Mayflies are insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s which belong to the Order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Ephemeroptera (from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

  = "short-lived", = "wing
Insect wing
Insects are the only group of invertebrates known to have evolved flight. Insects possess some remarkable flight characteristics and abilities, still far superior to attempts by humans to replicate their capabilities. Even our understanding of the aerodynamics of flexible, flapping wings and how...

", referring to the brief lifespan of adults). They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...

 and damselflies
Damselflies are insects in the order Odonata. Damselflies are similar to dragonflies, but the adults can be distinguished by the fact that the wings of most damselflies are held along, and parallel to, the body when at rest...

. They are aquatic insects
Aquatic insects
Aquatic insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.-Breathing:...

 whose immature stage (called "naiad" or, colloquially, "nymph
Nymph (biology)
In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...

") usually lasts one year in freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

. The adults are short-lived, from a few minutes to a few days depending on the species. About 2,500 species are known worldwide, including about 630 species in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. Common names for mayflies include "dayfly", "shadfly", "Green Bay fly", "lake fly", "fishfly" (in the Great Lakes region
Great Lakes region (North America)
The Great Lakes region of North America, occasionally known as the Third Coast or the Fresh Coast , includes the eight U.S. states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania and Wisconsin as well as the Canadian province of Ontario...

 of North America), "midgee", "canadian soldiers" and "jinx fly".


Eggs are laid on the surface of lakes or streams, and sink to the bottom. Naiads
Nymph (biology)
In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...

Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...

 20 to 30 times over a period of a few months up to a year, depending on the species. The naiads live primarily in streams under rocks, decaying vegetation, or in the sediment. Few species live in lakes, but they are among the most prolific. For example, the emergence of one species of Hexagenia was recorded on doppler weather radar along the shores of Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...


Most species feed on algae or diatoms, but there are a few predatory
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

 species. The naiad stage may last from several months to several years, with a number of moults
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...

 along the way. Most mayfly naiads are distinctive in having seven pairs of gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s on the dorsum
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...

 of the abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

. In addition, most possess three long cerci
Cerci are paired appendages on the rear-most segments of many arthropods, including insects and arachnids but not crustaceans. Cerci often serve as sensory organs, but they may also be used as weapons or copulation aids, or they may simply be vestigial structures.Typical cerci may appear to be...

 or tails at the end of their bodies. Some species, notably in the genus Epeorus, have only two tails. In the last aquatic stage, dark wingpads are visible. Developmentally, these insects are considered hemimetabolous
Hemimetabolism or hemimetaboly, also called incomplete metamorphosis, is a term used to describe the mode of development of certain insects that includes three distinct stages: the egg, nymph, and the adult stage, or imago. These groups go through gradual changes; there is no pupal stage...

 insects. A more casual and familiar term is "incomplete metamorphosis
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...

". Mayflies are unique among insects in that they moult one more time after acquiring functional wings (this is also known as the alate
An alate is a winged reproductive of a social insect . Alate females are typically those destined to become queens , whereas alate males are occasionally referred to as "drones"...

 stage); this last-but-one winged instar usually lives a very short time, often a matter of hours, and is known as a subimago or to fly fishermen as a dun. Mayflies in this stage are a favourite food of many fish, and many fishing flies
Artificial fly
An artificial fly or fly lure is a type of fishing lure, usually used in the sport of fly fishing . In general, artificial flies are the bait which fly fishers present to their target species of fish while fly fishing...

 are modeled to resemble them.


The lifespan of an adult mayfly is very short and varies depending on the species. The primary function of the adult is reproduction; the mouthparts
Insect mouthparts
Insects exhibit a range of mouthparts, adapted to particular modes of feeding. The earliest insects had chewing mouthparts...

 are vestigial, and the digestive system is filled with air.

The wings are membranous, with extensive venation, and are held upright like those of a butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

. The hindwings are much smaller than the forewings, and may be vestigial or absent. The second segment of the thorax
Thorax (insect anatomy)
The thorax is the mid section of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma in other arthropods....

, which bears the forewings, is enlarged, holding the main flight muscles.

