Wednesday, 7 August 2019

Cors Dyfi Nature Reserve - 3rd Aug 19 - Coming up roses!

Well, where to begin.... The forecast for once was looking extremely favourable and there was a crowd of 26 people eagerly anticipating some moth action even before the traps were switched on. Though before they'd arrived a July Highflyer had already been found on the visitor centre wall.

Common Rustic agg. feeding on Molinia - Gavin Chambers

With Tom's help from the Cors Dyfi Osprey project we had traps up and running from about 9.30pm, with 7 traps and a white sheet. Peter gave a short talk about the moths and then we were all set free to hunt out the moths. It wasn't long before moths started to be potted and ID'd with Small Rufous, Smoky Wainscot and the first rosy of the night in the form of a Rosy Rustic. Along the boardwalk it was interesting to note numerous moths, including the Bordered Beauty, seemingly feeding/nectaring on molinia seed heads which must have just bloomed, as much as grass does!

Scarce Silver-lines - Gavin Chambers

More colourful moths then appeared with Orange Swift, Ruby Tiger and the intricately marked Antler Moth wowing the crowd of 'mothers'. As often is the case, the white sheet was a great spectacle (we caught one of these too) for the public with a great variety posing nicely, such as the striking Black Arches, stunning green Scarce Silver-lines (bigger than I'd imagined!) and mezmerising Gold Spots.

Webb's Wainscot - Greg Osborn
It was extremely useful having numerous footmen on site, despite just lingering around the moth traps. We ended up with a few types; Common, Scarce, Dingy, Buff and the superb Rosy Footman (the second and probably best looking rosy of the night). With the reedbed on site it was no surprise to catch numerous Wainscots. The stand out of these was a subtly but destinctly marked Webb's Wainscot which is only the 2nd county record after one caught at Cors Dyfi in 2015.

There were plenty of micro moths around, including the large Patania ruralis (Mother of Pearl) and gold spangled Argyresthia goedartella. However, there were also plenty of tiny apparently non-descript species which were quickly put in front of the experts, it was a great relief to see Douglas turn up to keep us right! One of only a couple of migrant species was the small Plutella xylostella (Diamond-back Moth) which was dwarfed by the other common migrant of the Silver Y.

Rosy Marsh Moth - Ben Porter (
We got to midnight with most people having left for home, but the moths were going strong with 100's now swarming around traps. Clouds of Large Yellow Underwing made it trickier to pick out something different but a quick look through some of the egg boxes revealed one of the specialities for the reserve, the rarest rosy of the night and perhaps most sort after amongst most of the nights 'mothers', the Rosy Marsh Moth. A Red Data Book species restricted to only a handful of sites in the UK, with larvae feeding on bog myrtle. They are so rare that even the police had to drop by to check them out, at least that's our story...

A heavy rain show around 1am had us sheltering for a short time before starting to pack up around 1.30am. As always more species were discovered as we emptied the traps such as both the Copper Underwing and Svensson's Copper Underwing, Miller and Tawny Speckled Pug along with the more unusual Dotted Carpet, Clouded Magpie and Small Argent and Sable. There was also a couple of hitch-hikings with a Cloaked Minor (arguably the moth of the night 😉) on my head and a Slender Brindle on Mel's shirt. Surprisingly the elephant in the room was missed by all white sheet onlookers all night, as an Elephant Hawk-moth larvae was found munching on willowherb below the sheet not long before packing up, the adult having been found earlier in the night.

Elephant Hawk-moth Larvae (left) and Adult (right) - Mel Jones

In total we finished with a mammoth 114 macro species and 58 micros totalling the highest ever catch during a moth event and we still managed to leave at 2am! For a full list of species please click here.

Thank you to everyone for coming along and to Tom for being on site to keep us under control on what turned out to be a great night for moths. Thanks also to the photographers for making it hard for me to pick which ones to use, they were all great. Fingers crossed the weather is turning in our favour for moth events this year and we get a warm, dry day for the next event at Wern Claypits, a daytime event (more details here).


  1. Yes what a night, the traps, white sheet, in fact everywhere was alive with moths.... I'm still pulling moths out of my hair now!

    An excellent event and report, thanks Gavin.


  2. What a night! Great summary and write-up Gavin, and brilliant to see the final species list. By far the most species I've ever had on a mothing night!

    Fingers crossed for the next event.


  3. Great report, Gavin. Very glad I could make it - was a brilliant night (marred only by the most stressful journey of my life on the way home trying to find an open petrol station on an empty tank!).

    The double figures of Rosy Marsh were also the highest ever for the county I think? Think we can be pretty confident the species is breeding on the site.


  4. What a night - and a brilliant report Gavin, which I'm thrilled to read as we were away in Scotland on the night. Now I can almost feel I was at Cors Dyfi!

  5. Really sorry to have missed all the action! Well done everyone - great photos and great report. I think we did deserve a good night after the previous events! Looking forward to Wern Claypits.