Marsh Fritillary Reinforcement Project

In March 2021, INCC and volunteers took (under license) 80 Marsh Fritillary caterpillars from several locations across Rhondda Cynon Taff and Caerphilly County Borough Councils. The caterpillars were reared in captivity through to pupation until adult butterflies. Whilst in the rearing pens, the butterflies laid thousands of eggs.

This new generation of caterpillars would mark the return of the Marsh Fritillary butterfly to Llantrisant Common, South Wales. It had been well over 20 years since Marsh Fritillary were recorded at the common, but in September 2021, several larval webs were translocated to the site to see out the winter in hibernation. It was a worrying time for INCC, as these captive reared caterpillars now had to fend for themselves in a completely new habitat. We wouldn’t know how well they would do until the following spring when they emerge from hibernation on sunny days. Surveys of the Common in February 2022 revealed dozens of Marsh Fritillary caterpillars. They had survived hibernation.

Marsh Fritillary caterpillars seen through thermal camera.

During the flying season of 2022, hundreds of Marsh Fritillary butterflies were seen across the common. Local school children and volunteers who have helped the project at every stage were able to see all their hard work up close. Soon after the first butterflies were seen on the wing, they started mating and laying eggs on the Devil’s-bit Scabious plants.

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