Marsh Fritillary

The marsh fritillary is listed on Annex 2 of the European Habitats Directive 92/43/EEC

Suitable habitat for this species includes damp, flower-rich grasslands, dunes, heaths, fens and bogs where there is an abundance of devil’s-bit scabious (Succisa pratensis), the food plant of the caterpillar in Ireland and Britain. To establish the extent of suitable habitat for marsh fritillary our surveyors can map the occurrence of devil’s-bit scabious on a development site.

If present on a site the standard method of monitoring marsh fritillary populations is to count the larval webs. Due to the different development stages of the larvae, only occupied webs should be recorded. Larval web surveys should be conducted in late August and September when the webs are most visible. Statutory Nature Conservation Organisations also prefer that a survey of adult butterflies also takes place between May and July, as this can aid identification of web locations.

Adult butterflies only fly in warm, sunny conditions, so visits should only be undertaken in favourable weather conditions between 10.30 and 16.30. The presence of adults confirms that there is a marsh fritillary breeding colony in the area. The results of the surveys are then presented in a written report which will include large scale maps showing details of the walked transects. The locations of adult marsh fritillary sightings and all larval webs will be mapped using handheld GPS recorders.