Photinus pyralis

Common Eastern fireflies are small soft-bodied beetles that are {{cvt |9 - 19|mm|in|1}} long. They have flat black or brown bodies with wing coverings, or elytra, that extend the length of their entire thorax and abdomen. The elytra have a yellow border. The head shield, or pronotum, is pale yellow, with a black dot in the center, surrounded by pink or red.

Both males and females of this species have light-emitting organs on the ventral side of their abdomens. While this organ extends the length of the last three segments of the males' abdomens, it appears only in the second to last segment of the females' abdomens.{{Cite journal |last1=Lewis |first1=Sara M |last2=Wong |first2=Choong Hay |last3=Owens |first3=Avalon C S |last4=Fallon |first4=Candace |last5=Jepsen |first5=Sarina |last6=Thancharoen |first6=Anchana |last7=Wu |first7=Chiahsiung |last8=De Cock |first8=Raphael |last9=Novák |first9=Martin |last10=López-Palafox |first10=Tania |last11=Khoo |first11=Veronica |last12=Reed |first12=J Michael |date=May 1, 2020 |title=Corrigendum: A Global Perspective on Firefly Extinction Threats |url=https://academic.oup.com/bioscience/article/70/5/440/5805567 |journal=BioScience |language=en |volume=70 |issue=5 |pages=440 |doi=10.1093/biosci/biaa026 |issn=0006-3568}}

Like most flying firefly species, Photinus pyralis is nocturnal.{{Cite web |date=February 20, 2024 |title=Firefly {{!}} Luminescent, Nocturnal, Bioluminescence {{!}} Britannica |url=https://www.britannica.com/animal/firefly-insect |access-date=March 1, 2024 |website=www.britannica.com |language=en}}

P. pyralis is widespread across the eastern half of North America.

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Common Eastern fireflies are found in a variety of habitats, ranging from temperate to tropical environments.{{Cite journal |last1=Catalan |first1=Ana |last2=Höhna |first2=Sebastian |last3=Lower |first3=Sarah E. |last4=Duchen |first4=Pablo |date=2022 |title=Inferring the demographic history of the North American firefly Photinus pyralis |url=https://academic.oup.com/jeb/article/35/11/1488-1499/7317918 |journal=Journal of Evolutionary Biology |language=en |volume=35 |issue=11 |pages=1488–1499 |doi=10.1111/jeb.14094 |pmid=36168726 |issn=1010-061X}} Some natural habitats of these fireflies include meadows, fields, wetlands, desert canyons, and dense forests, and while they can successfully thrive in all of these areas, they require moisture to survive at all life stages. They are especially drawn to areas with damp soil and long grasses to better conceal females and offspring.{{cite book |last1=Faust |first1=Lynn Frierson |title=Fireflies, Glow-worms, and Lightning Bugs |date=2017 |publisher=University of Georgia Press |isbn=978-0-8203-4872-8}}

Population studies have been done to investigate whether P. pyralis has always been endemic to the northeast regions of North America, especially because the species continues to occupy a wide variety of habitats across the continent. It has been discovered that ancestrally, the North American population originated in Texas during the Miocene epoch before migrating to the central states of the US and more recently, the Northeast coast. Through the tracking of single nucleotide polymorphisms (SNPs) along with other genetic markers, researchers have concluded that the common Eastern firefly possibly migrated during interglacial periods, which researchers suggest could account for the divergence to other Photinus species.

Like all beetles, the life cycle of a common Eastern firefly consists of four unique life stages starting with the egg, moving to the larval stage, followed by a pupa, before finally completing the cycle as a fully formed adult.

The time it takes for fireflies to complete all four stages can vary drastically by species, especially because they inhabit such a wide range of environments that the resources available to them vary significantly. However, all fireflies will spend most of their time in their feeding stage as larvae. P. pyralis sometimes takes as long as two years before it pupates. As a larva, P. pyralis lives under the soil and eats worms, slugs, and snails. As it grows, it will experience multiple instars, or molting periods. Because fireflies are very vulnerable during the larval stage, they have evolved to produce light as an aposematic signaling mechanism to drive away predators, regardless of whether or not they continue to be chemiluminescent in adulthood like the common Eastern firefly.{{Cite journal |date=November 1, 2007 |title=National Wildlife Federation field guide to insects and spiders & related species of North America |journal=Choice Reviews Online |volume=45 |issue=3 |pages=45–1461-45-1461 |doi=10.5860/choice.45-1461 |doi-broken-date=February 1, 2025 |issn=0009-4978}}

At the end of the larval stage, P. pyralis  will become a pupa. In 1 to 3 weeks, it will eclose, or emerge as an adult. The common Eastern firefly will live for approximately another three weeks to two months, during which time it will use its light to attract a mate.

