Species – Page 2 – Yorkshire Dragonfly Group

Small Red-eyed Damselfly Erythromma viridulum

Posted on 22 April 2003 by Paul Ashton

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Length

29mm; Wingspan: Male 38mm; Female 38mm; Hindwing 16-20mm

Male

Similar to Red-eyed Damselfly though distinctly smaller, more likely to be overlooked as Blue-tailed Damselfly. Lacks spots behind the eyes which are reddish-brown. Pale brown pterostigma. Black top to thorax with thin, broken antehumeral stripes. Thorax side is blue with a ‘Spur’ often ending in a spot. Underside of legs are pale. Abdomen dark on top except for S1, S9- S10 and sides of S2-S3 and S8 which are blue. S10 has a black mark, rather like an X, on the top. Wing tips just reach past the join of segment 6 and 7, Red-eyed Damselflies reach into segment 8. Often holds it’s abdomen slightly upcurved, Red-eyed Damselflies hold their abdomen level.

Female

Lack spots behind the eyes. Pale brown pterostigma. Black top to thorax with complete antehumeral stripes. Thorax side is blue-green. Abdomen is predominantly black with a wedge of colour on S10.

Behaviour

During the day males appear constantly active, patrolling well away from the margin in search of females. Once copulation has taken place, they oviposit in tandem into stems and leaves of floating vegetation. They can often submerge for long periods of time. Larvae live among submerged water plants and emerge after one year on to floating vegetation.

Habitat

Ponds, lakes and ditches with plenty of floating vegetation such as Hornwort Ceratophyllum, Water-milfoil Myriophyllum and Waterweed Elodea. Also uses rafts of floating algae. Generally found in sheltered positions, with nearby trees and shrubs for roosting. Will tolerate brackish conditions.

Flight Period

Distribution Map

Locations

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Blue-tailed Damselfly Ischnura elegans

Posted on 22 April 2002 by Paul Ashton

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Length

29-34mm; Wingspan: 35-40mm; Hindwing 14-21mm

Male

Dark bronze-black metallic with blue segment 8. Blue or green sides to the thorax and antehumeral stripes. Blue eye spots. Pterostigma is distinctive being bi-coloured black and white. Tips of the lower appendages diverge.

Female

Occur in several colour forms dependent on age. Segment 8, though not always blue, is usually clearly different from the other sections. Start as either rufescens with a reddish-pink thorax and blue segment 8 or violacea with a violet thorax and antehumeral stripes, black humeral stripes and blue segment 8. After around eight days they mature and change colour, rufescens become greenish-brown of the form rufescens-obsoleta. The form violacea mature into two separate from. The first is infuscans which is a pale green colour, and retaining the black humeral stripes. The second is an andromorph form which adopts the same colours as a male.

Behavior

Often found in marginal vegetation in large numbers. Copulation last from between two to six hours, due to this, it is the most frequently observed species seen in the wheel position. Often females selected by the males are still in their immature colour forms. Females oviposit alone onto the tissue of aquatic plants and debris, where they are not usually harassed by the males. Frequently found in dull weather when other species are inactive. Larvae emerge after one to two years.

Habitat

Wide range including garden ponds, lakes, rivers, canals and ditches. Can also be found in brackish conditions and acidic peaty pools. More tolerant of pollution than other species, only really avoiding fast-flowing water. Readily disperses and is one of the first species to colonise new sites.

Flight Period

Status

Common and widespread throughout the area.

Distribution Map

Locations

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Azure Damselfly Coenagrion puella

Posted on 22 April 2001 by Paul Ashton

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Length

33mm, Wings 36-44mm

Males

Bright blue body with black markings; thorax black top with 2 thin antehumeral stripes; abdomen black U-shaped mark segment 2, segment 8 blue and 9 marked black; eyes bright spots not joined by a bar.

Females

2 colour forms:-
1) Body green with black markings on upper surface; segment 2 with black thistle shape.
2) Blue form has “mercury” shape on segment 2; rest of black upper markings are more extensive; narrow pale antehumeral stripes.

Note: The shape of the pronotum is the only conclusive way to seperate this species from Variable Damselfly. Personal observations have highlighted that female Azure Damselflies lack the bar between the eye spots, compared to Variable Damselfly.

Comments

Initially this species is more abundant than the similar Common Blue Damselfly with which it can be easily confused. It is easy to make the mistake of identifying early blue damselflies as being Azure, then assuming on later visits that this is still the case. However after four of five weeks, Azure can suddenly become harder to find as Common Blue Damselfly become more abundant.

