I was down at the Ballachuan Nature Reserve today with several other volunteers, David Croucher and the Scottish Wildlife Trust Reserve Manager, Simon Jones to try and find evidence of the Marsh Fritillary butterfly.
The butterfly flies in late May and June. The female then lays batches of eggs on the underside of Devil’s-bit Scabious leaves. From July until late September the black, spiny caterpillars feed together on Scabious leaves inside a silken white web.
During the winter they hibernate together in this small web, hidden in the sward. The caterpillars emerge in February or early March and separate; sometimes wandering several metres to find fresh Scabious leaves. By late April–early May the caterpillars change in to a chrysalis and emerge as adult butterflies 2–3 weeks later.
It was these webs we were searching for amongst the damp, flower-rich grasslands of the marsh. Grassland which contains a mixture of rushes, heather, long tussocky grass and the plentiful Devil’s- bit Scabious.
It was a glorious day, but hard work stumbling amongst the tussocky grass and marsh but we were fortunate to find approximately fifty of these silken webs, with their small black caterpillars searching for food.
It will be interesting to return on a warm sunny day next June to organise a transect count of the butterflies to see how many have survived the life cycle.