Although their conservation status is classified as "Least Concern" by the IUCN Red List, these fireflies do face some dangers. The biggest threats to their populations include light pollution, pesticide use, climate change, and human building and development in their habitats.{{Cite report |url=https://www.iucnredlist.org/species/164046430/166771623 |title=Photinus pyralis: Walker, A.: The IUCN Red List of Threatened Species 2021: e.T164046430A166771623 |last=IUCN |date=September 10, 2020 |publisher=International Union for Conservation of Nature |doi=10.2305/iucn.uk.2021-1.rlts.t164046430a166771623.en |language=en |access-date=March 1, 2024 |archive-url=https://web.archive.org/web/20240119161431/https://www.iucnredlist.org/species/164046430/166771623 |archive-date=January 19, 2024 |url-status=live}}

Photinus pyralis contain steroid compounds called lucibufagins, which make them taste bad to potential predators, such as birds, bats, and other insects. However, some species of Photuris fireflies lack lucibufigins, and they prey on P. pyralis males in order to acquire the steroids for themselves. Although the lucibufagins are a defense mechanism for the most part, they can also serve as an attractant to some predators.{{cite journal|author=Eisner, T.|year=1997|title=Firefly "femmes fatales" acquire defensive steroids (lucibufagins) from their firefly prey|journal=Proc. Natl. Acad. Sci.|volume=94|issue=18 |pages=9723–9728|doi=10.1073/pnas.94.18.9723|pmid=9275191|pmc=23257|doi-access=free|bibcode=1997PNAS...94.9723E }} Beetles from the family Lampyridae have been known to use certain defenses such as unpleasant odour and the excretion of a sticky substance to avoid predation.{{cite journal |last1=Williams |first1=F.X. |year=1917 |title=Notes on the life-history of some North American Lampryridae |journal=Journal of the New York Entomology Society |volume=25 |pages=11–33}} Excretion of unpleasant fluids containing lucibufagins from the areas along the elytra and pronotum is the result of tactile stimulation and has been referred to as reflexive bleeding.{{cite journal |last1=Blum |first1=M. |last2=Sannasi |first2=A. |year=1973 |title=Reflex bleeding in the lampyrid Photinus pyralis: defensive function |journal=Journal of Insect Physiology |volume=20 |issue=3 |pages=451–660 |doi=10.1016/0022-1910(74)90153-x}}{{cite journal |last1=Meinwald |first1=J. |last2=Wiemer |first2=D.F. |last3=Eisner |first3=T. |year=1979 |title=Lucibufagins. 2. Esters of 12-Oxo-2p,5p, 1 1 a-trihydroxybufalin, the major defensive steroids of the Firefly Photinus pyralis (Coleoptera: Lampyridae) |journal=Journal of the American Chemical Society |volume=101 |issue=11 |pages=3055–3060 |doi=10.1021/ja00505a037}} This reflex bleeding is a defensive function of P. pyralis, as it can cause certain predators, such as ants, to become entangled in the sticky substance, or it can cause revulsion in others upon predation. Whereas adult flashing is used in mate signaling, pupae glow is thought to be an aposematic display for nocturnal predators.{{cite journal |last1=Underwood |first1=T.J. |last2=Tallamy |first2=D.W. |last3=Pesek |first3=J.D. |year=1997 |title=Bioluminescebce in firefly larvae: a test of the aposematic display hypothesis (Coleoptera: Lampyridae) |journal=Journal of Insect Behavior |volume=10 |issue=3 |pages=365–370 |bibcode=1997JIBeh..10..365U |doi=10.1007/bf02765604 |s2cid=27224813}}

