This week is Wales Nature Week, a celebration of Wales’ nature in all its forms.

To mark the occasion, we’re celebrating the discovery of a rare and particularly elusive species at Bwlch Corog – the Welsh Clearwing moth.

First discovered near Llangollen in 1854, hence its common names, the Welsh Clearwing (Cliradain Gymreig, Synanthedon scoliaeformis) is a distinctive moth. With its clear wings, its habit of flying in daytime, and its wasp-like body, evolved to avoid predation, you might think it would be easy to spot. But it needs a very particular habitat to survive, and even when present it has a reputation for evading lepidopterists.

The female lays her eggs on the trunks of birch trees – which are numerous in many parts of Wales and the UK. But the Welsh Clearwing is thought to require trees need that are mature, with healthy wood, and in open areas rather than in shady woodland – a far less common set of circumstances. Having several specimens of mature birch at the edge of the Celtic rainforest, and in the open woodland and on the ffridd (upland wood pasture) beyond, Bwlch Corog was identified several years ago as a site where the Welsh Clearwing might be present.

Known at only a few sites in Wales, generally in Meirionydd and Montgomeryshire, the Welsh Clearwing had been spotted near Glaspwll prior to Coetir Anian’s arrival at Bwlch Corog, so we have long suspected that we may have it on the site.  Although it lives within the tree as a caterpillar for two or even three years, after its emergence in early summer it only flies for a few weeks, and spends most of that time up in the canopy. Add to this the need for still, dry weather for traps to be effective, and you have a difficult moth to find. We have seen likely evidence of the moth before, in the form of the caterpillars’ exit holes in birch trunks, but until now no definitive proof of the moths’ presence.

Pavel Kirillov CC BY-SA 2.0 via Wikimedia Commons

This is the third year we’ve searched, using pheromone lures which attract the male moths to traps. The work has been done in partnership with Phil McGregor, our regular moth surveyor and a member of Montgomeryshire moth group. You can read his account of the discovery, and see pictures of some of the other species captured this summer, here on his blog. We have in past years struggled to find a good day to survey for these moths – last summer was unusually wet and windy here – and the Welsh Clearwing emerges only on clear, sunny, warm mornings. This year, however, we were delighted to find the moths following a couple of days of warm, settled weather:  a total of 5 males were found on birch trees in old hedges, in two different locations on the boundary between Bwlch Corog and Cefn Coch farm.

We will be working with our neighbour Joe Hope at Cefn Coch, where there is also suitable habitat for the Clearwing, to ensure the moths have the best possible chance of thriving across both sites. We’ll do this by expanding birch woods, diversifying the age structure of the trees, and maintaining cleared areas (by clearing scrub and grazing with cattle) around gnarled veteran trees in spots where the sun catches the trunk, in the hope of providing a home for these rare moths now and into the future.  This will also benefit a range of other species that live on the ffridd such as Redstart, Tree Pipit and Pied Flycatcher, and our population of Hazel Dormice, along with more generalist species such as the Tawny Owl.

The Welsh Clearwing was captured (and released unharmed) on a weekend of surveying that saw the total number of moths discovered at Bwlch Corog rise to 276. We’ll publish another post soon with some of the other interesting species from this summer, but we were so pleased to finally see a Welsh Clearwing, we thought it deserved a post of its own.

And we hope there are plenty more species still to be found.