Super Rare Moth at Westonbirt

Volunteering at Westonbirt Arboretum is something that I love to do… but some days are extra special!  Yesterday, a very rare Clifden Nonpareil (also known commonly as a Blue Underwing) moth was discovered in one of the polytunnels at Westonbirt.  Only a handful of these migrant moths are spotted in the UK each year and I was one of only a handful of people lucky enough to see and photograph this beauty.


The first thing you notice about the Blue Underwing is its size.  With a wingspan approaching 100mm, it is one of the largest moths to be found in the UK. At first, with its hindwings tucked in, it looked large but not particularly colourful.  Its forewings have intricate patterns, that appear mainly brown when in shade and mainly grey when in light – camouflaging it perfectly to blend in against stone walls or tree bark.

Catocala fraxini – Westonbirt Arboretum

However, once its hindwings are visible, you see the charismatic violet-blue bands that give it its name.  Wow!


It may be unusual to see spectacular colour in a moth at Westonbirt – but spectacular colour from trees is a very common sight here every Autumn.