''Rhithrogena germanica'' is a

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 orde ...

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

fly fishing Fly fishing is an angling technique that uses an ultra-lightweight lure called an artificial fly, which typically mimics small invertebrates such as flying and aquatic insects to attract and catch fish. Because the mass of the fly lure is in ...

. It is known in the

British Isles The British Isles are an archipelago in the Atlantic Ocean, 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 Hebrides, Inner and Outer Hebr ...

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

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

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 cap ...

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 Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

) by the presence of a dark spot on the femora of the legs. A similar species, '' Ecdyonurus venosus'' (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 north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...

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

Distribution

''Rhithrogena germanica'' is widespread across Central 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 ge ...

. 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 ("imaginal" being "imago" in adjective form), the stage in wh ...

collected from the

River Rhine The Rhine ( ) is one of the major rivers in Europe. The river begins in the Swiss canton of Graubünden in the southeastern Swiss Alps. It forms part of the Swiss-Liechtenstein border, then part of the Swiss-Austrian border. From Lake Const ...

at Laufenburg,

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

. Its current distribution in Switzerland only extends to a few

tributaries A tributary, or an ''affluent'', is a stream or river that flows into a larger stream ('' 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 into which the ...

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, continuing a further 35 km until it reaches the river A ...

Sihl The Sihl is a Switzerland, Swiss river that rises near the Druesberg mountain in the canton of Schwyz, and eventually flows into the Limmat in the centre of the Zürich, city of Zürich, after crossing the Zürich–Winterthur railway at . It has ...

, Thur, Töss). In the

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

River Tweed The River Tweed, or Tweed Water, 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 River Tweed. The Tweed is one of the great salmon rivers ...

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 ...

in England, the

River Wye The River Wye (; ) 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. The lower reaches of the river forms part of Wales-England bor ...

in Wales and the

River Liffey The River Liffey (Irish language, 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 Tributary, tributaries include t ...

Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...

. In

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

, it has been reported from the federal states of

Baden-Württemberg Baden-Württemberg ( ; ), commonly shortened to BW or BaWü, is a states of Germany, 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 i ...

Bavaria Bavaria, officially the Free State of Bavaria, is a States of Germany, state in the southeast of Germany. With an area of , it is the list of German states by area, largest German state by land area, comprising approximately 1/5 of the total l ...

and

Hesse Hesse or Hessen ( ), officially the State of Hesse (), is a States of Germany, state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt, which is also the country's principal financial centre. Two other major hist ...

. Further populations have been reported from

Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

Czechoslovakia Czechoslovakia ( ; Czech language, Czech and , ''Česko-Slovensko'') was a landlocked country in Central Europe, created in 1918, when it declared its independence from Austria-Hungary. In 1938, after the Munich Agreement, the Sudetenland beca ...

, and

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

; 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 (; ), sometimes also hydriads, 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 embodied ...

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 ...

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 harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

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 can ...

, 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 in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

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 a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...

and taking

flight Flight or flying is the motion (physics), motion of an Physical object, object through an atmosphere, or through the vacuum of Outer space, space, without contacting any planetary surface. This can be achieved by generating aerodynamic lift ass ...

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

trout Trout (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...

References

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