Caterpillars munch on a range of plants including:
Adult moths take nectar from the flowers (called catkins) of willow trees.
In autumn, caterpillars turn into a chrysalis in an underground cocoon, where they will stay for the whole winter until the adult moth emerges the following spring.
There is even more about this species on the main Butterfly Conservation website
This moth gets its name from the dark shape on its wing, which looks like the Hebrew letter ‘nun’.