The Marsh Fritillary was once widespread in Britain and Ireland but has declined severely over the twentieth century, a decline mirrored throughout Europe. Its populations are highly volatile and the species probably requires extensive habitats or habitat networks for its long term survival.
The Marsh Fritillary butterfly requires areas of tussocky damp grassland which includes Devil’s Bit Scabious; the foodplant required by its caterpillars. The species requires grassland that has not been too heavily grazed and in late summer, the caterpillars spin webs in the grassy tussocks.
The number of Marsh Fritillaries on a site are never constant; it will be abundant some years, but a few years later there may be very few. They depend on having a number of suitable grassland sites in the local area so that the adults can move from site to site as the populations change and as they seek to avoid predators. One of the key areas for Marsh Fritillaries in the National Park is around Penderyn in the south of the Park.
For more information on the Marsh Fritillary and its habitat requirements see Butterfly Conservation’s website – click here.
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