Thanks to volunteer Phil for this report and for all his hard work surveying dragonflies & damselflies at our Arun Valley reserves this year.
I first became aware of willow emerald damselflies about 7 years ago when some naturalist friends were considering a trip to East Anglia to find this relatively new species for the UK which had spread from Europe, maybe as a result of climate change. A little research established that, after a few fleeting visits over many years, they were found in some numbers in Suffolk and neighbouring parts of Norfolk and Essex in 2009. The trip did not materialise but very soon afterwards I heard that a colony had been found at a Surrey Wildlife Trust nature reserve, The Moors, near Redhill not far from where I live, cueing several fruitless visits in search of these.
Then I became aware of willow emeralds being found at RSPB Rainham Marshes, closer to their original East Anglian bridgehead so I paid a visit there and, following instructions, duly found one. Some years later while passing through the Moors on a walk to Redhill I finally encountered one there. Then in 2019 I came across this interesting pair at Stodmarsh National Nature Reserve near Canterbury, illustrating their penchant for perching in trees.
It is interesting to speculate whether the firmly clasped female in this photo is trying to balance, escape, or maybe wondering how she can curl herself up to access the bark and start laying eggs
For a few years the damselfly afficionados at Pulborough Brooks have been expecting to find willow emeralds on the reserve and some of us agreed that the most likely place would be at the Dipping Platforms where a willow grows out of the ditch. This is a key ingredient because the females lay their eggs into tree bark overhanging water, often willows, but sometimes alder, hawthorn, birch and elder. When the eggs hatch into larvae these drop off into the water where they spend most of their lifecycle before emerging as adults to breed.
In the meantime, willow emeralds had been slowly spreading into West Sussex and as of 2018 colonies had become established at Warnham Nature Reserve near Horsham, which led to another fruitless visit, and Sussex Wildlife Trust at Woods Mill. It seemed that a colony must reach Pulborough soon.
Finally in 2020 there was a recorded sighting on the east side of the North Brooks, spotted by one of our ex-wardens who still lives nearby. This year willow emeralds have been spotted several times by colleagues Graham and Neil and these have included a few mating pairs suggesting that they will be here to stay. And sure enough most of the sightings have been close to the willow at the Dipping Platforms. There has also been a sighting at Black Pond which I’m less sure about as a suitable habitat, but time will tell.
A few days after Graham announced his first sighting of the year, I was undertaking a dragonfly and damselfly survey at Amberley Wildbrooks about 2 miles away and, courtesy of another colleague Malcolm, came across a willow emerald perched on a drooping branch of a weeping willow. This is probably the first ever sighting there and I duly submitted it to the British Dragonfly Society along with this photo of the insect perched on a leaf.
Then finally on 17th September after a very brief glimpse earlier in the week I finally had my first good sighting at Pulborough Brooks duly present at the Dipping Platforms perching on the grass stems growing by the edge of the ditch.
For any readers looking for these insects the willow emerald is larger and more robust than the common emerald damselfly and does not develop any of the blue colouration seen in this photo of a common emerald.
Also willow emeralds have pale wing spots unlike the dark ones of the common emerald and I find this is the easiest diagnostic difference to look for.
Common emeralds can be seen in July to September in good numbers around Black Pond at Pulborough Brooks and a few may also be found by the Dipping Platforms. Willow emeralds fly a little later from August through to October.
The wait at Pulborough Brooks is now well and truly over, and this marks the end of an interesting few years of discovery for me.