St Marks Fly

Bibio marci

Bibio marci or St. Mark's fly or hawthorn fly, is a species of fly from the family Bibionidae. It is found across much of Europe. Their common name comes from the fact that the adults usually emerge around St Mark's Day, 25 April. Source

Where it is now

No records in the last 8 weeks. It may be out of season where the observers and sensors are.

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Movement and weather

Each season it is first heard regularly where daytime highs are around 13°C (typically 11 to 14°C, from 5 areas).

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.