Main: (Geometridae / Ennominae)
70.236 [B&F: 1915] September Thorn (Ennomos erosaria) ([Denis & Schiffermüller], 1775)

 

Notes: Common in woodland, parks and gardens throughout much of England, spreading into Scotland, a species of conservation concern under the UK Biodiversity Action Plan. In Hampshire and on the Isle of Wight Common and widespread. Although the flight-time histogram shows a smooth curve of emergence, in most years there are two peaks, one in July and another, usually smaller, in September. Wingspan 38-42 mm. 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.

Flightime guide
JFM AMJ JAS OND

Records Received By Year

% of total records
Max records: 248
90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13

Percentage of Total Records

Total records
Max Percentage: 0.16007826
90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13

Phenology - Adult Records

Max records: 279
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Phenology - Larval Records

Max records: 1
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Distribution Map

Historical distribution at tetrad resolution
Click for density map

Record Density

As above but the larger the symbol, the greater the number of records
Click for distribution map
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