While our butterflies are well known, our moth fauna is much less so. This is partly because of the nocturnal habits of most species and partly because there are so many more species of moth than butterfly. In recent decades through the Glamorgan Moth Club, a band of dedicated local naturalists with their moth traps, are expanding our understanding of Glamorgan and RCT’s moth fauna.

Our moth fauna is spit into micro-moths and macro-moths. Using the excellent Glamorgan Moth Atlas, there are 96 species which are nationally rare, scarce or uncommon in Glamorgan (51) with a further 45 species on the Welsh Section 7 list (formerly S.42) that are not identified as scarce or rare in Glamorgan (of which 11 are scarce in RCT). Of these 62 species are found in RCT. The following is an attempt to group those species into broad habitat types. It is acknowledged this process is much harder for moths than butterflies because we know less about their specific habitat requirements.

Woodland species

There are perhaps 15 woodland species: goat moth, lunar hornet moth, satin lutestring, orange underwing, maiden's blush, alder kitten, chocolate tip, double dart, lead coloured drab, brown spot pinion, dusky lemon sallow, autumn thorn, dusky thorn, September thorn and brindled beauty. Looking at just one of these, the goat moth a Nationally Scarce B species. It is big silvery/brown moth which lives in wet woodland and marshy sites. Its larvae spend up to four years slowly eating their way through the soft heartwood of willows and alder trees, emitting a goat-like odour. There is a cluster of records from wet woodlands in the Cynon Valley and an old record from the Llantwit Fardre area and the species may be much more widespread using the wet woodlands and wooded marshy margins of many of our wetland sites.

Rhos Pasture/Marshy grassland/Heathland

15 species appear to be particularly associated with marshy grassland and heathland habitats: ruddy carpet, narrow bordered bee hawk, scarlet tiger, stout dart, double line, conformist, crescent, oblique carpet, minor shoulder-knot, heath rustic, beautiful yellow underwing, dark brocade, confused, scarce silver y, neglected rustic and anomalous.

Of these, the double-line is a great example of what can happen with increased recording attention. At the time of the old Biodiversity Action Plan the double-line (a name that describes two parallel lines on the forewings) was afforded its own national action plan because of a rapid decline in distribution across southern Britain. However, in the subsequent years moth recorders in Glamorgan revealed that the wet grasslands of Glamorgan (and RCT) are a UK stronghold for the species, as a result it is no longer on the danger list: a classic case of voluntary effort informing the national conservation strategy.

Another marshy grassland species of note is the narrow-bordered bee hawk whose larvae feed on devil’s-bit scabious and which shares rhos pasture habitats with the marsh fritillary butterfly. However, it much rarer than even the marsh fritillary although in recent years the moth has been seen much more frequently in the Hirwaun area, and there is huge potential for it in the extensive marshy grasslands of Rhos Tonyrefail SSSI and the Llantrisant/Llantwit Fardre area.

Acid Grassland/Ffridd/open woodland

The open acid grasslands, mosaics of ffridd and open woodland of RCT include their own moth faunas, and six may be associated with these habitats: forester, chimney sweeper, Welsh wave, wood tiger, barred chestnut and star-wort. The forester is a day-flying emerald, green moth whose larvae eat sorrel. After a lengthy period without records for RCT, the moth was discovered in un-improved acid grassland in Blaenrhondda Park, Blaenrhondda in 2018, and a second site at the opposite end of the County Borough in colliery spoil above Nant Garw. The Blaenrhondda Park site is now being managed to prevent the acid grassland over-growing with bramble and is one of the Living Landscape pilot sites.

The second moth to highlight is the chimney sweep. This is sooty-black day flying moth is much more attractive than that description suggests. Its larvae feed on pignut which is a common flower of acid grasslands and RCT is a stronghold for the moth in Glamorgan. Good populations of the moth occur in the Upper Cynon Valley and Tonyrefail. Both the forester and chimney sweep are easily identifiable day flying moths, and it is likely both will be found elsewhere, if we can encourage more people to have a look for them.

Lowland dry neutral grassland/limestone/brownfield

Seven species are broadly associated with dry, species rich grassland and scrub habitat: six-belted clearwing, dusky sallow, small yellow underwing, grass rivulet, feathered gothic and Hawthorn's pug. The wasp mimicking, six-belted clearwing is a Nationally Scarce B species, which through the use of specific pheromone lures by RCT ‘moth-ers’ is now know to be well established in RCT, often on post-industrial sites where its larval foodplant bird’s-foot trefoil grows over concrete footings and hardstanding.

Forestry and Upland/Bog

Eleven upland species are associated with upland habitats, including relic areas within forestry (two of the pug species listed are true conifer species): small argent and sable, cloaked pug, bleached pug, dwarf pug, smoky wave, grey mountain carpet, northern rustic, glaucous shears, light knot grass, golden spangle and marsh oblique-barred. The small argent and sable is a beautiful black and white chequered moth with heath bedstraw its lava foodplant, the grey mountain carpet is an upland moth of mid and north Wales which is found on heather/wimberry moorland in the RCT uplands and the marsh oblique-barred in RCT is a bog species associated with our upland peatlands.

Reedbed/swamp

Of the two reedbed/swamp moths, the obscure wainscot is a delicately marked reedbed species, its only inland Glamorgan site being a reedbed at Cwm Colliery Beddau. The double lobed has been recorded in several valley bottom swamp sites in the Cynon Valley.

Garden/generalist

These six species have no definable habitat association: currant clearwing, spinach, cosmopolitan, chamomile shark, golden plusia and garden tiger. The currant clearwing is found on old garden/allotment sites with old black and red current bushes. The garden tiger was once a common species, the woolly bear caterpillars being a familiar garden sight. However climate change and warmer winters have not suited the moth which is now distinctly uncommon in RCT.

If you want to learn more about moths then join the Glamorgan Moth Group, get hold of one of the excellent new moth identification books now available and consider buying a moth trap.