Llanelli Naturalists Newsletter - November 2000 - No 66
Ian Morgan
A visit to Cors Goch Llanllwch (SN363187) just south west of Carmarthen on 25 July 2000 yielded many of the scarce or rare invertebrates for which this Wildlife Trust West Wales reserve is important. The site was accessed via Cwm Coch Farm and the main reason for the visit was to try to find the rare bogland salticid or 'jumping spider' Heliophanus dampfi, which is known from Cors Fochno in Ceredigion. As Adrian Fowles a few years ago had netted a sub-adult Heliophanus from the heather at Cors Goch, Llanllwch and Mike Bailey (the warden) at Cors Fochno had told me that they 'were out' at the latter site, I felt that there was a chance of finding them.
Unfortunately, I failed, but in the process of sweeping (with my net) the Heather Calluna vulgaris and Bog Myrtle Myrica gale, several species of note were taken. These included the well-named Beautiful Yellow Underwing Anarta myrtilli here - I believe - at its only known vice-county site. Both a freshlyemerged adult moth and the distinctive caterpillars were seen.
A feature of Cors Goch is the sphagnum-filled bog-pools, with their attractive swathes of White Beaksedge Rhynchospora alba, Bog Asphodel Narthecium ossifragum and the low, hugging plants of insectivorous Round-leaved Sundew Drosera rotundifolia. Here, my attention was drawn to some small whitish pyralid moths. One was captured and it subsequently proved to be Crambus uliginosellus, new to Carmarthenshire, whilst over another hollow, the colourful large rove beetle Staphylinus dimidiaticornis was seen. Also associated with these natural sphagnum-hollows (the origin of which is unsure), as well as the now moss-filled ponds and ditches created by the Wildlife Trust's recent positive management, is the very scarce Small Red Damselfly Ceriagrion tenellum. Markedly confined to a few sites in south-west Britain, this specialist should not be confused with the slightly bigger Large Red Damselfly Pyrrhosoma nymphula (a spring/early summer species which is common in Carmarthenshire). The Small Red Damselfly is much weaker-flying, with red legs and to my eyes, the reddish hue of the body reminds me of the wax once used to seal letters. I counted at least fifteen individuals on my visit.
Walking through the rank heather and other vegetation, I regularly disturbed Bog Bush-crickets Metrioptera brachyptera, with bright green undersides and, in common with the Small Red Damselfly, here at its only Carmarthenshire locality. Whilst unsuccessfully sweeping for the jumping spider, I regularly netted the shiny Black Bog Ant Formica candida, a very rare species indeed which elsewhere is confined only to the Hampshire and Dorset heaths and Rhosili Down on Gower.
Apart from numerous clegs Haematopota sp., the chunky horsefly Tabanus sudeticus was seen, but there was no sign of another Cors Coch Llanllwch speciality, Atylotus fulva, a very scarce green-eyed and chestnutbodied horsefly which has been previously recorded.
