The common eastern firefly, or North American firefly, ranges throughout the United States east of the Rocky Mountains.
Biogeographic Regions: nearctic (Native )
The common eastern firefly is, in fact, not a fly, but a type of beetle. The average adult is dark brown and 10-14 mm long. Like all insects, it has a hard exoskeleton, six jointed legs, two antennae, compound eyes, and a body divided into three parts head, thorax, and abdomen). Its head has a rounded cover outlined in yellow and accented with two orange spots. Photinus pyralis also has two pairs of wings. The first pair, the elytra, form a cover over the second pair and is dark brown with narrow yellow side margins. Only males use the second pair for flying; females usually have short wings, and do not fly. The last segment of the abdomen is the section that lights up, flashing bright yellow-green.
Common eastern firefly larvae are characterized by six legs, a pair of antennae, and a flattened segmented abdomen. Upon emerging from the egg they are generally about 1.6 mm in length. By the end of its larval stage it will have grown to about 10.3 mm. Firefly larvae are often referred to as "glow worms" because, like the adults, they emit a glow of light.
Range length: 10 to 14 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes shaped differently
Larvae of the common eastern firefly most often inhabit moist places such as on the ground, under bark, and near streams. Adult fireflies can be found from late spring to early fall in meadows, woodland edges, and near streams.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Other Habitat Features: suburban ; agricultural ; riparian
Both adult and larval Phorinua pyralis are carnivorous. They feed on other insects (including other fireflies), earthworms, and snails. When feeding, they inject poison to immobilize and liquefy their prey. This allows the fireflies or larvae to suck up their meal.
Animal Foods: insects; mollusks; terrestrial worms
Primary Diet: carnivore (Insectivore , Molluscivore , Vermivore)
Flowering Plants Visited by Photinus pyralis in Illinois
(observations are from Robertson)
Apiaceae: Pastinaca sativa sn (Rb), Sium suave sn (Rb); Asclepiadaceae: Asclepias syriaca [plpr sn] (Rb); Liliaceae: Melanthium virginicum sn (Rb)
An interesting predator of Photinus pyralis is the female Photuris pyralis. This firefly mimics the signal of the female Photinus pyralis and lures male Photinus pyralis that are expecting to mate. However, when the male common eastern firefly reaches this mimicking species, he quickly becomes the female predator's meal.
- Photuris pyralis
Life History and Behavior
Communication Channels: visual
Other Communication Modes: photic/bioluminescent
Perception Channels: visual
Firefly eggs, which also emit a slight glow, hatch after four weeks into flightless larvae, the longest stage of the firefly life cycle. Larvae live one to two years and can be seen glowing on damp ground and near streams. After passing through the larval stage, the developing firefly moves into chambers in the moist soil and pupates. While pupating, it undergoes metamorphosis, emerging from the pupa as an adult.
Development - Life Cycle: metamorphosis
Adult Photinus pyralis live 5 to 30 days.
Status: wild: 5 to 30 days.
Fireflies use specific flashing signals to find a mate. Females wait on the ground for passing males to flash their signal, and then answer with their own specific signal. It is this communication that allows the male to find a female with whom he mates.
Mating System: polygynandrous (promiscuous)
Fireflies use specific flashing signals to find a mate. Females wait on the ground for passing males to flash their signal, and then answer with their own specific signal. It is this communication that allows the male to find a female with whom he mates. This dating game occurs in summer and early fall, and the female generally lays about 500 eggs on damp soil during this time of year.
Average eggs per season: 500.
Key Reproductive Features: semelparous ; seasonal breeding ; sexual ; fertilization (Internal ); oviparous
Evolution and Systematics
Fireflies inhale oxygen and exhale light with help from an enzyme.
"In a firefly bioluminescence reaction, an enzyme known as a luciferase uses adenosine triphosphate (ATP) to activate a molecule called a luciferin. The product of this reaction combines with molecular oxygen to produce an excited-state oxyluciferin species. When oxyluciferin relaxes back to its ground state, energy is released in the form of light…Jellyfish-like animals called ctenophores—can do without [ATP to jump-start bioluminescence]. Instead, they use a luciferin of intrinsically higher energy and prepackage it with oxygen in an enzyme known as a photoprotein. Calcium activates the reaction by changing the shape of the photoprotein, which releases the invested energy in the form of light." (Pepling 2006:36)
Learn more about this functional adaptation.
Molecular Biology and Genetics
Barcode data: Photinus pyralis
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Photinus pyralis
Public Records: 2
Specimens with Barcodes: 3
Species With Barcodes: 1
This species does not require any special status.
US Federal List: no special status
CITES: no special status
Relevance to Humans and Ecosystems
There is no known negative economic importance for humans.
The chemical utilized by the common eastern firefly for bioluminescence is a complex organic compound, luciferase. Fireflies have recently been harvested by the biochemical industry for this important compound. Researchers discovered a technique to splice the gene containing luciferase into the DNA of other plants and animals. They use this in tracing the inheritance of a particular disease-resistant gene by splicing the bioluminescence gene into the disease-resistant gene in a parent plant or animal. The disease-resistant gene can then be traced in the offspring, because if it is inherited, it will glow.
