A motorist driving through the Black Mountains on the evening of Saturday 25th April might have spotted seven shadowy figures ascending a steep hillside as dusk descended.
The motorist would probably never have guessed that the intrepid climbers were in search of the caterpillars of a rare moth. The Silurian has intrigued Lepidopterists since its discovery in the hills near Abertillery (Blaenau Gwent) in 1972.
Since then we have come to understand more about its distribution, which includes the eastern side of the Black Mountains as well as another hill further south. The moth breeds high on the hills, making light trapping impractical unless there is a handy track to transport the heavy gear up the mountain.
Much of the work has therefore involved looking for larvae, which requires only a torch. The searches have to be carried out at night, when the caterpillars emerge from deep carpets of moss to feed on the unfurling leaves of Bilberry.
This year we searched a new area near the northern escarpment of the Black Mountains. By the time we descended at midnight the temperature had tumbled to 2°C, but we were warmed by the fact that we had seen a record 91 Silurian larvae.
Not only this, but these were the highest altitude and also the most northerly Silurians ever found in the UK. Even more exciting was that three of them were feeding on Crowberry rather than the usual Bilberry, so we gained some new information about the ecology of the moth too.
Surveys for larvae have been ongoing for six years, with a great deal of help from Butterfly Conservation volunteers. In this time the known range of the moth has increased from five to 24 square kilometres. Well worth getting cold feet for!
by George Tordoff, Monitoring Ecologist (Wales)