Fen Bog – Yorkshire Dragonfly Group

Beautiful Demoiselle Calopteryx virgo

Posted on 26 April 2009 by Paul Ashton

Length

45-49mm; Wingspan: Male 58mm; Female 63mm; Hindwing 24-36mm; Larva: 30-35mm

Male

Dark brown-black wings, with iridescent blue veins making the wings appear metallic cobalt blue. Extreme tips and bases may be paler, there is no pterostigma. Wings are broader than the similar Banded Demoiselle. Body is metallic blue-green. Immatures wings are browner.

Female

Dark brown iridescent wings with a white ‘false pterostigma’, larger on forewing than hindwing. Wings are browner than the similar Banded Demoiselle. Body is metallic green with a bronze tip to abdomen. Homeochrome, (male coloured females) are sometimes recorded.

Behavior

Territorial males perch on bankside vegetation. They will flick their wings open and shut, occasionally chasing off passing insects, often returning to same perch. Females only visit water for egg-laying or seeking a mate, both sexes frequently stray well away from water. Flies slowly with a butterfly like flight and frequently settles on bankside vegetation or trees.

Habitat

Restricted to faster running clear water, found only along streams and rivers, often acidic, with sand or gravel bottom. Mostly found along heathland or moorland streams, though can also occur in farmland and woodland, including well shaded streams. Prefers cooler water than Banded Demoiselle. As streams broaden this species gives way to Banded Demoiselle, where there may be a broad overlap. Occasional hybridisation may take place. Sensitive to waterway management (clearance of vegetation) and pollution.

Flight Period

Status

VC61 – Only finds its way into the Vice-county due to the new course of the River Hertford being cut south of the old North and East Riding County Boundary. In many places this is within metres of the boundary.
VC62 – Extremely localised to the south-eastern area of the North Yorkshire Moors.

Distribution Map

Locations

Emerald Damselfly Lestes sponsa

Posted on 22 April 2007 by Paul Ashton

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Length

35-39mm; Wingspan: Male 42mm; Female 45mm; Hindwing 19-22mm

Male

Metallic green in colour. This species has a slow maturation period of two to four weeks, over this period a blue pruinescence appears on the thorax between wings and segments 1,2, 9 and 10. Eyes blue. Confusion species is Scarce Emerald Damselfly which is extinct in Yorkshire. Both sexes rest with wings half open.

Female

Metallic green, with pale beige sides to the thorax. Distinctly thicker abdomen than male.

Behaviour

Weak flyer usually remaining close to emergent vegetation, rarely going far over water. Copulation usually takes place close to breeding site and last from 30 minutes to over an hour. Females usually arrive to oviposit in tandem with the male. Oviposits in to stems of emergent grasses, rushes, sedges and horsetails, usually above surface, but can submerge, including the male. Fairly sedentary and can be absent from seemingly good sites.

Habitat

Still or slow moving water such as ponds, bogs, ditches, canals and lake edges with dense emergent vegetation. Tolerates brackish and acidic water. Sensitive to excessive clearance of emergent vegetation.

Flight Period

Status

Found at many sites through all Vice-counties.

Distribution Map

Locations

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Large Red Damselfly Pyrrhosoma nymphula

Posted on 22 April 2005 by Paul Ashton

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Length

33-36mm; Wingspan: Male 44mm; Female 48mm; Hindwing 19-24mm

Male

The only red damselfly in Yorkshire and unlikely to be mistaken for anything else. Red abdomen, with black bands on segments 7 to 9. Thorax is black on the top with a red stripe (yellow in immatures). Black areas have a bronze tint.

Male

Female

Occurs in three colour forms. The commonest form is typica, with black bands on most segments of the abdomen. Fulvipes is less well marked than typica and closely resembles the male. Melanotum is a dark from being mainly black, however the antehumeral stripes remain yellow (only yellow when immature in other forms).

Female – typica

Behaviour

This is the first damselfly to emerge each year in Yorkshire. It has a synchronous emergence, all emerging within a three week period, it is therefore shortly after emergence that this species is most abundant. Males emerge slightly earlier than females and also mature more quickly. Copulation lasts for around 15-20 minutes. Eggs are laid in tandem, the female may submerge taking the male with her. The life cycle is two years, on initially occupying a new site there may therefore only be adults found every other year.

Habitat

Has a wide habitat tolerance, including brackish and slightly polluted water, though avoids fast flowing water. Higher abundance in well vegetated, standing water.

Flight Period

Status

Evenly distributed across VC61-64, scarcer in VC65.

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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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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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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Emperor Dragonfly Anax imperator

Posted on 22 April 1992 by Paul Ashton

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Length

78mm Wings, 106mm.

Males

Thorax bright green; abdomen blue with black central line; legs black; eyes green; wings clear with yellow costa.

Females

Generally greenish with thicker black central abdominal line.

Habitat

Ponds, lakes, gravel pits, dykes, canals and slow-flowing rivers with rich marginal vegetation, also tolerant of brackish conditions. Seldom found far away from water.

Behavior

Males are territorial, rarely more than one male is present at small locations. Constantly patrols its territory, which it defends vigorously. Will take prey as large as Four-spotted Chaser Libellula quadrimaculata. Copulation takes place away from water and lasts around ten minutes. The female then oviposits alone into submerged vegetation. Larvae emerge after two years on to tall emergent vegetation. Emergence is usually synchronous at site level.

Flight Period

Distribution Map

Locations

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Golden-ringed Dragonfly Cordulegaster boltonii

Posted on 22 April 1988 by Paul Ashton

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Male

Length 74mm, wings 100mm.

Predominantley black species, with yellow thoracic stripes and antehumeral stripes on the thorax, with yellow rings around the abdomen, slightly swollen towards the tip. Green eyes. Female Southern Hawkers sometimes confused with this species.

Female

Length 84mm, wings 100mm.

Predominantley black species, with yellow thoracic stripes and antehumeral stripes on the thorax, with yellow rings around the parallel sided abdomen, ovipositor extending beyond segment 10. Green eyes. Female Southern Hawkers sometimes confused with this species.

Both

Black with yellow markings, as rings on abdomen; eyes greenish; legs black; female has sharp ovipositor; wings clear with leading edges (costa) yellow.

Habitat

Streams and rivers with silt, gravel or stone base in upland areas or lowland heath.

Behavior

Eggs laid in bed of stream, etc. Larvae 2-5 years.

Flight Period

Distribution Map

Locations

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Four-spotted Chaser Libellula quadrimaculata

Posted on 22 April 1986 by Paul Ashton

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Length

43mm, Wings 76mm

Males

Thorax brown, no antehumeral stripes; abdomen brown, last 4 segments darker than the rest, yellow spots on sides; wings dark patches at nodes on leading edges and at bases of rear wings.

Females

Similar to males, main difference is the shape of the anal appendages.

Habitat

Prefers sites of still water consisting of lakes, ponds, bog pools, canals and dykes. Will tolerate brackish conditions. The largest concentrations are associated with acidic ponds and pools.

Behavior

Males are territorial, their noisy clashes are obvious where densities are high. Readily returns to the same perch on emergent vegetation, after sparring with other males, or after short patrols along the waters edge. Copulation is short taking place in flight, only lasting for 5-20 seconds. Female oviposits by flicking the abdomen tip downwards into the water. The eggs then sink and adhere to submerged vegetation. Males may stay close by to guard females during oviposition. Larvae live among the bottom debris, then emerge after two to four years. Emergence takes place amongst marginal vegetation during daylight hours.

Flight Period

Distribution Map

Locations

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