Llanelli Naturalists Newsletter - May 2007 - No 7
Niel Matthews

In the naturalist's year, certain sites are visited at certain times on an annual almost ritualistic basis when various, usually hard to find, species can be found. This occurs during the short windows of opportunity presented when they either pass through or when they present themselves in the course of a very brief life-cycle. For my own part, for example, I often look for dotterel on the bare hilltops of the Black Mountain (Mynydd Du) in late April/early May, the black redstart in the environs of Llandeilo Church in early November, the club-tailed dragonfly along the Tywi in late May, and the white-letter hairstreak in July.

I had until recently no success at all with the last species. I had confined my searches to certain wooded 'cwms' where there were still elm trees (the larval food plant) or, where they had been seen by somebody else. Julian Friese had recorded this butterfly in "Penrhiwiau dingle" through which the Afon Araeth carves its steep-sided way to join the Tywi between Llandeilo and Bethlehem (SN 660236 approx). For many years I visited this spot, my hopes were raised on one occasion when hairstreaks were found coming down to the water to drink – but they were purples! I also undertook similar vigils in the valley of the Nant Gurrey-fach, between Penybanc and Salem. north of Llandeilo (SN 619247). Here, luxuriant elms still exist and one had to use a telescope to survey the quite busy activity of hairstreaks in the tree-tops. Even with this aid I wasn't unfortunately able to confirm white-letters: later on in July purple hairstreaks emerge to confuse matters: these can be identified by the silvery undersides (in sunshine) but one is then left to ponder the identity of darker specimens that one had seen. Similarly. isolated elms in Castle Woods had been examined, hairstreaks landing on the leaves revealing themselves to be purples when stretching out their wings to sunbathe.

One sunny day (13 July) in 2005, I was cycling along the lane between Cilsane Mill and Pentrefelin in the valley of the Mon Myddyfi (west of Llandeilo), when I suddenly realised that the hot sunny day was just in the right season for white-letters, that Julian Friese had seen one a little further up the valley the previous year (SN 598238). and that the tree I was passing might just be worth looking at. It was a small round-crowned wych elm of about 25 feet in height and standing on its own (SN 597226). After only a minute or so two, butterflies zoomed up from the top branches, spiralling tightly together, going quite high before returning after a short while. Being a low tree I was able to get good views of the butterflies after they landed. wings held closed and showing the white-letter 'W' above a brown background and the orange lunules near the rear edge of the hind-wings. There was one repeat performance of the spiralling flight by two others but otherwise only very brief darts in the canopy by singletons were observed. Success at last: and so easily come by!

Two days later, during a lunch time walk down to the Afon Tywi at Llandeilo, I subjected a similar looking elm tree (SN 635229) to the same examination and with a very similar result: two butterflies would spiral upwards before splitting and returning to the tree separately. whilst back at the tree, single insects would fly intermittently very rapidly in different parts of the canopy, most of the canopy showing such activity. After this, there were few opportunities to go looking for white-letters but my experience had shown that perhaps I had been looking in not wrong, but more difficult places. and easier results were to be had when looking at isolated or small groups of elms away from woodland. I went on to map where elms were still conspicuous along the railway line (where this last mentioned tree had been) between Llandeilo and Llandovery and along the parallel length of the A40, hoping to visit these trees in summer 2006.

The weather in July 2006 was ideal for white letter hairstreaks. but unfortunately transport difficulties meant I couldn't stick to my original plan and I was mostly reduced to walking or cycling to spots within reach of Llandeilo in my lunch times. Fortunately the time spent was productive enough. Approximately 22 sites (a site representing a tree or group of trees) were looked at over 8 days between 13 and 27 July. White-letter hairstreaks were observed at 7 while they may have been present at two further sites (fleeting glimpses only at Manordeilo and near King's Lodge). The season began with butterflies behaving in a similar way to last year at the 'railway tree' outside Llandeilo on t3 July. Spiralling flights by two butterflies together were again quite often observed. but also more probing flights in amongst twigs as well as one that flew away rapidly from the tree following the line south. Also, what looked very like a chrysalis suspended by a thread and moving quite vigorously in fairly breeze-less conditions was observed through binoculars. Most of the activity was in the top of the canopy but one butterfly did settle low down on a hazel. It seemed that while males were behaving territorially, some females were already laying eggs. A minimum of 4 adults was estimated.

The following day in equally good weather, I walked up to a fine hedgerow of elms roughly 20­25' in height, along the B road from Llandeilo to Talley and where a minor road leads off to Penybanc (SN 635245) After some minutes, white-letters appeared and activity was seen associated with five trees along a 100m length. They were seen perching three times but for the most part, quick darting flights was the predominant behaviour. the spiralling flight of presumably antagonistic males only seen on one occasion. These elms are all wych elms and showed little sign of disease. Along the road to Penybanc were more elms but no butterflies were seen here. possibly because the elms were of a different species (to my eyes at least).

