September Thorn

Ennomos erosaria

Ennomos erosaria, the September thorn, is a moth of the family Geometridae. The species can be found in the Palearctic realm in western Europe and from central Scandinavia. Its range extends to the northern Mediterranean and east to the Caucasus and Russia. It is widespread in mixed and deciduous forests in Europe. The south eastern occurrence reaches Turkey and the Caucasus. The main habitat is dry deciduous forests and parks. In the Southern Alps, the species rises to an altitude of about 1600 metres. Source

Where it is now

In the last 8 weeks this insect was recorded 298 times across 6 areas (each area is a 5 degree square).

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Movement and weather

Over the weeks it was present in the past year, its centre in Europe ranged from 48°N in June to 58°N in August, about 1,200 km apart.

Arrival dates

The week it was first heard regularly in each region, after at least six weeks away. Dates differ from south to north, so a region has a range.

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Figures are effort corrected and come from automatic sound identification, which makes mistakes. How this is measured and how it compares with human observers.