Eyarth Rocks, Ruthin, Denbighshire

Eyarth Rocks, Pwll Glas nr Ruthin

Species to look out for

The limestone pavement of this fine hilltop reserve is some of the best to be found in Wales. It is being carefully managed to sustain North Wales' strongest populations of the threatened Pearl-bordered Fritillary.

Species to look out for


  • Pearl-bordered Fritillary
  • White-letter Hairstreak
  • Grizzled Skipper
  • Dingy Skipper
  • Dark Green Fritillary
  • Brown Argus                                            
  • Common Blue                                          
  • Small Pearl-bordered Fritillary

Notable plants

  • Mountain Melick
  • Moonwort
  • Hound's-tongue
  • Greater Butterfly Orchid


The Eyarth Rocks reserve is part of Craig-adwy-wynt, one of the richest butterfly sites in North Wales;  32 of the 34 species known to occur in the region have been recorded on this limestone hill-top Site of Special Scientific Interest, and most breed there.

The population of Pearl-bordered Fritillary has grown strongly since 2002 when BC bought and started managing the site. The limestone pavement flora is exceptional and the site provides magnificent views of the area.

Sheep are grazed on the reserve to help control the scrub growth and break up the bracken cover so that more violets can flourish for the Pearl-bordered Fritillary caterpillars to eat..

Area: 8.4 hectares

To view a documentary about the Pearl-bordered Fritillary, made by Dream Catcher Films over 5 years at Eyarth click here.


Map Reference: SJ 122 540 Ordnance Survey map: 116

Eyarth Rocks reserve is about 4.5 km south of Ruthin in Denbighshire. To reach the reserve entrance gateway in the northern boundary wall, at OS Map Grid Reference SS 122 542 follow the public footpaths from Pwll-glâs or from Eyarth Bridge. Outside of the villages of Pwl Glâs and Llanfair DC Car parking availability is limited (for example near Eyarth Brdige).

By bike: It is about 18 miles by road from Wrexham railway station to Pwll-glâs.  There is no current Sustrans cycle route near the site. 

By Bus: There is a bus route from Ruthin to Eyarth Bridge and Pwll-glâs. Please check a website such as Traveline Cymru to get up to date information

Site Access and safety

Our suggested access routes involve walks of about 1 km, moderately steep in places, up from the scenic river Clwyd valley. The ground can be uneven and requires strong foot-wear. The limestone pavement surfaces comprises a myriad of ‘clints’ and ‘grikes’ - narrow crevices that catch the feet of unwary walkers. Please take great care on the western side of the reserve where there is an un-fenced cliff edge.

The hill fort remains are on neighbouring private land, not the reserve.


Russel Hobson

  • E-mail: wales@butterfly-conservation.org
  • Telephone: 01792 642972 or 07736 229593

Eyarth Rocks Reserve Leaflet