A common and distinctive, large moth, which is on the wing from May to July. The striking caterpillars are found on willow from July and can strip entire stems of leaves. Before pupating, they spin a hard cocoon, incorporating wood chewed by the larva, on a tree trunk or post.

References: 
Leverton, R. & Cubitt, M. (2024). The Larger Moths of Scotland.
Waring, P. & Townsend, M. (2018 third edition). Field Guide to the Moths of Great Britain and Ireland.