Small Fan-footed Wave

Idaea biselata

The small fan-footed wave is a moth of the family Geometridae. The species was first described by Johann Siegfried Hufnagel in 1767. Source

Where it is now

In the last 8 weeks this insect was recorded 4 times across 1 area (each area is a 5 degree square).

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Movement and weather

Each season it is first heard regularly where daytime highs are around 20°C (typically 20 to 21°C, from 6 areas). That holds across 20° of latitude, which suggests its timing follows temperature more than the calendar.

Over the weeks it was present in the past year, its centre in Europe ranged from 50°N in June to 61°N in August, about 1,300 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.