26] Congaree National Park in South Carolina is another host to this phenomenon.[27]

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.[14] This provides the females with a supply of the toxic defensive lucibufagin chemicals.[28]

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 do not show 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 strongly suggest 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.[29]

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