This study aims to get a better understanding of the oviposition-behaviour of the butterfly Marsh Fritillary (Euphydryas aurinia), in the area Bälsalvret on the Island of Gotland. The study may provide helpful information to aid the conservation of the species in the area and also provide overall knowledge about the female’s preferences when it comes to choosing microhabitat and host plant for their eggs. The analysis of the microhabitat preference for oviposition by the Marsh Fritillary showed that eggs were predominantly laid on large-sized host plant individuals with a warmer microclimate; with a preference for the rosette diameter, the length and the width of the leaf and the number of Succisa pratensis individuals in the vicinity. This indicates that the female’s priority is to place the eggs at the most optimal place for their offspring’s survival and growth.

The purpose of the study was to provide further knowledge about if the total amount of solar radiation during the marsh fritillary’s (Euphydryas aurinia) period for larvae development (April 15th – May 15th) and/or flying period (June 1st – June 30th) influenced the average of larvae colonies in the autumn at 12 sites in Dalarna County. Among increased temperatures, global climate models also predict an increased amount of solar radiation and a decrease in cloudiness in northern Europe, as a result of the climate changes. The marsh fritillary has declined rapidly, especially in the Northern of Europe and are in Sweden red-listed as vulnerable (VU). The marsh fritillary is a univoltine species who are dependent on open, sunny, and moist semi-natural grasslands with the hostplant devil’s bit (Succisa pratensis). The data over solar radiation was received from SMHI and had been measured in Borlänge over the last 14 years. The data over the number of larvae colonies was received from Länsstyrelsen Dalarna and had been measured over the last 15 years. The linear regression analysis for both the period of larvae development (p=0,58) and the whole period (p=0,07) indicates that during those periods the solar radiation did not influence the average of larvae colonies. However, the total amount of solar radiation during the flying period (p=0,02) influence the average of larvae colonies during the autumn.