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Photuris versicolor

By Kelly Sharp

Geographic Range

All species of the genus Photuris are restricted to North America, and are most commonly found east of Texas and south of Manitoba. (Eisner, et al., September 1997; Milne and Milne, 1980)

Habitat

Photuris versicolor occupy meadows, woods, cosmopolitan areas, and forests within North America. Although they fly a few feet above ground while mating, they live mostly under debris such as bark or decaying vegetation on the ground. (Milne and Milne, 1980)

Physical Description

P. versicolor ranges from 20mm-50mm in length, and is brownish-blackish in color. Like all members of the order Coleoptera, P. versicolor has a thickened pair of forewings called elytra that meet at the midline to cover the membranous hind wings. The mouth has four main components: mandibles, maxillae, upper lip (labrum), and lower lip (labium). The mandibles cut and pierce food, while the other mouthparts prepare it for digestion and push it down the esophagus. Most sensory organs are found on the head, including the compound eyes that can see in color. P. versicolor has a highly elongated crystallized cone, called an exocone, extending from the lens of the eye that collects light; P. versicolor needs highly developed light sensory organs because its mating habits depend on light flashes. In addition to sensory organs found on the head, P. versicolor has sensors on the thorax, abdomen, and legs that are sensitive to vibration stimulus. Photuris versicolor emits a faint greenish-yellowish luminescence. Larvae also emit a faint sporadic glow, by which researchers can identify them. Male and female adults are actively (and equally) luminescent, however, sexual dimorphism exists - females are larger and stronger than males. (Blum, 1985; Milne and Milne, 1980; O'Toole, 1986; Preston-Mafham, 1993)

  • Sexual Dimorphism
  • female larger

Development

Eggs undergo complete metamorphosis from larvae to adulthood, with a resting pupal state and a predacious larval state in between. The new adult fireflies will emerge again at the beginning of the next summer. (Eisner, et al., September 1997; Milne and Milne, 1980; Preston-Mafham, 1993)

Reproduction

Photuris emerge from their pupae in early summer, and mate during the subsequent warm months. Courtship is nocturnal, and is done via flashing signals: like all Lampyridae (fireflies), P. versicolor has species-specific flashes, which are species-specific in the duration of the flash, the length of time between flashes, the flash color, and the height at which the flasher flies. Males fly a few feet above ground in an up-down motion, flashing on the upswing. Females remain sedentary on the ground or on low vegetation. Females emit one flash in response (their timing is also species-specific) and a male goes to her to mate. P. versicolor has its own species-specific flash patterns, but many P. versicolor males mate by imitating the flashes of other species. This is because female Photuris are often more interested in food than in mating, so male Photuris mimic the flash patterns of species on which female Photuris prey. By doing so, they are able to get close enough to the female to mate, although it may be a kamikaze maneuver since the stronger, more powerful females sometimes eat the male after copulation. Once a male is close enough to a female he will attempt to copulate with her, assuming she is sexually active. (Eisner, et al., September 1997; Milne and Milne, 1980; Preston-Mafham, 1993)

Behavior

Like all fireflies, P. versicolor use bioluminescence to communicate. There are three main purposes for luminescence: the first and most important is as a mating signal, the second is as a "flashlight" that guides landing and walking, and the third is as intimidation to predators. Luminescence occurs when the catalyst luciferase oxidizes luciferen in the presence of ATP, oxygen, and magnesium ions. Fireflies control their flashes by controlling the oxygen supply in the 6th and 7th segments of their bodies, where illumination takes place. The light itself exists in the visible spectrum between 415 and 670 nm, and in the case of P. versicolor is a greenish-yellow color. The most fascinating aspect of P. versicolor behavior (and an aspect that currently classifies it as a species) is its ability to mimic the mating flash patterns of other species. Female P. versicolor practice mimicry in order to eat male fireflies of other species and therefore acquire lucibufagins, which make Photuris unpalatable to thrushes (and probably other birds) as well as to most predatory spiders. After acquiring these pyrones, females pass them on to their eggs. It is uncertain how males acquire these pyrones, though in a laboratory environment, male Photuris attacked and ate male Photinus. Male P. versicolor are also excellent imitators, though they mostly use mimicry not to attract other species, but to attract other female P. versicolor. Besides eating Photinus to acquire pyrones, another interesting defensive mechanism in P. versicolor is their tendency to "reflex bleed," or emit droplets of blood in situations of distress. The lucibufagins present in the blood are released with this "reflex bleeding," and some predators will be repulsed by these noxious chemicals. The bleeding does not seem to negatively affect P. versicolor. (Eisner, et al., September 1997; Stous, 1997)

