High Fashion and Green Metal in an Essex Summer: The Lestidae Damselflies

 As it is (ed: Not long past) Christmas, and I have already written of a decidedly Christmassy species, I thought, in the dark of St Stephen’s Night, to revisit the insects with which I spent a privileged summer, through the coastal marshes of Essex. The Lestidae damselflies, or Emerald Damselflies, come in a range of shades from key lime pie green, to metallic fir tree tinsel green, some bearing a dusty blue pruinescence. They are desperately fashionable too, subject of many treatises, management plans and UK Wildlife Podcasts, in part because of their undoubted beauty, more subtle than that of the splendid Calopteryx spp - perhaps more of them later- and less easily spotted than the big Aeshnids I wrote about before. Essex is their spiritual home- and arguably one of the epicentres of their remarkable colonisation of these islands. All four breeding species are found in the county, and I had the privilege of meeting them all over the summer of 2022.

Scarce Emerald Damselfly nomming a Blue Tailed Damselfly (Ishnura elegans)

Willow Emerald Damselfy, RSPB Bowers' Marsh, Essex. 

My first encounter with these splendid creatures was a couple of years ago at RSPB Rainham Marshes, where I met a gorgeous, deep bronze green insect hanging serenely on some wetland tree that may or may not have been the one from which it took its common name. This slim and delicate creature was a Willow Emerald (Chalcolestes viridis) a stunning creature which immediately caught my eye, especially as it was October, when all but the hardiest Common Darters and Migrant Hawkers had reached the end of their season. The Willow Emerald is unique among British odonata as it does not lay its eggs in water, but instead, in neat incisions made in woody vegetation overhanging water with a modified ovipositor. I have witnessed them laying eggs like this while still in tandem, the male gripping the female with his anal claspers, protecting, or jealously guarding her. From these eggs the tiny prolarvae emerge in spring, and drop into the water below to continue their life cycle, much more typically. Any which fail to find water do not make it, but conversely, being to an extent free of the need for water during late summer oviposition offers an advantage in a drying climate.  This species was first recorded breeding in the UK in something like 2009, in Suffolk. On a September walk by the Thames at Tilbury in 2022, with my good friend Chris, we found hundreds of these beautiful, bronze green insects, hanging out on Brambles tens of metres from fresh water. It is a species which has undergone a meteoric rise. Look for an all-green Damselfly, sometimes shimmering bronze in the sunshine as the light catches its iridescence, with clear wings (mind those flashy Calopteryx!) white pterostigmas (the dots in the ‘outboard’ corners of the wings), hanging out on marginal woody vegetation near still or slow-moving water.

Willow Emerald, Tilbury, September 2022

A few years later, while walking among the ditches at an EWT nature reserve way off the beaten track yet not too far from Basildon. Hanging on a branch, apparently relatively freshly emerged, was a beautiful male Scarce Emerald (Lestes dryas). Contrary to its English name, this species seemed very numerous on the sites where it lived. A hulking brute of a damselfly, size being a key if not universally reliable way of separating it from the smaller Emerald Damselfly (Lestes sponsa), and another species identified as having a distinct upward population trend, it likes Sea Clubrush choked ditches, sometimes to the consternation of site managers irked by its insistence on enjoying exactly the habitats wading birds do not, and often co-occurs on the coastal grazing marshes also favoured by Small-Red Eyed Damselflies and Ruddy Darter Damselflies. Like all Odonata it is an active predator, adult and nymph, largely taking small flies,  but not averse to dining on its distant relatives. At RSPB Old Hall, what I initially took to be a mating pair of Blue-Tailed Damselflies, turned out on closer inspection to be a Scarce Emerald feasting on the corpse of a Blue-Tailed Damselfly. In addition to an impressive display of predation, though I had no way of telling whether the Emerald had caught its prey on the wing or simply made a fortuitously (for the Emerald) timed landing, it represented a good chance to compare the blue bits of the two species. The steel blue pruinescence, a dusting of scales which fades with age, contrasted strongly with the almost luminescent looking blue tail-light of the commoner species.  Scan through the big crowds of Blue Tailed Damselflies for this big beast, and use your close-focus bins or a good photo to identify it by the pruinescence covering the whole of the first two segments of the abdomen, and the big, bent-paddle claspers at the back end to separate from male Lestes sponsa. A slightly different pattern of green and pale cream on the thorax separates the females of these species.  Look for them in June and July, I saw few of them after the big heatwave of 2022, for reasons unknown, perhaps it baked off the adults or desiccated any late developing nymphs.

