September Thorn - Ennomos erosaria


Wingspan 30 to 35mm. Pale yellow with dark cross lines. Although superficially similar to several other of the autumn-feeding 'Thorns', this species is generally much plainer in appearance.

Similar Species

It is very similar to the August Thorn. Perhaps the easiest way to distinguish them is that the September Thorn has all-yellow legs whilst the August Thorn has 'knee socks' where the lower part of the legs is whitish.

The August Thorn also has the line nearest the base of the wing acutely angled at the costa whilst this is almost straight in the September Thorn.

Identification difficulty

Well wooded areas.

When to see it

July to October is the main flight period, when the species is often attracted to light.

Life History

The caterpillar closely resembles a small twig, and feeds on oak, birch or lime.

UK Status

It is reasonably common in England and Wales, becoming scarcer in the north of England and Scotland, and is rare in Ireland. In a recent survey to determine the status of all macro moths in Britain this species was classified as common.

VC55 Status

Fairly frequent but not common in Leicestershire and Rutland. L&R Moth Group status = B (scarce resident or restricted distribution or regular migrant).

70.236 BF1915

Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map