Communication and Perception

Photuris versicolor have compound eyes that can see in color. P. versicolor has a highly elongated crystallized cone, called an exocone, extending from the lens of the eye that collects light; P. versicolor needs highly developed light sensory organs because its mating habits depend on light flashes. In addition to sensory organs found on the head, P. versicolor has sensors on the thorax, abdomen, and legs that are sensitive to vibration stimulus. Photuris versicolor emits a faint greenish-yellowish luminescence. (Blum, 1985; Milne and Milne, 1980; O'Toole, 1986; Preston-Mafham, 1993)

  • Communication Channels
  • visual

Food Habits

Both larvae and adults are predacious, feeding on soft-bodied insects, snails, slugs, mites and other fireflies - mostly Photinus and some Photuris species. Female Photuris prey on male Photinus not only for a good meal, but also to acquire lucibufagins, which are steroid pyrones that make Photuris unpalatable to predators, but which Photuris cannot produce on its own. All species within the genus Photuris prey on other species of firefly by imitating their mating flash patterns, however, P. versicolor is most efficient, for it can mimic eleven different species of firefly. Female Photuris lure males of other species by imitating the sexual female response to those males' mating signals; once the prey is close enough, the larger, stronger female pounces on the male and devours him. Male Photuris also need lucibufagins, and researchers are yet uncertain as to how they get those. (Eisner, et al., September 1997; Ross, 1976; Stous, 1997)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • mollusks

Economic Importance for Humans: Positive

Photuris versicolor has no positive economic benefits for humans.

Economic Importance for Humans: Negative

Photuris versicolor has no negative economic effects for humans.

Conservation Status

Photuris versicolor is not a threatened species.

Other Comments

Photuris versicolor has the ability to mimic other fireflies and lure them to their death. This creates a taxonomic puzzle, since scientists identify fireflies by their flashes, and often it is hard to determine whether a Photuris flash is genuinely its own species-specific flash or whether it is an imitation of another species. Therefore, there may be further subdivisions not yet recognized due to complications in the study of P. versicolor. (Eisner, et al., September 1997)

Contributors

Sara Diamond (editor), Animal Diversity Web.

Kelly Sharp (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

insectivore

An animal that eats mainly insects or spiders.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

photic/bioluminescent

generates and uses light to communicate

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

sedentary

remains in the same area

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

Blum, M. 1985. Fundamentals of Insect Physiology. New York: John Wiley and Sons, Inc..

Eisner, T., M. Goetz, D. Hill, S. Smedley, J. Meinwald. September 1997. Firefly femmes fatales acquire defensive steroids (lucibufagins) from their firefly prey. Proceedings of the National Academy of Sciences of the United States of America, 94, no. 18: 9723-9728.

Milne, L., M. Milne. 1980. Audubon Society Field Guide to Insects. New York: Alfred A. Knopf.

O'Toole, C. 1986. Encyclopedia of Insects. New York: Facts on File Publications.

Preston-Mafham, R. 1993. Encyclopedia of Land Invertebrate Behavior. Cambridge, Massachusets: MIT Press.

Ross, H. 1976. A Textbook of Entomology. New York: John Wiley and Sons, Inc..

Stous, H. 1997. "Insect Behavior Review Articles" (On-line). Accessed April 20, 2001 at http://www.colostate.edu/Depts/Entomology/courses/en507/papers_1997/stous.html.

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