''Aeshna isoceles'' is a small hawker

dragonfly A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threate ...

that is found in

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 ...

, mostly around the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...

, and the lowlands of

North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...

. Its common name in English is green-eyed hawker. In

Britain Britain most often refers to: * The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands * Great Britain, the largest island in the United King ...

it is a rare and local species and is known as the Norfolk hawker. It has a brown colour with green eyes and clear wings and also a yellow triangular mark on the second

abdominal The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

segment which gave rise to its

scientific name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

. It used to be in the genus '' Anaciaeschna'' as it has several differences from the other members of the genus ''

Aeshna ''Aeshna'', or the mosaic darners, is a genus of dragonflies from the family Aeshnidae. Species within this genus are generally known as "hawkers" (Old World) or "darners" (New World). Description These are relatively large dragonflies. T ...

''. Its specific name is often spelt ''isosceles''.

Identification

''A. isoceles'' is one of only two brown hawkers found in Europe, the other is '' A. grandis''. Both have a brown thorax and abdomen but ''A. isoceles'' has green eyes and clear wings and a diagnostic yellow triangular mark on the second

segment. The hindwings have an amber patch at their base. In contrast ''A. grandis'' has yellowish wings and blueish eyes. The green eye of ''A. isoceles'' stands out even in flight and in practice it is not difficult to tell these two dragonflies apart. In addition to the morphological differences ''A. isoceles'' is on the wing much earlier in the year than '' A. grandis''.

Distribution and habitat

''A. isoceles'' is found in central

and around the

and, the lowlands of

. It is more common in eastern Europe than the south western Europe; it occurs in

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

and

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

but is local. It is found in wet areas, ponds, ditches and marshes, with dense vegetation and, in studies carried out in England, was found to be associated with

Water-soldier ''Stratiotes'' is a genus of submerged aquatic plant commonly known as water soldiers, described as a genus by Linnaeus in 1753. Several specific names have been coined within the genus, but at present only one is recognized: '' Stratiotes aloid ...

(''Stratiotes aloides'').

Status in Britain

The Norfolk hawker has always been a scarce and local insect in Britain. It used to be found in the

Cambridgeshire Cambridgeshire (abbreviated Cambs.) is a Counties of England, county in the East of England, bordering Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and North ...

fen A fen is a type of peat-accumulating wetland fed by mineral-rich ground or surface water. It is one of the main types of wetlands along with marshes, swamps, and bogs. Bogs and fens, both peat-forming ecosystems, are also known as mires. T ...

s but by the early 1980s the populations had greatly declined. It is now confined to relatively unpolluted fens and grazing marshes in the Broadlands of

Norfolk Norfolk () is a ceremonial and non-metropolitan county in East Anglia in England. It borders Lincolnshire to the north-west, Cambridgeshire to the west and south-west, and Suffolk to the south. Its northern and eastern boundaries are the No ...

and north-east

Suffolk Suffolk () is a ceremonial county of England in East Anglia. It borders Norfolk to the north, Cambridgeshire to the west and Essex to the south; the North Sea lies to the east. The county town is Ipswich; other important towns include Lowes ...

. It can be found in

Hickling Broad Hickling Broad is a nature reserve 4 km south-east of Stalham, north-east of Norwich in Norfolk. It is managed by the Norfolk Wildlife Trust. It is a National Nature Reserve and part of the Upper Thurne Broads and Marshes Site of Special ...

and two national nature reserves:

Mid-Yare NNR Mid-Yare NNR is a national nature reserve in Norfolk, east of Norwich, established by English Nature and managed by the Royal Society for the Protection of Birds (RSPB). The reserve is made up of four RSPB reserves: Strumpshaw Fen, Buckenham Ma ...

and

Ludham - Potter Heigham NNR Ludham - Potter Heigham Marshes is a biological Site of Special Scientific Interest north-east of Norwich in Norfolk. Part of the site is a Nature Conservation Review site, Grade I, and a National Nature Reserve. It is part of the Broadland Ram ...

and at Castle Marshes in the

Barnby Broad and Marshes Barnby Broad and Marshes is a Site of Special Scientific Interest (SSSI) in the Waveney district of the English county of Suffolk. The site is in size. It is in the parishes of North Cove and Barnby, located between Beccles and Lowestoft ...

SSSI. Since 2011 the species has also been recorded in the Stour valley in east Kent where egg laying has been observed and it appears to be spreading. It is protected under Schedule 5 of the

Wildlife and Countryside Act 1981 The Wildlife and Countryside Act 1981 is an Act of Parliament in the United Kingdom implemented to comply with European Council Directive 79/409/EEC on the conservation of wild birds. In short, the act gives protection to native species (especia ...

and listed in Category 1 (

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

) in the British Red Data Books on Insects.

Behaviour

It is one of the earliest ''

'' dragonflies to be on the wing with a flight period from May to August. Adults do not spend as much time on the wing as other ''Aeshnas''. Males will fly around over a stretch of water defending a territory and if the pond is small the male will hover over the centre of the pond. Unlike other aeshnas, where the adults seem to be continuously on the wing beating up and down their territory, male ''A. isoceles'' come to rest on vegetation from time to time. Females

oviposit The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

onto plants and the eggs hatch in about 2 weeks. Larval development takes 2 years.

Systematics

This species was first described as ''Libellula quadrifasciata, var. 36. isoceles'' by Muller in 1764. It has since been called ''Aeshna rufescens'' and ''Aeshna chysophthalmus'' and more recently ''Anaciaeschna isoceles''. It is by this last name that it is referred to in many books. It has since been included into the genus ''

'' and in many books is called ''Aeshna isoceles'': however the original specific name was ''isosceles''. Dijkstra and Lewington (2006) and Boudot JP., ''et al.'' (2009) both call it ''Aeshna isoceles'' whereas Askew, R.R. (2004),and earlier books, refer to it as ''Aeshna isosceles''.

Notes

References

* Askew, R.R. (2004) ''The Dragonflies of Europe''. (revised ed.) Harley Books. * d'Aguilar, J., Dommanget, JL., and Prechac, R. (1986) ''A field guide to the Dragonflies of Britain, Europe and North Africa''. Collins. pp336. * Boudot JP., ''et al.'' (2009) ''Atlas of the Odonata of the Mediterranean and North Africa''. ''Libellula'' Supplement 9:1-256. * Dijkstra, K-D.B & Lewington, R. (2006) ''Field Guide to the Dragonflies of Britain and Europe''. British Wildlife Publishing. . *

External links

* {{Taxonbar, from=Q1435436 Aeshnidae Dragonflies of Europe Norfolk Broads Insects described in 1767 Taxa named by Otto Friedrich Müller