Scarce Emerald (female) Essex 2022

Scarce Emerald (Male) Essex 2022

Historically, the commonest of the Lestidae in the British Isles, and still the one you’re most likely to encounter outside of South Eastern England, is Lestes sponsa, the Emerald Damselfly, you may hear it called the Common Emerald Damselfly.   This species has undergone something of a decline of late, like many of our odonata, as documented in the State of Britain’s Dragonflies report. It is hard to separate from L. dryas, I recommend a good book with the illustrations of Richard Lewington in it and a good pair of low-magnifying small binoculars for close focus, though any particularly small Lestes-with-blue-bits is likely to be one. Sadly I encountered just a few of this species during my summer transects.

Emerald Damselfly, Essex, 2022

The fourth species is the newest, and perhaps the slowest colonising, the beautiful and distinctive looking Southern Emerald Damselfly (Lestes barbarus). This is a gorgeous, key lime pie of an insect, with its dark green metallic upper surfaces contrasting with the pale, green-tinged yellow of its undersides, boasting a unique and instantly recognisable (yes, really) bicolour pterostigma, half milk white, half blackish brown. It has distinct ‘antehumeral stripes,’ look for markings like braces on its thorax. Its stronghold is on Canvey Island, of all places, I am advised a particular ditch is a good place to look, but I found it on the site near Basildon, where it was a new record. More delicate looking than the other three, it was first recorded in Britain in 2002, in Norfolk, and it’s been gradually colonising low-lying Essex since being discovered at Wat Tyler Country Park by Neil Phillips in July 2010, with other early records coming from Gunners Park, Shoeburyness in 2012. It is a more committed climate change rebel, and habitat specialist, than even the Willow Emerald, relying on ditches drying up in late summer for oviposition. I could scarce believe my eyes when I found one near Basildon on an EWT reserve. These species are moving so fast and unpredictably with their quiet invasion that they are one group in which the observations of keen eyed amateur naturalists and local surveyors can make real changes to known distribution maps.

Southern Emerald Damselfly, EWT site, Essex. 

So think of them on these winter days, and dream of them shimmering beneath a warm summer sky. Their season will roll around soon enough. Get yourself a good dragonfly book, a good pair of bins, and, come June, go to your favourite wetlands. You may just find yourself a new favourite insect there.

Southern Emerald Damselfly

*This blog has been edited since posting to correct the timeline of Southern Emerald colonisation and credit the finder. 

The Darter Dragonflies

As I write, it is grey outside. Mild now the now has melted, but drizzling and chill. Dragonfly season is well over. But it lasted into October, even November with the mild conditions and today feels an excellent day to look back.

Ruddy Darter, male, Essex 2022

At nearly every site I surveyed, the most numerous genus of Dragonfly I encountered, especially as the season pushed on into August and September, was Sympetrum. Specifically, Sympetrum sanguineum, the Ruddy Darter, and S. striolatum, the Common Darter, the former apparently capable of surviving even mildly brackish water conditions, favouring low lying coastal marshland, occurring alongside Scarce Emerald Damselfly (Lestes dryas) and Southern Migrant Hawker (Aeshna affinis). The latter, S. striolatum, is capable of flying well into the season of mists and mellow fruitfulness and is often one of the last dragonflies on the wing. However despite their abundance, and their abundant charisma, this genus seems relatively unexplored in the popular literature.

Ruddy Darter, Male, in Obelisk position as he attempts to lose heat during the heatwave of July 2022. 

These represent the two commonest species of Sympetrum, a genus in the family Libellulidae. Both species are broadly speaking red in the adult male, and gold, fading to brown in the the females. These creatures are, like other Odonata, agile aerial predators as adults, darting from their perches and sunbathing spots to seize small insects off the wing. It is this darting habit which gives them their common name. Their larvae lurk in almost any still or slow-moving body of water you might find.

