Black Arches

Lymantria monacha

The black arches or nun moth is a small Palaearctic moth. It is considered a forest pest. Source

Where it is now

In the last 8 weeks this insect was recorded 6 times across 2 areas (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 22°C (typically 21 to 23°C, from 5 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 49°N in July to 63°N in August, about 1,500 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.