Habitat

Wide range of habitats from garden ponds, lakes, ditches, streams, canals and rivers to peaty pools. The main requirement is plenty of marginal vegetation in sheltered locations. Frequently settles on floating vegetation, as well as being readily found in adjacent grasslands and sheltered woodland edges.

Behavior

Not territorial. Copulation is prolonged on warm sunny days. Pairs oviposit in tandem into soft plant tissue, often submerging to do so. Larvae live among submerged vegetation and emerge after one year. Emergence takes place on marginal vegetation or flower spikes in the centre of water bodies. Females emerge first, followed a few days later by the males.

Flight Period

Status

Common

Distribution Map

Locations

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Variable Damselfly Coenagrion pulchellum

Posted on 22 April 2000 by Paul Ashton

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Length

23-30mm; Wingspan: Male 42mm; Female 42mm; Hindwing 16-23mm

Male

Coenagrion Spur’ on side of thorax, also present on Azure Damselfly, but absent on Common Blue Damselfly. Antehumeral stripes are usually broken, sometimes they can be absent or complete. Wine glass marking on segment two of the abdomen. Segment nine contains a square with three points (three pointed crown). Overall appears more slender and darker than the similar Azure Damselfly. Can be confirmed by the strongly trilobate margins of the pronotum.

Female

‘Coenagrion Spur’ on side of thorax, also present on Azure Damselfly, but absent on Common Blue Damselfly. Antehumeral stripes are usually complete. Black thistle shape on segment two. Blue form, blue on top of the abdomen. Dark form, similar to Azure Damselfly is not as numerous. Overall appears bluer than the similar Azure Damselfly.

Note: The shape of the pronotum is the only conclusive way to seperate this species from Azure Damselfly. Personal observations have highlighted that female Variable Damselflies have a bar between the eye spots, which is absent in Azure Damselfly.

Behaviour

Males are none territorial. Copulation last around 10-15 minutes. Once copulation has taken place the pair will oviposit in tandem, into stems of floating water plants, or remains of rushes and common reed. The larvae develop in one year living among submerged vegetation.

Habitat

Fens, ponds, lakes, slow-flowing dykes, canals and peaty pools. Dependant on plenty of emergent vegetation. After emergence, tenerals require sheltered areas to mature, often being found in adjacent grasslands and in the lee of shrubbery and hedgerows.

Flight Period

Status

After a tentative report in 2006, now confirmed as being present in East Yorkshire. Currently restricted to the Broomfleet Washlands complex. This is currently the only species present in Yorkshire that is of national importance due to its near threatened status.

Distribution Map

Locations

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Common Blue Damselfly Enallagma cyathigerum

Posted on 22 April 1999 by Paul Ashton

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Length

32mm, Wings 36-42mm

Male

Bright blue body with black markings on upper surface of abdomen, segment 2 has lollipop mark; segment 8 and 9 all blue; broad antehumeral stripes on black thorax; eye spot linked by bar.

Female

3 colour forms:-
1) abdomen with black markings.
2) Green with black markings.
3) Brown with black markings. All have characteristic medial spine under segment 8, presumably puncturing plant material before inserting an egg.

Habitat

Large ponds and lakes are the main preference for this species. Can also be found along canals and rivers, but will also tolerate brackish conditions. The most abundant Zygoptera found in open areas.

Behavior

The most dominant species on large lakes and reservoirs, swarming over the waters surface far from the banks in sunny conditions. Readily settles on emergent vegetation and is aggressive towards others, even driving away larger species. Copulation lasts for around 20 minutes, frequently away from water. Oviposits into submerged and emergent vegetation, usually in tandem. If the female submerges the male will uncouple, guarding the area waiting for her to re-emerge. Females can submerge for up to an hour. Larvae live amongst submerged vegetation emerging after 1-3 years. They mature in surrounding areas over a period of around 12 days.

Flight Period

Status

Occurs on a wide range of varying water-bodies. Can be more conspicuous than the similar Azure Damselfly. Blue damselflies ranging far over open water are usually this species. Generally the most abundant blue damselfly at sites, where the Azure can be absent.

Distribution Map

Locations

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Common Hawker Aeshna juncea

Posted on 22 April 1997 by Paul Ashton

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Length

74mm, Wings 95mm.

Males

Thorax top is black , narrow yellow antehumeral stripes and sides are brown with 2 narrow yellow thoracic stripes; abdomen black with pairs of yellow and blue spots including segments 9 and 10; legs black; wings have brilliant yellow costa.

Females

Thorax brown; abdomen brown with paired yellow spots, sometimes green, rarely blue. Leading edge of the wing yellow.