Adults have short, flexible antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....

, large compound eyes and three ocelli. In most species, the males' eyes are large and the front legs unusually long, for use in locating and grasping females during mid-air mating. In some species, all legs aside from the males' front legs are useless. Uniquely among insects, mayflies possess paired genitalia, with the male having two penis
The penis is a biological feature of male animals including both vertebrates and invertebrates...

es and the female two gonopore
A gonopore, sometimes called a gonadopore, is a genital pore in many invertebrates. Hexapods, including insects have a single common gonopore, except mayflies, which have a pair of gonopores...

s. The abdomen is roughly cylindrical, with ten segments and two long cerci
Cerci are paired appendages on the rear-most segments of many arthropods, including insects and arachnids but not crustaceans. Cerci often serve as sensory organs, but they may also be used as weapons or copulation aids, or they may simply be vestigial structures.Typical cerci may appear to be...

 at the tip.


The final molt of the naiad is not to the full adult form, but to a winged subimago that physically resembles the adult, but which is usually sexually immature. The subimagos are generally poor fliers, and typically lack the colouration patterns used to attract mates. The subimago eventually moults to the full adult, making mayflies the only insects where a winged form undergoes moulting.

Like the adult, the subimago stage does not last for long, rarely for more than 24 hours. In some species, it may last for just a few minutes, while the mayflies in the family Palingeniidae have sexually mature subimagos and no true adult form at all.


Because of its short lifespan, the mayfly is called one-day or one-day fly in some languages — German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

 , Dutch
Dutch language
Dutch is a West Germanic language and the native language of the majority of the population of the Netherlands, Belgium, and Suriname, the three member states of the Dutch Language Union. Most speakers live in the European Union, where it is a first language for about 23 million and a second...

 , Slovenian , Swedish
Swedish language
Swedish is a North Germanic language, spoken by approximately 10 million people, predominantly in Sweden and parts of Finland, especially along its coast and on the Åland islands. It is largely mutually intelligible with Norwegian and Danish...

 , Danish
Danish language
Danish is a North Germanic language spoken by around six million people, principally in the country of Denmark. It is also spoken by 50,000 Germans of Danish ethnicity in the northern parts of Schleswig-Holstein, Germany, where it holds the status of minority language...

 and Norwegian
Norwegian language
Norwegian is a North Germanic language spoken primarily in Norway, where it is the official language. Together with Swedish and Danish, Norwegian forms a continuum of more or less mutually intelligible local and regional variants .These Scandinavian languages together with the Faroese language...

 , Polish
Polish language
Polish is a language of the Lechitic subgroup of West Slavic languages, used throughout Poland and by Polish minorities in other countries...

 , Finnish
Finnish language
Finnish is the language spoken by the majority of the population in Finland Primarily for use by restaurant menus and by ethnic Finns outside Finland. It is one of the two official languages of Finland and an official minority language in Sweden. In Sweden, both standard Finnish and Meänkieli, a...

 , Turkish
Turkish language
Turkish is a language spoken as a native language by over 83 million people worldwide, making it the most commonly spoken of the Turkic languages. Its speakers are located predominantly in Turkey and Northern Cyprus with smaller groups in Iraq, Greece, Bulgaria, the Republic of Macedonia, Kosovo,...

 , Russian
Russian language
Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...

 , Bulgarian
Bulgarian language
Bulgarian is an Indo-European language, a member of the Slavic linguistic group.Bulgarian, along with the closely related Macedonian language, demonstrates several linguistic characteristics that set it apart from all other Slavic languages such as the elimination of case declension, the...

 , and Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 . The Greek name, transliterated efímeros, is the origin of the names in Romance languages: French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

 éphémère, Italian
Italian language
Italian is a Romance language spoken mainly in Europe: Italy, Switzerland, San Marino, Vatican City, by minorities in Malta, Monaco, Croatia, Slovenia, France, Libya, Eritrea, and Somalia, and by immigrant communities in the Americas and Australia...

 effimera, Portuguese
Portuguese language
Portuguese is a Romance language that arose in the medieval Kingdom of Galicia, nowadays Galicia and Northern Portugal. The southern part of the Kingdom of Galicia became independent as the County of Portugal in 1095...

 efêmera, Spanish
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

 , and Romanian
Romanian language
Romanian Romanian Romanian (or Daco-Romanian; obsolete spellings Rumanian, Roumanian; self-designation: română, limba română ("the Romanian language") or românește (lit. "in Romanian") is a Romance language spoken by around 24 to 28 million people, primarily in Romania and Moldova...