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.Lloyd, J.E. 1966. Studies on the flash communication system in Photinus fireflies. Museum of Zoology, University of Michigan, Ann Arbor Male P. pyralis will flash every 5 to 7 seconds and wait for a responding flash from the female, which comes after a 1 to 2 second delay.{{cite journal |last1=Case |first1=J.F. |year=2004 |title=Flight studies on photic communication by the firefly Photinus pyralis |journal=Integrative and Comparative Biology |volume=44 |issue=3 |pages=250–258 |doi=10.1093/icb/44.3.250 |pmid=21676704 |doi-access=free}} The length of time between male flashes is temperature dependent, with shorter intervals as temperature increases. 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.{{cite journal | last1 = Lall | first1 = A.B | last2 = Worthy | first2 = K.M. | year = 2000 | title = Action spectra of the female's response in the firefly Photinus pyralis (Coleoptera: Lampyridae): evidence for an achromatic detection of the bioluminescent optical signal | journal = Journal of Insect Physiology | volume = 46 | issue = 6 | pages = 965–968 | doi = 10.1016/s0022-1910(99)00206-1 | pmid = 10802109 | bibcode = 2000JInsP..46..965L }} Females will twist their abdomen towards the male's 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 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.{{cite journal | last1 = Vencl | first1 = F.V. | year = 2004 | title = Allometry and proximate mechanisms of sexual selection in Photinus fireflies, and some other beetles | journal = Integrative and Comparative Biology | volume = 44 | issue = 3 | pages = 242–249 | doi = 10.1093/icb/44.3.242 | pmid = 21676703 | doi-access = free }}

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 favored. 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.{{cite journal | last1 = Vencl | first1 = F.V. | last2 = Carlson | first2 = D. | year = 1998 | title = Proximate mechanisms of sexual selection in the firefly Photinus pryalis (Coleoptera: Lampyridae) | journal = Journal of Insect Behavior | volume = 11 | issue = 2 | pages = 191–207 | doi = 10.1023/A:1021091806472 | s2cid = 37790195 }}

Among fireflies of the genus Photinus, males will first attract a female's  attention with their light flashing patterns, but once they reach the females they will be selected based on the size and quality of the "nuptial gifts" they can offer. These nuptial gifts, also known as spermatophores, are a combination of sperm and high levels of protein, hormones, defensive compounds, and other nutrients which the females will subsequently use to feed the eggs should she choose to mate with the male.{{Cite journal |last1=Lewis |first1=Sara M. |last2=Cratsley |first2=Christopher K. |date=2008-01-01 |title=Flash Signal Evolution, Mate Choice, and Predation in Fireflies |url=https://www.annualreviews.org/doi/10.1146/annurev.ento.53.103106.093346 |journal=Annual Review of Entomology |language=en |volume=53 |issue=1 |pages=293–321 |doi=10.1146/annurev.ento.53.103106.093346 |issn=0066-4170 |pmid=17877452|url-access=subscription }} During the adult stage of their lives, most Photinus fireflies do not eat, so all activity is fueled by energy that is consumed and subsequently stored during the larval stage; this becomes especially important regarding reproductive activity. Consequently, these nuptial gifts are a big factor in determining which male fireflies females choose to mate with. Although it ends up being a high cost to males, those with larger spermatophores tend to see increased reproductive success because they are able to provide females with more nutrients to sustain future offspring.{{Cite journal |last1=Al-Wathiqui |first1=Nooria |last2=Fallon |first2=Timothy R. |last3=South |first3=Adam |last4=Weng |first4=Jing-Ke |last5=Lewis |first5=Sara M. |date=2016-12-22 |title=Molecular characterization of firefly nuptial gifts: a multi-omics approach sheds light on postcopulatory sexual selection |journal=Scientific Reports |language=en |volume=6 |issue=1 |pages=38556 |bibcode=2016NatSR...638556A |doi=10.1038/srep38556 |issn=2045-2322 |pmc=5177949 |pmid=28004739}}

It was found that females were more likely to mate with virgin males who had never mated because their nuptial gift sizes were larger in comparison to males who had mated the previous night.{{Cite journal |last1=South |first1=A |last2=Lewis |first2=S.M. |date=25 April 2012 |title=Determinants of reproductive success across sequential episodes of sexual selection in a firefly |journal=Proceedings of the Royal Society B: Biological Sciences |volume=279 |issue=1741 |pages=3201–3208 |doi=10.1098/rspb.2012.0370 |pmc=3385720 |pmid=22535779}}

The female common Eastern firefly is polyandrous, meaning it will mate with multiple males over multiple nights, although it will only mate with a single male in one night. This practice has been shown to increase female fecundity as well as overall lifespan.

