September Thorn Ennomos erosaria
([Denis & Schiffermüller], 1775)
Although superficially similar to several other of the autumn-feeding 'Thorns', this species is generally much plainer in appearance.
It is reasonably common in England and Wales, becoming scarcer in the north of England and Scotland, and is rare in Ireland.
July to October is the main flight period, when the species is often attracted to light.
The caterpillar closely resembles a small twig, and feeds on oak (Quercus), birch (Betula) or lime (Tilia).