 . In Korean
Korean language
Korean is the official language of the country Korea, in both South and North. It is also one of the two official languages in the Yanbian Korean Autonomous Prefecture in People's Republic of China. There are about 78 million Korean speakers worldwide. In the 15th century, a national writing...

 harusarimok (하루살이목). In Chinese
Chinese language
The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...

 fu you (蜉蝣).

It often happens that all the mayflies in a population mature at once (a hatch), and for a day or two in the spring or fall, mayflies will be everywhere, dancing around each other in large groups, or resting on every available surface. The species Polingenia longicauda hatches in mid-June on the Maros River
Mures River
The Mureș is an approximately 761 km long river in Eastern Europe. It originates in the Hășmașu Mare Range in the Eastern Carpathian Mountains, Romania, and joins the Tisza river at Szeged in southeastern Hungary....

 and the Tisza River in Serbia
Serbia , officially the Republic of Serbia , is a landlocked country located at the crossroads of Central and Southeast Europe, covering the southern part of the Carpathian basin and the central part of the Balkans...

 and Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...

. It is called the in Hungarian and in Serbian. Both names mean "Tisza flower", and the phenomenon is called Tisza blooming. In regions of New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

 and Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, mayflies are eaten when they emerge en masse.


The status of most species of mayflies is unknown because many species are only known from the original collection data. Four North American species are believed to be extinct, two of which are listed below:
  • Pentagenia robusta
    Pentagenia robusta
    Pentagenia robusta was a species of insect in family Ephemeridae. It was endemic to the United States.-Source:* World Conservation Monitoring Centre 1996. . Downloaded on 10 August 2007....

    was originally collected from the Ohio River
    Ohio River
    The Ohio River is the largest tributary, by volume, of the Mississippi River. At the confluence, the Ohio is even bigger than the Mississippi and, thus, is hydrologically the main stream of the whole river system, including the Allegheny River further upstream...

     near Cincinnati, but this species has not been seen since its original collection in the 1800s.

  • Ephemera compar was reported from the "foothills of Colorado". Despite intensive surveys of the Colorado mayflies, this species has not been collected in the past 50 years.

The International Union for Conservation of Nature (IUCN) red list
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

 of threatened species includes one mayfly: Tasmanophlebi lacus-coerulei
Tasmanophlebi lacus-coerulei
Tasmanophlebi lacus-coerulei is a species of insect in family Siphlonuridae. It is endemic to Australia.-References:* World Conservation Monitoring Centre 1996. . Downloaded on 10 August 2007....

, the large blue lake mayfly, is a native of Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and is listed as vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...



Suborder Schistonota
  • Superfamily Baetoidea
    • Siphlonuridae
    • Baetidae
      Baetidae is a family of mayflies with about 900 described species distributed worldwide. These are among the smallest of mayflies, adults rarely exceeding 10 mm in length excluding the two long slender tails and sometimes much smaller, and members of the family are often referred to as small...

    • Oniscigastridae
    • Ameletopsidae
    • Ametropodidae
  • Superfamily Heptagenioidea
    • Coloburiscidae
    • Oligoneuriidae
    • Isonychiidae
    • Heptageniidae
      Heptageniidae is a family of mayflies with over 500 described species mainly distributed in the Holarctic, Oriental, and Afrotropical regions, and also present in the Central American Tropics and extreme northern South America. These are generally rather small mayflies with two long tails...

  • Superfamily Leptophlebioidea
    • Leptophlebiidae
      Leptophlebiidae is a family belonging to the Ephemeropterans that are commonly known as the prong-gilled mayflies or leptophlebiids. In North America they occur with about 70 species from 9 genera in freshwater streams and lakes; in Europe they are somewhat less diverse. Globally, this family is...