Common Darter, Rainham Marshes, October 2021

Most numerous in the low coastal marshes of Essex in June and July is the Ruddy Darter (Sympetrum sanguineum),the males vivid, blood-red as the scientific name implies, the females an eye catching straw gold. They are the smallest of the ‘large’ dragonflies (Anisoptera) typically on the wing. They tend to form an assemblage with Scarce Emerald Damselflies (Lestes dryas) and Southern Migrant Hawkers (Aeshna affinis) alongside several of the small, blue damselflies, a habit noted by Brooks and Cham in their excellent field guide, which I found reflected strongly when I had the privilege of carrying out dragonfly surveys for a conservation organisation in the Summer of 2022. The males possess something of a ‘waist’ to the abdomen and can appear club tailed. Legs are jet black and the thorax lacks distinct stripes.

Common Darter, Otmoor, Oxfordshire, September 2022

Common Darter Breeding territories are closely guarded, with adults prepared to chase away any intruders, but away from water, their habitats are different. They like to be in the sun, and pick the sunniest spot they can find, and bathe in it, absorbing the solar energy through their skin. Signage, gateposts and fencing are among their favoured perches, and here they can gather in large numbers, occasionally lifting up, briefly, to grab some passing prey on the wing, or in readiness to flee a threatening shadow, before settling back down again, usually in the same patch of sunshine from which they took off. In Autumn especially, Common Darters can be surprisingly willing to come and sit on an outstretched hand, something I have witnessed and done several times, at a few sites up and down the country. Try it one sunny afternoon. Go somewhere with abundant Common Darters, any still water with adjacent sunlit rides is a good bet, find a patch of sunshine, and hold out a hand.Perhaps these engaging insects will come and visit. Stand calmly; they are completely harmless and will not bite, and they will use you as a sunbathing and bug hunting post.

Black Darter, male, Garry, Isle of Lewis and Harris, Scotland, August 2021

Both Common and Ruddy Darter are abundant and thriving, but another Sympetrum, S. danae, the Black Darter, a specialist of acidic pools on heath and moorland, has shown significant declines in its numbers in recent years. It is still an abundant dragonfly in the somewhat specialised habitats in which it occurs. Our smallest Sympetrum, and indeed our smallest true Dragonfly, shorter than your little finger, the male S. danae is also the only entirely black dragonfly in Britain; the female is black and gold. Like their red lowland cousins they can be confiding and will occasionally perch on fingers. Another upland species, under more extreme threat of local extinction, is the White-Faced Darter (Leucorrhinia dubia), reintroduced since 2010 to Foulshaw Moss in Cumbria, a Cumbria Wildlife Trust reserve probably most famous for its breeding Ospreys. A true specialist, this beautiful insect, with a white frons and a body dappled red and black, or gold and black in the female, they spend their larval development right down among the mass of sphagnum, avoiding open water, or anywhere fish can be found. Like so many species of the North, it is threatened by peat extraction, the abandonment of traditional moorland management, and by a warming climate. The peatland habitats in which these two darters dwell represent an important carbon sink, ever growing Sphagnum, is a real asset in our fight against man-made climate change. Efforts to secure the future of these two little dragons in Britain are efforts to secure the future of our world and ourselves.

White Faced Darter, female, Foulshaw Moss, Cumbria, May 2015

So keep an eye, next summer and into the Autumn, for these species wherever you happen to wander. The two ‘red’ species so numerous here in Essex are common and widespread, flying from May into late October, even November. They are sometimes overlooked in favour of the more glamourous Aeshnids and distinctly fashionable Lestidae damselflies, but I think they have a remarkable charisma of their own.

The Aeshnid Dragonflies

 

I love Aeshnid Dragonflies. It was a love affair that probably began at Dungeness in 2010, when the big Aeshna mixta, Migrant Hawker dragonflies, provided me with excellent photography subjects and generally kept me entertained between counting passerines when I was doing my Undergraduate dissertation. I wondered at the speed at which they could climb and dive and turn, more than matching a Helicopter or a Swallow for aerial agility. I watched their hunting flights, the speed at which they could bring down insect prey small and large (ish), and how relaxed and complacent they would become when they perched up to eat and digest. I love the jewel markings like inset sapphires in their long, knitting-needle abdomens. I love their huge, wrap around compound eyes, affording a wide field of vision to spot prey and predator alike.

