Marsh Fritillary - Life Cycle

Life Cycle

The eggs are laid in groups on the underside of the leaves in May and June. Up to 350 are laid in a single batch. They turn from pale yellow when first laid, turn bright yellow, then crimson, and finally to dark grey just prior to hatching. The caterpillars hatch from the end of June onwards. The young caterpillars live in communal webs that are spun across the foodplant and these become conspicuous by the end of August. In the autumn they make stronger webs, closer to the ground usually within a dense grass tussock, where they will start to hibernate. In the spring the caterpillars start to disperse from their communities after their last molt. They change colour from brown to black and may be occasionally seen basking in the sun. They need to be warm in order to eat. The caterpillars are liable to be attacked by the parasitoid wasp Apanteles bignellii, especially in warm spring weather. Pupae form from mid April, low down deep within grass tussocks or dead leaves. Adults emerge from mid-June to mid July.