Three-humped Prominent Notodonta tritophus
([Denis & Schiffermüller], 1775)[Synonyms: Tritophia tritophus]
Wingspan 45-55 mm.
A very rare immigrant, having been recorded only a handful of times in the last hundred years, almost all at coastal localities in the south.
The English name refers to the caterpillar, which has three rearward-pointing humps on its back.
The larva has not been recorded in Britain since the 19th century, but in Europe it feeds on poplar (Populus), willow (Salix) and birch (Betula).