Overview

Brief Summary

Biology

Larvae live partially buried in the sediment, waiting for suitable prey to pass by, which they then ambush. Their development can take as long as 2-5 years, being slower in colder waters (5). They undergo several moults during their development, which allows them to grow (3). These aggressive ambush predators feed on insect larvae, snails, tadpoles and even small fish (3).  When fully developed and metamorphosis has taken place, the larva crawls up bankside vegetation and the adult stage emerges, leaving the shed 'skin' of the larval form, known as an 'exuvia', behind on the vegetation (3). Emergence usually takes place at night in order to reduce the high risk of predation (3). Occasionally, larvae may crawl quite a distance away from the water before selecting an emergence site, and may even climb trees (2). The newly emerged adults, or 'tenerals' do not become sexually mature for around ten days (3). Like the larvae, the adults are also highly efficient and fearsome predators, feeding on large insects such as damselflies, other dragonflies, wasps, beetles and bumblebees. They are fast, agile and powerful flyers (4) and can be seen on the wing from late May to September (3). Although adult males do not defend exclusive territories, they do react aggressively towards other males that they encounter. They patrol lengths of breeding streams at just a few centimetres above the water (3). When a female is encountered the male will grab her thorax from above with his legs (2) and then manoeuvre so that the he holds her behind her head with claspers located at the tip of his abdomen. At this point the pair is said to be 'in tandem' and the male will fly with the female in this position to perch amongst vegetation, where copulation takes place (3).  Females lay their eggs alone, typically in the morning (3). The eggs are laid into the sediment of the stream, and the female hovers vertically over the water thrusting her ovipositor downwards into the sediment with a stabbing motion (5) that has been likened to the action of a pneumatic drill (3). The eggs hatch after a few weeks (3).
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Comprehensive Description

Description

The golden-ringed dragonfly is one of Britain's largest dragonflies, and is the only member of the genus Cordulegaster in the country (3). Both the thorax and abdomen are black with bright yellow bands (3), the legs are black with yellow bases (2) and the abdomen is swollen towards the tip (3). The large green eyes meet in a point at the top of the head. Females can be identified by the presence of a long pointed ovipositor at the tip of the abdomen (3). As with other dragonflies, the large wings are held outstretched when at rest, not folded back over the body as in damselflies (4). The large aquatic larva is hairy, and spends most of its life partially buried in the sediment with just the eyes and tip of the abdomen visible. The short head has prominent eyes, and in common with other dragonfly larvae it is armed with fearsome mouthparts (2).
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Distribution

Range

Common in southern, western and northern England, Wales and Scotland. It becomes rare or even absent in parts of eastern England, the Midlands, eastern Scotland and Ireland. Elsewhere this species is found in central and northern Europe (3) and extends through Asia Minor to India (4).
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Ecology

Habitat

Habitat

This dragonfly is found in heathland and moorland habitats. The larvae inhabit small streams that are typically less than 2m wide and overhung with vegetation. They are not found in still water (3).
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Cordulegaster boltonii

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Species: 1
Species With Barcodes: 1

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Conservation

Conservation Status

Status

This species is not threatened in much of its range. It is not listed under any conservation designations (3).
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Threats

Threats

This species is not threatened.
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Management

Conservation

Conservation action has not been targeted at this widespread species.
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Wikipedia

Golden-ringed Dragonfly

The Golden-ringed Dragonfly (Cordulegaster boltonii) is a large, striking dragonfly and the longest British species,[1] the only one of its genus to be found in Britain. [2]

Contents

Identification

They are easily identified by their distinctive black and yellow stripes, which no other dragonfly in Britain has. [3]

Larvae

The female lays the eggs in shallow water. The hairy larvae live at the bottom of the water and are well camouflaged amongst the silt. [4] They emerge after about 2-5 years, and usually under the cover of darkness.

Behaviour

Female Cordulegaster boltonii at rest

They are often seen flying leisurely over mountain streams or a river; they also occasional show up at a pond. They are also typically seen flying over heath land. Their bright yellow and black stripes make them easy to identify, even from a fair distance away. They feed mainly on insects ranging from small prey such as midges to flies, butterflies and even bumble bees. This strikingly-coloured insect is incredibly aerobatic and they sometimes fly very high up into the sky. [5]

See also

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