It's been great to have some warm sunny weather after what has been quite a wet late spring, early summer. This has been perfect for the emergence of thousands of insects from the fluttering butterflies to the humming hoverflies and not forgetting the pestering midgies! Some species, such as meadow brown and ringlet butterflies can be abundant and seen very easily as you walk along grassy paths but others take a little more planning and effort to find.
One such species is the Welsh clearwing, which is a daytime flying moth that only breeds on mature birch trees. It's conservation status is: UK BAP species, Red Data Book and Priority species in Wales. Here at Lake Vyrnwy we have had a population since 1992, but in recent years signs of breeding have apparently reduced. The adults like to spend most of their time at the top of trees and are therefore rarely ever seen, usually only when emerging from their larval casing protruding from the bark of the birch tree, making them hard to survey. These larval cases, known as exuviae once the adult has emerged, can be found on birch trees and is generally what we look for when surveying for this moth.
Welsh clearwing coming into pheromone trap by Gavin Chambers
However, this year the Montgomeryshire Moth Group decided to buy some pheromones to help lure the adult moths in and therefore get a definitive result of there presence. As we are the key site in Montgomeryshire for this clearwing species, the moth group kindly lent us the pheromone and equipment to try on site. So on a warm sunny afternoon we headed to the site and got the pheromone set up, it didn't smell of anything and therefore it was hard to tell if it was actually working! After a 20 minute wait a small dark insect suddenly came into view, hovering and darting about in front of us. Then came the flash of orange as it turned and started hovering close to the pheromone. We had attracted a Welsh clearwing!
Welsh clearwing by Gavin Chambers
We were able to catch it with a butterfly net and get great views of this stunning moth and be able to see why this group of moths gets its name of clearwing. It was also kind enough to sit for a few photos before quickly taking off in the warm sunshine. Within another 10 minutes we were watching another 2 buzzing around the pheromone. On Wednesday we had another go in even better conditions and were graced by the presence of 8 Welsh clearwing! Finding these adults is a great success and shows that our management is working and that we must continue to enhance and expand their precious habitat.
Ashworth's Rustic by Gavin Chambers
Another important species for the reserve is the Ashworth's Rustic moth. Like the majority of moths they are active at night and fortunately this species does get attracted to light traps. So on Saturday night myself and a member of the Montgomeryshire moth group set up a couple of 125w mercury vapour moth traps on site and waited to see what came in. In total we recorded 55 species (including 14 micros) which to our delight also included 6 Ashworth's Rustic by 1am when we started to pack up. Despite the larvae having a common foodplant (common rock-rose, heather foxglove and other species) this moth is restricted to slate and limestone hills of North Wales. We are currently in the process of planning some woodland work in the area they inhabit and therefore we must understand what we have and how best to minimise the disturbance to them.
Gavin Chambers, Warden
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