  • Superfamily Ephemeroidea
    • Behningiidae
    • Potamanthidae
    • Euthyplociidae
    • Polymitarcydae
    • Ephemeridae
      Ephemeridae is a family of mayflies with about 150 described species found throughout the world except Australia and Oceania. These are generally quite large mayflies with either two or three very long tails...

    • Palingeniidae

Suborder Pannota
  • Superfamily Ephemerelloidea
    • Ephemerellidae
      Ephemerellidae are known as the Spiny Crawler Mayflies. They are a family of the order Ephemeroptera. There are 8 genera consisting of a total 90 species . They are distributed throughout North America as well as the UK. Their habitat is lotic-erosional, they are found in all sizes of flowing...

    • Leptohyphidae
      Leptohyphidae is a family of mayflies with some 140 described species in 12 genera....

    • Tricorythidae
  • Superfamily Caenoidea
    • Neoephemeridae
    • Baetiscidae
    • Caenidae
      Caenidae, or the Small Squaregill Mayflies, is a family of insects consisting of 4 genera comprising 26 individual species. They are found throughout North America in lotic, depostional environments, and they are sprawlers. Caenids occur in quiet and even stagnant water and are often overlooked...

    • Prosopistomatidae

Fossil record and evolution

Mayflies are a very old group of pterygote insects. Putative fossil stem group representatives (e.g. Syntonopteroidea like Lithoneura lameerrei) are already known from the late Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

. The largest mayfly of all times may have been Bojophlebia prokopi from the Upper Carboniferous of Moravia
Moravia is a historical region in Central Europe in the east of the Czech Republic, and one of the former Czech lands, together with Bohemia and Silesia. It takes its name from the Morava River which rises in the northwest of the region...

 with a wing span of 45 cm. From the Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

 numerous stem group representatives of mayflies are known, which are often lumped into a separate taxon Permoplectoptera (e.g. including Protereismatidae and Misthodotidae). The larvae of Permoplectoptera still had 9 pairs of abdominal gills, and the adults still had long hind wings. Maybe the fossil family Cretereismatidae from the Lower Cretaceous Crato Formation
Crato Formation
The Crato Formation is a geologic formation of Early Cretaceous age in northeastern Brazil's Araripe Basin. It is an important Lagerstätte for palaeontologists. The strata were laid down mostly during the early Albian age, about 108 million years ago, in a shallow inland sea...

 of Brazil also belongs as last offshot to Permoplectoptera. The Crato outcrops otherwise rather yielded fossil specimens of modern mayfly families or the extinct (but modern) family Hexagenitidae. However, from the same locality the strange larvae and adults of the extinct family Mickoleitiidae (order Coxoplectoptera
Coxoplectoptera or "chimera wings" is a primitive, extinct order of winged insects containing one family, Mickoleitiidae, described by Staniczek, Bechly & Godunko in 2011...

) have been described, which represents the fossil sister group of modern mayflies, even though they had very peculiar adaptations (e.g. raptorial forelegs). The oldest mayfly inclusion in amber
Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...

 is Cretoneta zherichini (Leptophlebiidae) from Lower Cretaceous Siberian amber. In the much younger Baltic amber
Baltic amber
The Baltic region is home to the largest known deposit of amber, called Baltic amber or succinite, with about 80% of the world's known amber found there. It dates from 44 million years ago...

 numerous inclusions of several modern families of mayflies have been found (Ephemeridae, Potamanthidae, Leptophlebiidae, Ametropodidae, Siphlonuridae, Isonychiidae, Heptageniidae, and Ephemerellidae). The modern Genus Neoephemera is represented in the fossil record by the Ypresian
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between and , is preceded by the Thanetian age and is followed by the Eocene Lutetian age....

 species N. antiqua
Neoephemera antiqua
Neoephemera antiqua is an extinct species of mayfly in the family Neoephemeridae that is known from early Eocene, Ypresian stage, lake deposits near the small community of Republic in Ferry County, Washington, USA.-History and classification:...

from Washington State.

External links

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