Aeshna juncea nomming a Speckled wood Butterfly. Isle of Mull, June 2014

These big insects are predators and no mistake. During their few short weeks on the wing they grab prey up to the size of large butterflies off the wing, and I have seen a Common Hawker (Aeshna juncea) eating a Speckled Wood Butterfly on a sunny June day on the Isle of Mull, completely unbothered by me and my camera lens, fixated on dismantling and hungrily devouring the smaller insect. They are hunters in their youth, too. A. juncea can spend a couple of years as a larva, in the small ponds in which it lives, hunting even small vertebrates like tadpoles and froglets, a veritable tiger among the pondweed. They can live at considerable latitudes, their growth limited by the low temperatures, while cogeners in Southern Europe can have several broods a year.  A. juncea is sometimes called the Moorland Hawker, for the Northern and Upland habitats in which it can thrive.

Migrant Hawker, Otmoor, Oxfordshire, August 2022

Aeshnids in the British Isles come in two genera, Aeshna, a name which Wikipedia claims might originate from a misprint, Aechma being ancient Greek for Spear, presumably in reference to their elongated shape and predatory nature, and Anax, from the ancient Greek for a king or leader, the emperor dragonflies. Both these genera are widely distributed around the globe. They are members of the order Odonata, infraorder Anisoptera, and now thought only distantly related to the similar, huge insects of Carboniferous palaeontology, though in the air they do appear true heirs to these prehistoric monsters. In adulthood all are predatory, and most are territorial, individuals patrolling stretches of hedgerow or pond side and tolerating no insect intruders.  Their larvae, called Nymphs, are, like other odonata, ambush predators, lurking in the pondweed and snatching passing water life. As large insects, they can take multiple years to mature.

Female Migrant Hawker, Essex, August 2022

In the Autumn, our most numerous Aeshnid here in Southern England is the Migrant Hawker (Aeshna mixta) which can be found, sometimes forming large groups of individuals, terrorising the little midges and such which gather in glades and on open rides, sometimes far from the water in which they started their lives. These groups can reach some numbers, and, unusually for dragonflies, they can be surprisingly tolerant of each other, seldom engaging in the high pursuit, rolling, dangerous territorial fights which seem to occupy a lot of time for other species. The Migrant Hawker only spends one year as a larva, emerging in late summer and early Autumn and remaining on the wing until mid-November where we are now.  It’s first segment is identified by a ‘golf-tee’ shaped marking. Sometimes a larger Southern Hawker (Aeshna cyanea) appears, and menaces them. This beast, which once bred in our Essex garden pond, is substantially larger than the migrant hawker, and tolerates few rivals. Its abdomen is jewelled in Blue and Green.

Elderly Migrant Hawker being 'mobbed' by a Willow Emerald Damselfly. RSPB Rainham Marshes, Essex, October 2021

More recently, Southern England, and my home county of Essex in particular, has become a hotspot for a new Aeshnid. The Southern Migrant Hawker (Aeshna affinis) is increasingly common on the ditches and grazing marshes which line the Essex coast from the Thames to the Stour. This beauty has a thorax washed with blue over a base of green, and a vivid blue abdomen. Its segment one is marked with a ‘Deadpool mask’ marking, recalling the face of Marvel’s sweary superhero.  First identified in the county in 2007, my summer was full of these stunners, fighting and breeding over clubrush and reed lined ponds and ditches in July and August. By my understanding, how long the Essex population spends as a larva remains unclear, though it is probably one year, and this incredibly handsome invertebrate is one of climate change’s winners, locally at least, benefitting from the hotter summers.

Southern Migrant Hawker, Bower's Marsh, Essex, July 2022

In contrast, Brown and Norfolk Hawkers are relatively dull in colour, large and robust, the Brown Hawker (Aeshna grandis) having brown flushed wings, and the Norfolk Hawker (Aeshna isosceles), now found much more widely in the UK than confined to Norfolk, though still considered rare and localised. The Norfolk Hawker has big, green eyes, and is relatively widespread in Continental Europe and North Africa. The Brown, which is large, has two pale diagonal stripes on its thorax and subtle blue eyes. It too is doing well, expanding its British range.

Emperor Dragonfly, male, Bowers' Marsh, Essex, July 2022

Though recently the Lesser Emperor (Anax parthenope) has been confirmed breeding in Southern England, for a long time the only Anax dragonfly in these islands has been the spectacular Emperor Dragonfly (A. imperator). This big, green and blue Dragon, by some measures the largest species in Britain, is common and familiar. I have witnessed them ovipositing in borrowdykes on the Essex marshes, and in city centre park ponds. The male has a solid, muted green thorax and a bright blue abdomen, distinctive by their size. They fly in high summer, into August, and range across much of the country.  