Habitat

Prefers acidic conditions, consisting of bog pools, ponds and lake margins on moorland and heathland. Will also use slow-flowing sections of upland streams. Requires areas of emergent vegetation to breed.

Behavior

Males are territorial, regularly chasing off intruders of any species. They are relentless flyers and can often be found active in dull conditions. Copulation takes from 60-75 minutes, with pairs usually settling amongst the heather, shrubs or trees. The female oviposits alone, inserting the eggs into submerged vegetation. Oviposition may take place in dull weather, when the first sign of activity is the sound of rustling wings in low vegetation. Larvae develop over a period of two or more years amongst the submerged vegetation. They emerge, usually at night, on emergent plant stems. They regularly wander away from breeding sites to feed in sheltered areas, such as woodland rides.

Flight Period

Distribution Map

Locations

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Migrant Hawker Aeshna mixta

Posted on 22 April 1996 by Paul Ashton

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Length

63mm, Wings 87mm

Males

Thorax brown with broad thoracic stripes, with short indistinct antehumeral stripes; abdomen brown, yellow triangle mark on segment 2, separate pairs of blue spots along rest of abdomen; legs brown; eyes bluish; wings have brown costa.

Females

Thorax antehumeral stripes very restricted, often missing; abdomen brown with small yellow-brown spots; long anal appendages. Brown costa, leading edge to the wing.

Habitat

Still or slow-flowing waters including ponds, lakes, sand and gravel pits, reservoirs, slow-flowing rivers, canals and ditches. Will tolerate brackish conditions, though avoids acidic water.

Behavior

None territorial and often present in high densities with little sign of aggression. Frequently hovers, searching for females in marginal vegetation. Both sexes can be found well away from water in sheltered locations, such as woodland rides and hedgerows. Regularly found perched in the open. Copulation is lengthy and once complete, the female will oviposit alone. Oviposition usually occurs into emergent plants above the water, though occasionally in bare mud. Emergence usually occurs the following year, often during the night. Despite being abundant late in the season, few exuviae have been found. Those that have been recovered are usually found low down in thick vegetation. Due to the lack of breeding data, it would suggest that the majority of adults observed are migratory individuals.

Flight Period

Distribution Map

Locations

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Southern Hawker Aeshna cyanea

Posted on 22 April 1995 by Paul Ashton

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Length

70mm, Wings 98mm.

Males

Thorax – green and brown with broad green antehumeral stripes; abdomen – yellow triangle segment 2, green spots segments 3-8; undivided blue spots segments 9-10; wings brownish tinge; legs brown-black.

Females

Thorax – green and brown with broad green antehumeral stripes; abdomen brown with green spots, undivided green spots on segments 9-10.

Habitat

Lakes and ponds, including small garden ponds where it is the most likely Aeshnidae to be encountered. Also found along canals and ditches. Will feed away from breeding sites, sometimes being encountered in sheltered areas, such as woodland rides and hedgerows.

Behavior

Males are territorial, with a single male usually found at a small pond. There is however a constant change of males throughout the day. This is an inquisitive species, often approaching close to the observer. They can be active in dull weather, often on the wing late into the evening, even hunting when it is raining. Copulation takes place away from water, lasting for around two hours. The female oviposits into waterside vegetation, moss or bare soil above water, often in poor weather. Larvae emerge after two to three years on tall marginal vegetation. They mature away from water over a four to six week period, before returning to suitable sites to breed.

Flight Period

Distribution Map

Locations

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Brown Hawker Aeshna grandis

Posted on 22 April 1994 by Paul Ashton

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Length

73mm, Wings 102mm.

Males

Thorax brown; abdomen brown with bright blue spots at sides; wings characteristically honey brown colour; legs pale brown.

Females

As males except blue spots on abdomen replaced with yellow markings.

Habitat

Lakes, ponds, gravel pits, canals, ditches and slow-flowing rivers. Will tolerate moderate levels of pollution.

Behavior

Males are territorial, even defending territories away from water. They are often observed hawking along woodland rides and hedgerows. This is a difficult species to approach when settled, the first sign of their presence is usually the rustling of wings, as the fly up from roosting places in tall grasses. Copulation is lengthy, the female then ovipositing into emergent floating vegetation, or decaying floating logs, where several females may oviposit together. Larvae emerge two to four years later at night, with the maiden flight taking place before dawn.

Flight Period

Distribution Map

Locations

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Norfolk Hawker Aeshna isosceles

Posted on 22 April 1994 by Paul Ashton

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A rare vagrant, with only three records; two from Spurn and one from Wykeham Lakes.

Flight Period

Distribution Map

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