Several sites were examined in the Nant Gurrey-fach valley, close to Llandeilo on the north side. The trees looked suitable (and so was the weather) but no white fetters were seen. The old route of the A40 before the bypass was built can slit be seen in places. such as the formerly famous bend at "Penrock" (SN 615234). Here. especially as there is no longer any need for highway maintenance, some particularly flourishing elms have grown up. On this occasion (July 21) the weather was more overcast and my impatience led me to adopt a tactic mentioned by Margaret Brooks and Charles Knight in their 'A Complete Guide to British Butterflies' where it is stated "A stick thrown up into the branches may disturb a few, thus betraying their presence." The road was suitably quiet and there was an abundance of sticks, so I had a go. When I eventually got my coordination right and made contact with an elm canopy at the beginning of the road, a hairstreak did exit promptly and flew to the opposite side of the road, from where it was dislodged again by my next throw. However, proceeding further down the road. I had no more success and was quite glad when the sun came out and I had no more need for these rather intrusive methods. A north-south hedgerow to the east of King's Lodge which meets this road has some fine elms, but these and a group at the junction may not be "glabra" but some other hybrid variety. Even so white-letters were again visible, for the most part darting through the canopy. No spiralling flights were observed, but one butterfly at least seemed to be egg-laying: it was flying into the base of twigs, crawling back out over the leaves and then taking off. Other similar exploratory flights were noted. One specimen that seemed to be very attached to a particular ash tree was no doubt feeding off the honey-dew in the canopy and this individual remained active when the sun went in. One hairstreak was seen to fly over or leave the group of larger elms by the roadside and fly off, following the hedgerow eastwards back towards Pen rock.

25 July was another hot sunny day and I looked at several sites in the Cilsane area. I was glad to see that the butterflies were again active at the isolated tree where they were seen last year (SN 597226). About two were seen in the top of the tree where some of the leaves were wilting as a result of the recent hot weather. Only very brief flights were seen. Several elms were growing in a small cwm near Birdshill (SN 603228). I had to wait quite a long time before, apart from possible glimpses. I eventually saw one flying quite low in the canopy, laying eggs in the lower branches and affording good views. Purple hairstreaks were also observed in this area flying from the large oaks in some of the hedgerows. One hairstreak in a group of elms by the main road could have been either of the two species.

The following day there was a possible sighting, a brief glimpse only, in roadside elms at Manordeilo, and the day after that equally brief flights were noted at the Penrock site. It appeared that the butterflies were getting much harder to spot as the end of their adult existence was reached. Over a period of only two weeks. I had observed changing behaviours, starting with territorial males (deduced from the spiralling flights). then egg-laying females and finally individuals of either sex loafing around in the canopy.

This brief survey of the Llandeilo area suggests that the white-letter hairstreak may be a lot commoner than we had realised. As far as I know there have been few records made in the county: apart from those sightings mentioned at Penrhiwiau Wood and Pont Pentrefelin and the ones seen at Pontynyswen near Brechfa in the 1980s, there were records from coastal areas in the mid-1970s at Pwll and Stradey Woods, and many years before that and long before the outbreak of Dutch elm disease they were seen at Ferryside ("in numbers", 1947) and at Cynwyl Elfed (1950s), (records per Ian Morgan). Elms are a fairly common component in hedgerows. at least locally (especially in the Tywi Valley and along the coast) and there appears to have been some resurgence, though a few trees still show signs of die-back in the canopy. alerting us to the ever present threat of a fresh outbreak of Dutch elm disease. Should we have any concerns about the future of the white-letter hairstreak in Carmarthenshire? As the elms that white-letters like (we don't know much about the importance of woodland elms) are found along linear features some impacts can be expected from management activities on the part of the highway and railway authorities as well as from regular hedgerow maintenance on farmland. The butterfly is afforded minimal legal protection and is not listed as a UK BAP species, It could be put on Carmarthenshire's LBAP list if it was considered that the habitat was under threat. While it may not be under threat there remains no mechanism whereby its conservation can be promoted other than by a general appreciation of the elms on which it survives.

References

Brooks, M. and Knight, C. (1982). A Complete Guide to British Butterflies. Jonathan Cape. Morgan. I.K. (1989). A Provisional Review of the Butterflies of Carmarthenshire. Unpublished Report, Nature Conservancy Council. Dyfed-Powys Region: 34-35.

White-letter hairstreak records in the Llandeilo area 2004-6

Cilsane SN 597226 13/07/06 & 25/07/06 N Matthews
Pont Pentrefelin SN 598238 D7104 J. Friese
Birdshill Farm SN 603228 25/07/06 N. Matthews
King's Lodge SN 612236 & SN613237 21 & 27/07/06 N Matthews
Penrock SN 615234 21/07/06 N. Matthews
Rhosmaen - New Inn SN 635245 14/0706 N. Matthews
Llandeilo SN 635229 15/07/05 & 13/07/06 N. Matthews