Welsh Pearls - Pearl-bordered Fritillaries at Eyarth Rocks

Having never seen Pearl-bordered Fritillary before and sadly missing them at Glasdrum Wood earlier in the week, reports of a number of individuals on the wing at Eyarth Rocks near Ruthin saw me and Alex plan a visit during half term to try and catch up with them.

Eventually arriving on site, we made our way up the steep woodland slopes to the start of the reserve, navigating the many un-signposted tracks in the wood (with a few wrong turns) before the trees opened up to reveal the sunny hill top summit. Surrounded by open stands of bracken, the area was clearly being managed with Pearl-bordered Fritillaries in mind, and within a matter of minutes we had seen our first individual gliding majestically by.

Despite exploring the summit, it transpired the small patch of ground right at the start near the gate and entrance sign was the most productive, and we had up to four individuals feeding on the buttercups and Birds-foot Trefoil in the vicinity.

Exploring the dead bracken at the very top of the hill also revealed a single ovipositing female – fascinating to watch as she laid her tiny eggs on to the small violet leaves in the undergrowth.

Female Pearl-bordered Fritillary laying eggs on the violet leaves

The violet foodplant of the caterpillars

Eyarth Rocks was also alive with good numbers of Small Heaths, but despite this, we didn’t see any other species, nor the Small Pearl-bordered Fritillaries that also occur here (they tend to fly later in the season than the Pearl-bordered).

The view from the top of the hill

Quite similar to Small Pearl-bordered, Pearl-bordered Fritillaries generally appear a much paler shade of orange which is quite noticeable in flight, and when landed have a row of chevrons at the bottom of the forewing which appear to ‘float’ (they are attached to the outer margin on the edge of the wing on Small Pearl-bordered). The underside of Pearl-bordered Fritillaries is also distinctive, with two ‘pearls’ visible in comparison to the mosaic of white, orange and brown patterns that Small Pearl-bordered exhibit.

Small Pearl-bordered on the left and Pearl-bordered on the right. Note the floating chevrons on the bottom of the forewing in Pearl-bordered, as well as the row of spots being positioned further towards the middle (in Small Pearl-bordered the spots are closer to the edge of the wing)

 Requiring a habitat consisting of open bracken and violets (the caterpillar foodplant) to thrive, Eyarth Rocks is currently being managed by Butterfly Conservation to provide the perfect conditions for Pearl-bordered Fritillaries to survive in, and hopefully their numbers will continue to increase here.

Once common and widespread, Pearl-bordered Fritillaries are now one of our most threatened species, with habitat loss and the reduction of coppicing the main cause of this drastic decline. Being the last remaining population in North Wales, the colony is extremely vulnerable, and it would be a huge shame if we were to lose this beautiful butterfly as a breeding species in the area.

How to get there and see the butterflies:

There is no parking at Eyarth Rocks itself, but there is space for a small number of cars on the layby at Eyarth Bridge (over the River Clwyd) nearby. Just off the A494, the post code is LL15 2NT. Once parked, cross the road at the bridge and walk up to the main road where there is a Butterfly Conservation marked gate. Follow the footpath through and up the steep woodland slopes, until you reach a stile at a field. Head right across the field to a house where the public footpath winds round the back of, and up through the trees again. After a right turn, the path eventually leads to a gate and entrance sign as the area opens up in to the hill top summit. The Pearl-bordered Fritillaries were feeding on the Birds-foot Trefoil and Buttercups by the gate.