''Rhithrogena germanica'' is a

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

mayfly Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the ord ...

, and is "probably the most famous of all British mayflies", because of its use in

fly fishing Fly fishing is an angling method that uses a light-weight lure—called an artificial fly—to catch fish. The fly is cast using a fly rod, reel, and specialized weighted line. The light weight requires casting techniques significantly diffe ...

. It is known in the

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...

as the March brown mayfly, a name which is used in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

for a different species, '' Rhithrogena morrisoni''. It emerges as a

subimago Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the order ...

at the end of winter, and can be distinguished from similar species by a dark spot on the femur of each

leg A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element ca ...

Description

Adults and

s of ''Rhithrogena'' species have two long tails, and readily visible hind wings. ''R. germanica'' can only be distinguished from related species such as '' R. semicolorata'' (the only other '' Rhithrogena'' species in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

) by the presence of a dark spot on the femora of the

legs A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element ...

. A similar species, ''

Ecdyonurus venosus ''Ecdyonurus'' is a genus of mayflies of the family Heptageniidae. Species These 66 species belong to the genus ''Ecdyonurus'': * '' Ecdyonurus adjaricus'' * '' Ecdyonurus alpinus'' Hefti, Tomka & Zurwerra, 1987 * '' Ecdyonurus androsianus'' Br ...

'' (the ''late March brown'' or ''false March brown'') is more widespread in

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...

, but emerges later in the year than ''R. germanica''.

Distribution

''Rhithrogena germanica'' is widespread across

Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

and

Northern Europe The northern region of Europe has several definitions. A restrictive definition may describe Northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other g ...

. It is under threat across Europe, and

may be a stronghold for the species. ''R. germanica'' was first described by Alfred Edwin Eaton based on a single male

imago In biology, the imago (Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. It follows the f ...

collected from the

River Rhine ), Surselva, Graubünden, Switzerland , source1_coordinates= , source1_elevation = , source2 = Rein Posteriur/Hinterrhein , source2_location = Paradies Glacier, Graubünden, Switzerland , source2_coordinates= , sourc ...

at Laufenburg,

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

. Its current distribution in Switzerland only extends to a few

tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage b ...

of the Rhine (

Limmat The Limmat is a river in Switzerland. The river commences at the outfall of Lake Zurich, in the southern part of the city of Zurich. From Zurich it flows in a northwesterly direction, after 35 km reaching the river Aare. The confluenc ...

Sihl The Sihl is a Swiss river that rises near the Druesberg mountain in the canton of Schwyz, and eventually flows into the Limmat in the centre of the city of Zürich. It has a length of , including the Sihlsee reservoir, through which the river flow ...

, Thur,

Töss Töss is a district in the Swiss city of Winterthur. It is district number 4. The district comprises the quarters Schlosstal, Dättnau, Eichliacker and Rossberg. It is named after the river Töss which flows through the district. In the Middle Ag ...

). In the

, the range of ''R. germanica'' includes the

River Tweed The River Tweed, or Tweed Water ( gd, Abhainn Thuaidh, sco, Watter o Tweid, cy, Tuedd), is a river long that flows east across the Border region in Scotland and northern England. Tweed cloth derives its name from its association with the R ...

and River Don in Scotland, the

River Coquet The River Coquet runs through the county of Northumberland, England, discharging into the North Sea on the east coast at Amble. It rises in the Cheviot Hills on the border between England and Scotland, and follows a winding course across the l ...

in England, the

River Wye The River Wye (; cy, Afon Gwy ) is the Longest rivers of the United Kingdom, fourth-longest river in the UK, stretching some from its source on Plynlimon in mid Wales to the Severn estuary. For much of its length the river forms part of Wal ...

in Wales and the

River Liffey The River Liffey (Irish: ''An Life'', historically ''An Ruirthe(a)ch'') is a river in eastern Ireland that ultimately flows through the centre of Dublin to its mouth within Dublin Bay. Its major tributaries include the River Dodder, the River ...

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

. In

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

, it has been reported from the

federal states A federation (also known as a federal state) is a political entity characterized by a union of partially self-governing provinces, states, or other regions under a central federal government (federalism). In a federation, the self-governi ...

Baden-Württemberg Baden-Württemberg (; ), commonly shortened to BW or BaWü, is a German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million inhabitants across a ...

Bavaria Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...

and

Hesse Hesse (, , ) or Hessia (, ; german: Hessen ), officially the State of Hessen (german: links=no, Land Hessen), is a States of Germany, state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt. Two other major histor ...

. Further populations have been reported from

Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

Czechoslovakia , rue, Чеськословеньско, , yi, טשעכאסלאוואקיי, , common_name = Czechoslovakia , life_span = 1918–19391945–1992 , p1 = Austria-Hungary , image_p1 ...

, and

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...

; records from other areas may refer to other similar species, such as '' Rhithrogena sowai''. Rhithrogena germanica subimago on Equisetum hyemale

Life cycle

Like other mayflies, the

naiads In Greek mythology, the naiads (; grc-gre, ναϊάδες, naïádes) are a type of female spirit, or nymph, presiding over fountains, wells, springs, streams, brooks and other bodies of fresh water. They are distinct from river gods, who ...

of ''R. germanica'' are

aquatic insect Aquatic insects or water 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 c ...

s, living on the bottoms of rivers. ''R. germanica'' can tolerate a small amount of

pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

but requires high concentrations of

dissolved oxygen Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the given temperature. It ca ...

, and is therefore found in large, clean, fast-flowing rivers. The larvae of ''R. germanica'' emerge very early in the year, at the end of winter or the start of spring (March to early April). The emerging adults are vulnerable to

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s, and so their emergence is very fast; the whole process of

moulting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

and taking

flight Flight or flying is the process by which an object moves through a space without contacting any planetary surface, either within an atmosphere (i.e. air flight or aviation) or through the vacuum of outer space (i.e. spaceflight). This can be a ...

can take as little as 30 seconds. Mayflies are the only insects to have two distinct adult stages: a

, which moults into the

. ''Rhithrogena germanica'' has the longest–lasting subimago stage of any mayfly, allowing up to four days before moulting into the imago, during which time the subimago rests in a tree near the river it emerged from. Mayfly adults have no functioning mouthparts and, after reproducing, they die.

Fly fishing

The March brown is "probably the most famous of all British mayflies", having been copied by

angler Angler may refer to: * A fisherman who uses the fishing technique of angling * ''Angler'' (video game) * The angler, ''Lophius piscatorius'', a monkfish * More generally, any anglerfish in the order Lophiiformes * '' Angler: The Cheney Vice Pres ...

s to catch fish for over 500 years. It is taken by

trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salmoni ...

References

* {{Taxonbar, from=Q3429523 Mayflies Insects of Europe Insects described in 1885