A collaboration of coast and countryside organisations on The Lizard Peninsula

Catrpillars and their web on devils-bit scabiousBelieve it or not, right now is the best time to survey the population health of one of our most notable butterflies – the marsh fritillary. Admittedly, surveyors will not be looking for butterflies on the wing but they will be taking advantage of the occasional sunny but not too warm day to spot basking caterpillars.
This spring, ecologists from the Environmental and Sustainability Institute (ESI) at Exeter University are undertaking a survey of Marsh fritillary butterfly colonies on The Lizard. This attractive butterfly is one of the most rapidly declining butterfly species in Europe, principally because the damp meadow habitats it frequents have been increasingly drained for agriculture. Scrub encroachment through lack of management and climate change are also factors in its recent demise.

Marsh fritillary caterpillar,( Marsh fritillaries depend on just the right level of grazing)There are probably only a handful of colonies remaining on the Lizard, with core populations restricted to areas where the hostplant, Devil's-bit Scabious, grows in abundance –unimproved grassland and heathland. The aim of the survey is to identify where colonies remain, and to investigate how best to manage existing and potential sites to ensure that Marsh fritillaries remain a feature of the Cornish landscape. You can read more about the marsh fritillary here.

 Scabious in bloom in August A banquet for a marsh frit caterpillar 

The larvae are relatively easy to spot, they are all black and more importantly they feed communally, often forming a black mass of up to 150 around Devil's-bit Scabious (see photo). They will have survived the winter in a dense silken web low in the vegetation, having hatched from eggs last summer. If you see some larvae whilst out walking over the next month, please could you inform Robin Curtis at ESI (This email address is being protected from spambots. You need JavaScript enabled to view it.), providing a date, location and preferably a photo. All records will remain confidential, and this information will contribute to conserving one of Cornwall's rarest and most attractive butterflies.
Marsh Fritillary Table

Published: Mar 2015
Author: Robin Curtis