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7 July 2023 Dusky falls


The big moth news of summer 2023 has been the realisation that Dusky Clearwing is alive and well in Britain. Small numbers were found in the late 19th and early 20th century, essentially south of a line connecting Essex and the Severn, with the last in modern Oxfordshire in 1924. To aid its potential rediscovery, Anglian Lepidopteran Supplies used to give away Dusky Clearwing lures (TAB) free when you bought their set. I used these between 2016 and 2019, targeting sea buckthorn in Norfolk - a habitat that the species was known to use on the continent. 

Nearly a century later, a female was discovered by chance on poplars in Warwickshire in 2021. This changed things: perhaps Dusky Clearwing did still occur In Britain. Nevertheless, anyone who tried their luck with TAB during 2022 clearly failed. Then, in June this year, Ben Sale lured a Dusky Clearwing to his garden in Fordham (east Cambridgeshire). That evening, Colin Plant encouraged moth-era to try their luck in sites with poplar and aspen. The following day, friends and I tried the aspen-rich Foxley Wood in Norfolk, but without luck. In Suffolk, however, under ten miles from Ben Sale's place, one was lured at Barton Mills

Now this was really exciting! It suggested that Ben's record was no one-off, and that there was a population in East Anglia. This galvanised me to the point of obsession, and I spent the moth's afternoon/evening flight period (15h-19h or 20h) trying along a Suffolk river with old poplars, a Suffolk floodplain with old poplars, and a Suffolk woodland with a neat patch of aspen. All without success. During a hugely busy work and family period, I was wasting effort and valuable time. 

With these three individuals in pots temporarily, to show other mothers arriving on site, I continued luring - and had a fourth individual come in. It didn't enter the trap, but merely investigated it for about a minute. 

Since Ben's lucky first encounter, Dusky Clearwing has been found in Bedfordshire, at RSPB Lakenheath, at a site near Cambridge, at three sites in Warwickshire (although that might include Steven Falk's 2021 location) and possibly elsewhere too. At the site we found, I man aware of three groups who have tried luring without success. (For the avoidance of doubt, all of the clearwings we caught were released on site.) Efferts at apparently suitable Norfolk sites (including in the Brecks) have been unsuccessful. Luring in my garden unsurprisingly likewise. 


So what is going on? One possibility is recolonisation. That would explain the absence of records for a hundred years, and the sudden contemporary cluster. However, it seems surprising that none have been recorded further south. To my mind, this suggests that the species might have been present all along, undetected. Perhaps those who had the TAB lure were not using it (I certainly stopped after four summers' trying). Perhaps they were trying it, but only in their garden, rather than in poplar- or aspen-rich habitat. Whatever, it doesn't seem to be widespread: I understand plenty of people have been trying across southern England, but it has only been found between Warwickshire and west Suffolk. .Hopefully someone will write up all the records at some point, and suggest where else might be tried - and give a view on optimum habitat. Perhaps it will prove to be in poplars in urban areas, as on the continent. What a story.

It is not for me to reveal the exact location, but the habitat was interesting. Wet Carr woodland alongside a river, with mixed alder, willow and poplar - but the exact transit was surrounded by aspen. 


Wildlife

James Lowen 

And then Ben Sale caught another in his garden. This changed everything. There was, presumably, a population within a mile of Ben's house. Now we knew only the village where Ben lived, but that, plus OS maps and Google Earth was enough for Alan Lewis, Jack Morris, Andy Symes and I to independently identify a very suitable area nearby. Bumping into Alan while dipping a reported Scop's Owl in Norfolk, it transpired that he had spent that day luring unsuccessfully. I suggested that we might try a more extensive area just to the south. We arranged to meet there the following afternoon. I was trying my luck at a nearby site when Alan messaged me to say that he had caught one! By the time I reached the site, he had caught a second. Shortly after I arrived, a third arrived - all three in by 15h45, ahead of the expected peak flight time of c.17h00. Scenes!