Southern Migrant Hawker, Essex, August 2022

Aeshnids form a most impressive family of insects.  Predators, aerobats extraordinaire, survivors and thrivers, wonders and jewelled terrors of freshwater bodies and their environs, nymph and adult. And even in November, it is not too late to see the distinctive shape of a Migrant Hawker, patrolling the hedgelines near you.

Dartford Warblers at Arne

Dartford Warblers

Dartford Warblers (Sylvia undata) are among the scarcest and most enigmatic passerines to grace these islands, and surely among the most charming. When vast tracts of heathland covered much of Southern England, the species was not uncommon, and it is named for Dartford Heath in North Kent, from which it has been absent for decades.  Perhaps more at home in Mediterranean Europe, it is on the edge of its range in Great Britain. With the increasing development and fragmentation of this habitat, sitting as it does in desirable Surrey and Dorset, it underwent decades of decline.  It is also said to be particularly vulnerable to predation by domestic cats, which can exclude it from small scraps of habitat saved from housing developments. An exclusive insectivore, and largely sedentary species, its greatest enemy is the British winter, persistent snow can wipe a colony out, and a cold winter in the early 1960s nearly did for the British population entirely, just a few pairs appearing after the snow finally melted.  However, amid great conservation effort and with possibly a small helping hand from climate change, the species is beginning to recover. 

Dartford Warbler at Arne.

There are a few places where these birds can reliably be found. Arne, and surrounding fragments of heath, and Chobham Common in Surrey, where I first met the species, host good numbers year round. They are vulnerable to disturbance, and responsible birders do not go tramping through the heather at any time of year. Occasionally individuals turn up on the coast in Southern England, undertaking short movements to avoid the very worst of the weather.

A view from Arne.

It was at the RSPB’s magnificent pristine heathland reserve at Arne, near Wareham in Dorset, that I had my most recent, and most magical encounter with these gorgeous little passerines. A solo expedition to one of my favourite corners of the country in the hope of catching up with Nightjar (I did, but not enough to blog about), I camped near this magnificent spot, a large tract of Dorset coastal heath on Poole Harbour overlooking Brownsea Island, managed impeccably for conservation, and took a long stroll among its heathland rides.  Arne was abuzz with dragonflies and butterflies and hoverflies, and 90 common spotted orchids grew along the bank of one small pond which must have hosted half a dozen different Odonata, including an iridescent Downy Emerald and a striking pair of Emperors including an Ovipositing female. It was becoming a good day.

Emperor Dragonfly (Anax imperator) ovipositing at Arne. 

 It was the song of the Dartford Warbler that first caught my attention. Imagine the song of a Whitethroat (Sylvia communis), and consider the qualities and notes which ensure the song is often described as “scratchy.”   Now distil those scratchy qualities, concentrate that Sylvia scratchiness,  andyou will begin to imagine the song of the male Dartford Warbler.  The male caught my eye first too, a small, dark coloured bird, with a longish tail, proportions somewhere between a Cetti’s Warbler and a Long Tailed Tit. He alighted briefly at the top of the heather, sang a few notes, and dropped back into the thick tangle of waist high vegetation.  He reappeared and my eyes strained to see his features in the sun glare, his dark blue-grey back and wings contrasting little with his dark pink-red underparts, and he had an air of cultivated scruffiness.  Rooting in the gorse he popped up briefly with a beak full of spiders, before dropping down to stuff his spiders into the expectant mouth of a scruffy fledgling, brown and distinctly smaller than the adult, which had emerged from the vegetation.   The fledglings and the female never left the thick heather and gorse, appearing to my eye only briefly before returning to the shelter of the thick heather canopy, but the male returned to his commanding lookout and sang, re-stating his claim to this his fragment of the coastal heath, the precious resource upon which his family depend.  Perhaps by remaining in this prominent position he also provided a distraction display focussing the attention of birders, and any would-be predators, on him, allowing the more vulnerable youngsters to slip away.

It was a magical moment with these scruffy, charismatic little survivors, and conservation icons of the lowland heath.  It was heartening to know that, with many small birds finding their breeding cycles disrupted by the late snow this spring, at least some of this most cold-sensitive warblers had successfully fledged broods. This family appeared to be doing well.