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Wednesday, 13 May 2015

Recording at Nant y Bai, Rhandirmwyn

Sinead Lynch of the Bumblebee Conservation Trust wanted to see the upland bumblebee Bombus monticola, a species that she had not seen. As I had recorded it at the old lead mine site at Nant y Bai last summer and because the site had good access, a recording `jolly` was arranged, with about ten attendees. Among the latter was an old friend, Mark Pavett of Cardiff Museum, who I had n`t seen for about twenty years. Mark specialises in the aculeate hymenoptera but also has a broad knowledge of other invertebrate groups such as the diptera and coleoptera. Also present was Vaughn Matthews of our Carmarthenshire Moth Group. The weather was kind (though the most persistent sunshine appeared as we were leaving in mid afternoon!), and we had a good time making useful records of all sorts of wildlife.
The moth highlight for me was spotting a glaucous shears resting on a heathy slope, a nicely marked and well-coloured individual. The only other moths that I noted were the common Cydia ulicetana on gorse and several drinker caterpillars; a few species of butterflies were spotted, including a fair number of green hairstreaks (which particularly pleased Vaughn - a new `tick` for him!). Co-incidentally, my first green hairstreak (if my memory serves me correctly) was on the hillside opposite, overlooking the Tywi - but back in 1973. Time flies!
Other (non-moth) highlights for me today included the hoverfly Sphegina sibirica, a species that I had not seen before*, and an `old friend`, the little jumping spider Evarcha falcata.

* associated with Picea (as was mine) the technical determination of this species: the underside of the base of the abdomen was checked and was entirely membraneous with no plate. It is a species that was n`t recorded in the UK until the early 1990s, but has recently been seen in neighbouring Brecs...something for Sam to look out for in the Brechfa Forest area.

                                             Above: a general view looking into the site.
                                                     Above: the glaucous shears.
                         Above: a drinker caterpillar - many, of different sizes, were seen.
                                            Above: one of the many green hairstreaks seen.


  1. A most interesting blog, Ian. Many congratulations on your Glaucous Shears. I've got some catching up to do!

  2. Fabulous location, the Hairstreaks must have been superb.

  3. We are hoping to spend a few days at the Rhandirmywn camp site shortly - can you tell me how to access Nant y Bai ?? e.g. Grid Ref? I can see a village/hamlet on the map but wondered where the lead mine was.
    Rosemary (Pembs moth-er who reads this website regularly)

  4. Rosemary - just follow the footpath eastwards and upslope from SN776445. As you follow it you will see the open area to your left (N) with spoil and much Silene maritima etc and further to the E is the more extensive open area around the old mine itself. If you trap there, I`m sure that you`ll have goodies!
    Another good (longer) walk is Cwm Pysgotwr. Park at SN776472 (approx. below Craig Clyngwyn) and walk NW through Allt Rhyd y Groes NNR, carrying on the S (Carms) side of the river - fantastic scenery and very wildlife-rich.

  5. Thanks very much Ian. (PS I always enjoy your chatty posts!)

  6. Sphegina sibirica occurs here at Cnwc y Llwyn. I was a bit confused by Sphegina because the first couple I checked here were S clunipes and I assumed that was what the large numbers on flowering Saxifraga were. I subsequently found a couple dead indoors, and they turned out to be S sibirica. The Saxifrage swarm could have been either.

  7. Ah!....I sort of suspected that you may have already beaten me to it with sibirica Sam!