Positive Impacts: source of medicine or drug
Photinus pyralis, known by the common names common eastern firefly and big dipper firefly, is the most common species of firefly in North America. P. pyralis is a flying and light producing beetle with a light organ on the ventral side of its abdomen. This organism is sometimes incorrectly classified as Photuris pyralis, which likely results from mistaking the similar sounding genus Photuris.
The Photuris female may also lure a Photinus pyralis to be eaten to obtain spider-repellent steroids which Cornell researchers named "lucibufagins" in 1997. In males the light organ covers the entire ventral surface of the three most posterior segments and in females it only covers a portion of the third posterior segment. These fireflies are most noticeable around twilight, in the early part of the evening and hover close to the ground. The species' common name refers to the characteristic flight of the male, which flies in a J-shaped trajectory, lighting on the upswing. During flight, the J-shaped flight pattern is used in combination with patrolling flash patterns while seeking a mate. Their flashes are stimulated by light conditions, not by rhythmic impulses as originally thought 
Males of Photinus pyralis locate females by a series of light flashes, to which females respond with a coded delay flash. The light organ of P. pryalis is composed of two layers; a layer of refractile cells on the dorsal side and a photic layer with light producing cells on the ventral side. The light organ (specifically the photogenic layer) is supplied with numerous tracheal branches, which are thought to provide the required oxygen for light production. The light producing enzyme is luciferase, and is found within cells of the lantern. Luciferases require oxygen, luciferin and adenosine triphosphate (ATP) to catalyze a chemical reaction that produces bioluminescence in these insects. It has been shown that the glow is not controlled by the tracheal end cells (which were thought to contain valves) nor by central nerve impulses through studies involving low oxygen conditions. Pupae of these beetles have different light organs than the adult. They do not have the characteristic tracheal end cells of the flashing adults, and whereas the adults emit bright flashes, pupae emit low intensity glowing.
Beetles from the family Lampyridae have been known to use certain defenses such as unpleasant odor and the excretion of a sticky substance to avoid predation. Excretion of unpleasant fluids from the areas along the elytra and pronotum is the result of tactile stimulation and has been referred to as reflexive bleeding. This reflex bleeding is a defensive function of P.pyralis, as it can cause certain predators to become entangled in the sticky substance (such as ants) or cause revulsion in others upon predation. The excretion contains lucibufagins, steroids found in P. pyralis that render them distasteful to certain bird predators. Whereas adult flashing is used in mate signaling, pupae glow is thought to be an aposematic display for nocturnal predators.
In relation, males of the Photinus species are the prey for females of a different genus, Photuris. Photuris females actually mimic the effects of the Photinus males light-signaling patterns, and by doing this the females lure in the Photinus males. The males naturally produce the steroid lucibufagin, and the reason that the females prey on these males is to obtain this steroid. Once the females prey on the Photinus males, the females gain the steroid lucibufagin to use to their defense against jumping spiders. A study was performed where the Photuris females were collected from nature and forced to reflex bleed which contains the steroid lucibufagin. It was found that when the females were forced to reflex bleed, the samples taken from each female had different amounts of the steroid in each sample. So after experiments were brought out to see which females the jumping spiders would eat it was decided that the jumping spiders were more likely to eat the females with less lucibufagin inside their bodies and the females with more were constantly rejected by the spiders therefore protecting themselves from predation.
Males are the first to start the series of patrolling flashes needed to locate and mate with a female. Males will actively fly while flashing, whereas females are sedentary. They will flash every 6 seconds and wait for a responding flash from the female, which comes after a 1-2 second delay  It has been shown that females only respond to their conspecific males; identifying them by the color of their yellow bioluminescent flash, in combination with the temporal patterning, duration and intensity of the male flash. Females will twist their abdomen towards the males flash, presenting their own flash toward the male. Males can be observed flying in a nearly vertical orientation; their antennae held forward and stiff while their legs are held toward the body during patrolling. They also show an obvious gaze shift towards the last female flash, and continue towards it until the female firefly flashes again. The flashes continue until the male reaches the female. Males congregate in large masses and it is most likely that more than one will find the same female; in this case male P. pyralis display aggression towards one another while not in flight.
During the “aggression” stage, males with smaller elytra and smaller lanterns are favored; whereas during the signaling phase, males with longer elytra and bigger lanterns are favoured. Males with larger lanterns are favored in signaling phases of courtship because their broadcasting flashes can be seen by females who are further away, it is also suggested that due to their longer elytra these males may also have an advantage of finding the females faster. Adult Photinus fireflies do not feed as adults  and therefore males are better able to attract females by offering nuptial food gifts, in the form of spermatophores which females can use to provide nutrients to their eggs.
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- Animal Pictures Archive
- "Firefly Companion and Letter Winter 1993-1994" (PDF) 1 (1). Archived from the original on June 30, 2007. Retrieved January 12, 2009.
- State Symbols USA: Tennessee State Insect
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- [dead link]
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