Species Details

ABH: 70.236

BF: 1915

Family: Geometridae

Subfamily: Ennominae

Taxon: Ennomos erosaria

Authority: ([Denis & Schiffermüller], 1775)

Vernacular: September Thorn

Account: Common in woodland, parks and gardens throughout much of England, spreading into Scotland, a species of conservation concern under the UK Biodiversity Action Plan The most likely confusion species is August Thorn E. quercinaria, which has the antemedian fascia (the line nearest the base of the wing) acutely angled at the costa (almost straight in September Thorn). Larva feeds on Oak, Lime, Birch and Beech, over-wintering as an egg.

Accounts provided by and used with the kind permission of Mike Wall, Hampshire County Moth Recorder. These will in due course be gradually replaced with species accounts with a Surrey context.

Wingspan: 38 — 42 mm

Surrey Flight Period: 16 Jun (2022) — 20 Oct (1950)

The flight period of overwintering adults are not given. See the flight chart below the distribution map.

Foodplant: Betula sp. (a birch), Quercus sp. (an oak), Tilia sp. (a lime).

Foodplant accounts are from the HOSTS database — Natural History Museum, London, UK. (CC0).

Status: Near Threatened (NT)

UK BAP: BAP(R)

WCA:

Click here to view the full geology map of Surrey.

Verification Grade: 2 — Care needed to identify, an image may be required 🤔
Further Information: https://www.ukmoths.org.uk/species/ennomos-erosaria/
Statistics

* Based on adult records only.

Records: 696

Individuals: 651

Earliest Year: 1883

Latest Year: 2025

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