The violet copper (Lycaena helle) is one of the most endangered butterflies in Europe, with a population pattern of steady decline despite consevation efforts. The main threat to the species is believed to be habitat fragmentation and loss due to changes in land use practices. In order to direct conservation efforts toward the areas where they make the most difference, we need to better understand the ecological needs of the species, on both local and meta population levels. Since habitat quality is a crucial factor for succesful reproduction, increased knowledge of the species’ habitat requirements is of utmost importance. In this study, I investigated whether there is a correlation between the share of hatched eggs and leaf size and shape of the host plant Bistorta vivipara, which vary greatly depending on the level of solar exposure. In the summer of 2022, I searched for eggs and larvae of L. helle on leaves of B. vivipara on three rich fens situated in the municipality of Ånge, Västernorrland County. All leaves with eggs and/or larvae were photographed next to a ruler in order to measure length and width, and the total number of eggs as well as the number of hatched eggs were documented. I then divided the leaves into four classes based on the length/width ratio. Chi-square tests were conducted on the share of hatched eggs per leaf class and locality. The results showed a tendency for a larger share of hatched eggs than expected in leaf class 2, and a smaller share of hatched eggs than expected in leaf class 3, but the results were non-significant. Similarly, the results showed a tendency of a larger share of hatched eggs than expected on locality 2, and slightly smaller shares of hatched eggs on localities 1 and 3, but these too were non-significant. In conclusion, more studies are needed in order to better understand how we can conserve this threatened species.