Sue L writes:
It’s September. I have the window open to the morning. I hear the fluttering of wings and assume it’s a Red admiral as they often come into my room at this time of year. But it isn’t a butterfly….
It’s a moth (it has feathered antennae and when later it closes its wings it does so by folding them down to its back and sides).
Now it opens its wings against the sill. That sudden startling scarlet. It’s a Red Underwing (Catocala nupta). This colour comes from the hind wings and if a predatory bird comes too close the moth will open its wings and confuse the bird just long enough for it to escape.
The moths rest almost invisibly against the bark of trees (particularly willows and poplars which provide food for the caterpillars).
The Red Underwing is found mostly in southern and eastern England.