Aeshna isoceles

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Green-eyed hawker
AeshnaIsocelesMale.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Odonata
Infraorder: Anisoptera
Family: Aeshnidae
Genus: Aeshna
Species:
A. isoceles
Binomial name
Aeshna isoceles
(Muller, 1767)
Distribution of Aeshna isoceles.png
Range of Aeshna isoceles

Aeshna isoceles (or isosceles) is a small hawker dragonfly that is found in Europe, mostly around the Mediterranean, and the lowlands of North Africa. Its common name in English is green-eyed hawker. In the United Kingdom it is a localised species, and is called the Norfolk hawker.

Contents

Aeshna isoceles is brown, with green eyes, clear wings, and a yellow triangular mark on the second abdominal segment which gave rise to its scientific name. It used to be in the genus Anaciaeschna as it different in several ways from the other members of the genus Aeshna to which it now belongs.

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 abdominal 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 Europe and around the Mediterranean and, the lowlands of North Africa. It is more common in eastern Europe than the south western Europe; it occurs in Spain and Portugal 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 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 fens 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 and north-east Suffolk. [2] It can be found in Hickling Broad and two national nature reserves: Mid-Yare NNR and Ludham - Potter Heigham NNR and at Castle Marshes in the Barnby Broad and Marshes SSSI. Since 2011 the species has also been recorded in the Stour valley in east Kent [3] 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 [4] and listed in Category 1 (endangered) in the British Red Data Books on Insects. [5]

Behaviour

Male Aeshna isoceles in flight.jpg
Male in flight
Norfolkhawker1.jpg
Female in the process of laying eggs

Aeshna isoceles is one of the earliest Aeshna 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 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 Aeshna 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.

Related Research Articles

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 Marshes and Cantley Marshes on the north bank of the Yare, and Surlingham Church Marsh on the south bank.

<span class="mw-page-title-main">Aeshnidae</span> Family of dragonflies

Aeshnidae, also called aeshnids, hawkers, or darners, is a family of dragonflies, found nearly worldwide, with more than 50 genera and over 450 species.

<i>Aeshna</i> Genus of dragonflies

Aeshna, or the mosaic darners, is a genus of dragonflies from the family Aeshnidae. Species within this genus are generally known as "hawkers" or "darners".

<span class="mw-page-title-main">Migrant hawker</span> Species of dragonfly

The migrant hawker is one of the smaller species of hawker dragonflies. It can be found away from water but for breeding it prefers still or slow-flowing water and can tolerate brackish sites. The flight period is from July to the end of October. A. mixta occurs in North Africa, southern and central Europe to the Baltic region.

<span class="mw-page-title-main">Red-veined darter</span> Species of dragonfly

The red-veined darter or nomad is a dragonfly of the genus Sympetrum.

<i>Libellula depressa</i> Species of dragonfly

Libellula depressa, the broad-bodied chaser or broad-bodied darter, is one of the most common dragonflies in Europe and central Asia. It is very distinctive with a very broad flattened abdomen, four wing patches and, in the male, the abdomen becomes pruinose blue.

<span class="mw-page-title-main">Common darter</span> Species of dragonfly

The common darter is a dragonfly of the family Libellulidae native to Eurasia. It is one of the most common dragonflies in Europe, occurring in a wide variety of water bodies, though with a preference for breeding in still water such as ponds and lakes. In the south of its range adults are on the wing all year round.

<span class="mw-page-title-main">Southern hawker</span> Species of dragonfly

The southern hawker or blue hawker is a species of hawker dragonfly.

<span class="mw-page-title-main">Hairy dragonfly</span> Genus and species of dragonfly

Brachytron is a monotypic genus of European dragonfly of the family Aeshnidae containing the hairy dragonfly, also known as the hairy hawker or spring hawker. It is found in Europe and Asia Minor, as far east as the Caspian Sea. With a typical length of around 5.5 centimetres (2.2 in) it resides close to water bodies containing plants and has a flight season running from May to July.

<i>Anaciaeschna</i> Genus of dragonflies

Anaciaeschna is a genus of dragonflies in the family Aeshnidae. Species of Anaciaeschna are found in Africa, Asia and Australia.

<span class="mw-page-title-main">Blue-spotted hawker</span> Species of dragonfly

The blue-spotted hawker is the only known species of dragonfly of the genus Adversaeschna in the family Aeshnidae.

<i>Lestes macrostigma</i> Species of damselfly

Lestes macrostigma is a species of damselfly of the family Lestidae, the spreadwings. It is known by the common name dark spreadwing. It is native to much of southern Europe, its distribution extending into western Asia.

<i>Aeshna affinis</i> Species of dragonfly

Aeshna affinis, the southern migrant hawker or blue-eyed hawker, is a dragonfly found in southern Europe and Asia. It is in the family Aeshnidae and is very similar in appearance to A. mixta.

<i>Anax parthenope</i> Species of dragonfly

Anax parthenope, the lesser emperor, is a dragonfly of the family Aeshnidae. It is found in Southern Europe, North Africa, Middle East and Asia.

<i>Chalcolestes viridis</i> Species of damselfly

Chalcolestes viridis, formerly Lestes viridis, is a damselfly of the family Lestidae. It has a metallic green body and at rest it holds its wings away from its body. Its common name is the willow emerald damselfly, the green emerald damselfly, or the western willow spreadwing. It has an elongated abdomen and pale brown spots on its wings and resides in areas of still water with overhanging trees.

<i>Ischnura intermedia</i> Species of damselfly

The Persian damselfly or Dumont's bluetail is a damselfly, belonging to the family Coenagrionidae.

<i>Epallage fatime</i> Species of damselfly

Epallage fatime, the Oriental damselfly, is a damselfly (Zygoptera) from the family of the Euphaeidae.

References

  1. Clausnitzer, V. (2018). "Aeshna isoceles". IUCN Red List of Threatened Species . 2018: e.T158692A72305432. doi: 10.2305/IUCN.UK.2018-1.RLTS.T158692A72305432.en . Retrieved 19 November 2021.
  2. "The Norfolk Hawker". British Dragonfly Society . Retrieved 15 October 2010.
  3. "Rare Dragonfly Spreading In the UK | british-dragonflies.org.uk". british-dragonflies.org.uk. Archived from the original on 2017-10-22.
  4. "Wildlife and Countryside Act 1981". Government of the United Kingdom. Archived from the original on 30 August 2009. Retrieved 15 October 2010.
  5. "The Odonata Red Data List for Great Britain" (PDF). Joint Nature Conservation Committee . Retrieved 15 October 2010.

Sources