Llanelli Naturalists Newsletter - September 1983
Ian Morgan

This summer has seen a large influx of Clouded Yellows into the country and South Carmarthenshire has had its fair share of this migrant with records from St. Clears in the west to Ammanford in the east. Doubtless many sightings have not been reported but numbers have certainly been high with numbers exceeding 10 at Machynys (C. Jones) and Pwll (G. Harper); five, including a mating pair, were seen at Upper Lliedi Reservoir. Single records have been numerous during June-August, the last time that such numbers were seen was in the similarly hot summer of 1976; though one or two are seen most years. Clouded Yellows could be seen flying landwards off the sea at Cefn Sidan together with Large Whites.

Other continental insect migrants seen in quantity this year were the Silver Y Moth (Plusia gamma) and the Common Darter (Sympetrum striolatum) a sp. of dragonfly which often wanders far from water and visits woodland, gardens and even beaches.

The Marbled White, a distinctive white and black chequered member of the Brown Family (which includes familiar spp. such as the Meadow Brown and Gatekeeper) is common at certain sites in South Carmarthenshire, - though various entomological authors incorrectly state that it is only found on calcareous soils in South-east England and the Midlands: It has long been known to be abundant at Tywyn and Pembrey Burrows (with most seen July-August) but survey work in the mid 1970’s showed it to be quite widespread in the South-east of the country. What is interesting is that many of these sites are on non-calcareous soils (to which this sp. was thought to be limited); many localities where the Marbled White occurs are in fact very acid such as bogland near Four Roads (Mynydd-y-Garreg).

What all these sites do have in common however is that they are permanent grassland often with a considerable admixture of rank vegetation. Three new sites found for the Marbled White in 1983 - Brondini peat bogs, to the West of Pont Morlais (Llannon) and bogs near Llwyn Têg, Llannon; all have these characteristics.

Currently the sp, is known from the sites already stated, the Gwendraeth Valley, Pwll-Stradey-Five Roads area, North-east of Upper Lliedi Reservoir and the Capel Hendre area. There is an isolated (1976) record for Llyn-y-Fan-Fach. Some colonies have been known for some length of time so that Marbled Whites recorded there are not “wanderers” in good summer weather. Any records of this sp. will be welcomed especially with habitat notes and G.R.’s will be welcomed.

Finally, any information on the occurrences of Brimstone butterflies would be appreciated; it is a scarce and local butterfly in Carmarthenshire.