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File:Firefly Luciferase Crystal Structure.rsh.png

The light organ of P. pyralis 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.Beams, H.W. and Anderson, E. 1955. Light and electron microscope studies on the light organ of the firefly (Photinus pyralis). The Biological Bulletin, 375-393 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.{{cite journal |last1=Keller |first1=G.A. |last2=Gould |first2=S. |last3=Deluca |first3=M. |last4=Subramani |first4=S. |year=1987 |title=Firefly luciferase is targeted to peroxisomes in mammalian cells |journal=Proceedings of the National Academy of Sciences |volume=84 |issue=10 |pages=3264–3268 |bibcode=1987PNAS...84.3264K |doi=10.1073/pnas.84.10.3264 |pmc=304849 |pmid=3554235 |doi-access=free}} Luciferase requires oxygen, luciferin and adenosine triphosphate (ATP) to catalyze a chemical reaction that produces bioluminescence in these insects.{{cite web |last=Branchini |first=Bruce R. |date=2013-08-02 |title=Chemistry of Firefly Bioluminescence |url=http://photobiology.info/Branchini2.html |website=Photobiological Sciences Online |publisher=American Society for Photobiology |editor1-last=Lee |editor1-first=John |editor2-last=Smith |editor2-first=Kendric C. |access-date=2024-03-22}} 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.Hastings, J.W. and Buck, J. 1965. The firefly pseudoflash in relation to photogenic control. The Biological Bulletin, 101-113 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.

Much research has been done to both figure out the mechanism by which fireflies can emit light as well as how that tool can be used advantageously in biotechnological contexts. Luciferase has become a tool for many different research strategies. In 2018 the Photinus pyralis genome sequence was published.{{Cite journal |last1=Fallon |first1=Timothy R |last2=Lower |first2=Sarah E |last3=Chang |first3=Ching-Ho |last4=Bessho-Uehara |first4=Manabu |last5=Martin |first5=Gavin J |last6=Bewick |first6=Adam J |last7=Behringer |first7=Megan |last8=Debat |first8=Humberto J |last9=Wong |first9=Isaac |last10=Day |first10=John C |last11=Suvorov |first11=Anton |last12=Silva |first12=Christian J |last13=Stanger-Hall |first13=Kathrin F |last14=Hall |first14=David W |last15=Schmitz |first15=Robert J |date=2018-10-16 |title=Firefly genomes illuminate parallel origins of bioluminescence in beetles |journal=eLife |language=en |volume=7 |doi=10.7554/eLife.36495 |doi-access=free |pmid=30324905 |pmc=6191289 |issn=2050-084X}}

The first use of luciferase was as a reporting marker in many high throughput assays. Because it is known that luciferase is activated by oxygen, luciferin, and ATP, the assays were specifically pertaining to reduction-oxidation reactions that occurred in various organisms. It is a highly sensitive marker and is very easy and efficient to use, so it is very widely used among scientists. Recent studies have shown that the luciferase protein has been found specifically in peroxisomes of many eukaryotes, the organelles{{cite book | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK21052/#A5609 | title=Molecular Biology of the Cell. 4th edition | chapter=Glossary | date=2002 | publisher=Garland Science }} responsible for carrying out oxidative reactions and producing hydrogen peroxide as a byproduct that is quickly removed. More research is being done about how this information can be used for further advancement in the field of molecular and cell biology.{{Cite journal |last1=Gould |first1=Stephen J. |last2=Subramani |first2=Suresh |date=29 November 2004 |title=Firefly Luciferase as a Tool in Molecular and Cell Biology |url=https://pubmed.ncbi.nlm.nih.gov/3072883/ |journal=Analytical Biochemistry |volume=175 |issue=1 |pages=5–13 |doi=10.1016/0003-2697(88)90353-3 |pmid=3072883 |via=National Library of Medicine}}

{{Reflist|2}}

{{Commons category|Photinus pyralis}}

• [http://bugguide.net/node/view/63819 BugGuide] with details of Photinus pyralis

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Category:Lampyridae

Category:Bioluminescent insects

Category:Beetles described in 1767

Category:Beetles of North America

Category:Taxa named by Carl Linnaeus