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Marsh Fritillary caterpillars - copyright  Pete Eeles Marsh Fritillary Report Card

Over the last two years, researchers based at the Environment and Sustainability Institute, University of Exeter have been undertaking surveys and research on the Marsh fritillary on the Lizard. Our main conclusions are that this butterfly remains extremely localised (occurs on only a handful of sites) and vulnerable to extinction. We have recently produced a report card which summarises our knowledge about the Marsh fritillary, and how best to manage the Lizard landscape for its continued survival. This document is uploaded onto the website, so please take time to read it and hopefully it will inspire you to go out and look for the autumn webs, which while are not as attractive as the adult butterflies are interesting nonetheless.

Indeed, it is the many months spent in the larval stage which is the key to the survival of many butterflies, with Marsh fritillary larvae currently devouring as much Devil’s-bit scabious as possible before the larvae moult in September (changing in colour from brown to black) stimulating the larvae to build a hibernaculum in which they will spend the winter months before resuming feeding early the following year. These larval webs are quite distinctive, looking a bit like large, white spider webs covering Devil’s-bit scabious plants but on closer inspection clearly containing caterpillars (see photographs) and we will currently be undertaking an autumn survey with the aim of assessing the distribution and population size of the remaining colonies on the Lizard – so if you find an autumn web somewhere that you think we may not know about please let us know (please contact This email address is being protected from spambots. You need JavaScript enabled to view it. with an OS grid reference).

Marsh Fritillary caterpillars - Autumn web Marsh Fritillary caterpillars - Autumn web
Autumn web - copyright  Pete Eeles Autumn web - Steve Townsend


Several University of Exeter students have assisted with research, and the following article is written by Amber Nichols who conducted surveys and research on the Lizard during 2016 as part of her MSc in Conservation and Biodiversity.


Unfortunately, before we get to her article, we must report the untimely death of Ilkka Hanski, a professor in butterfly biology at Helsinki University, Finland who died in early May. He mainly studied the Glanville fritillary (a close cousin of Marsh fritillary) on the Aland Islands, a Finnish archipelago. His main contribution to butterfly conservation was to emphasise the importance of landscape scale conservation through metapopulation theory, highlighting the importance of linking separate populations through dispersal – and this is exactly what we are attempting to do to ensure the survival of the Marsh fritillary on the Lizard.

Marsh fritillary Survey 2016

There is something really special about the Marsh fritillary butterfly (Euphydryas aurinia). Utter its name to those enthused by natural history and you’ll find out. This checkerspot is one of our country’s most endangered butterflies having suffered considerable decline due to the rise of intensive agriculture, leaving populations few and far between. Yet against all odds populations still persist on the Lizard Peninsular, marking this area as an important stronghold on a national level.

Marsh Fritillary
Marsh Fritillary © Amber Nichols

Efforts to monitor the Marsh fritillary on the Lizard were continued this spring, building upon previous surveys undertaken over the past few years by researchers at the University of Exeter’s Environmental and Sustainability Institute (ESI). Surveyors looked for conspicuous larval webs spun close to the ground, near their food plant Devil’s-bit scabious (Succisa pratensis). Populations were identified at eight sites; four of these sites supported marsh fritillary in 2015, whilst the other four are either new sites or confirm older records. Unfortunately, larval webs were not found at one site which was occupied last year.

Marsh Fritillary caterpillars
Marsh Fritillary caterpillars © Amber Nichols

Larval web numbers were sustained or increased across many sites in comparison with the previous year. Whilst these findings are reassuring, we must acknowledge these results within the context of how Marsh fritillary populations persist. Populations are known to greatly fluctuate among years; seemingly flourishing populations often experience crashes attributed to various factors including the weather, rates of parasitism (by parasitoid wasp species - genus Cotesia), and unfavourable changes in the condition of its habitat. Although it is infeasible to control the weather or its parasitoid, we can aim to optimise the quality of the butterfly’s habitat to help ensure quick re-colonisation should populations drop.

So what is a ‘high quality’ habitat? To address this question, our surveys measured a range of aspects about their occupied habitat (such as the structure of vegetation and topography), enabling us to build a clearer picture of their habitat requirements specifically here on the Lizard. In turn this knowledge will contribute to the overall mission of implementing sound land management practices, giving the stunning Marsh fritillary the best possible chance of remaining resident in our landscape for the future.

Published: Aug 2016
Author: Amber Nichols (MSc Conservation and Biodiversity student)