Shown here is one of the rarest moths in Britian, the Rosy Marsh Moth (Eugraphe subrosea), which can be seen at Cors Fochno in Dyfi NNR. (Picture courtesy of Rob Petley-Jones, Natural England.)
Wales has such a huge diversity of wildlife with so many great places to see birds, plants and mammals that it could hardly fail to be a good place to see insects, too. True to form, then, we have numerous nature reserves that are home to some of the rarest and most interesting insects species found in Britain. At Rhos Llawr Cwrt NNR, for instance, there are recordings of up to 20,000 Marsh Fritillaries in good years, which makes it the UK's premier site to see these lovely butterflies.
Cors Fochno (Borth Bog) at Dyfi NNR has a small population of the Rosy Marsh Moth (pictured, right) thought to be extinct in the UK for more than 100 years until quite recently. In Pengelli Forest we have the Oil Beetle (Meloe proscarabeus,) which looks more like a louse (and indeed it was classified as such for many years) than a beetle.
Aberbargoed Grasslands NNR
Cors Fochno - Dyfi National Nature Reserve
Meirionydd Oakwoods National Nature Reserves
Pengelli Forest National Nature Reserve
Merthyr Mawr National Nature Reserve
Morfa Dyffryn National Nature Reserve
Rhos Llawr Cwrt National Nature Reserve
Bryn Pydew North Wales Wildlife Trust Reserve
Cors y Llyn National Nature Reserve
Gregynog National Nature Reserve