On the status of the scarce fritillary <i>Euphydryas maturna</i> (Lepidoptera: Nymphalidae) in Finland

Abstract

The scarce fritillary Euphydryas maturna (L.) is a highly endangered species of butterfly in several European countries. However, in Finland it occurs commonly in the southeastern part of the country and its distribution has remained stable over the past 40 years. The ecology of E. maturna has recently been studied in Finland. In this paper, I review these studies and show that the distribution of the species is tightly linked to its ecology, which differs substantially from the ecology of the same species in central Europe. In Finland, the main larval host plant is Melampyrum pratense (Orobanchaceae), which is common throughout Finland. Euphydryas maturna is restricted to south facing forest edges where the sharp ecotone provides a warm habitat. Larvae need warm microhabitats to be able to grow fast in the spring. Natural forest edges are formed by rocky outcrops, which are common in SE Finland. The distribution of E. maturna coincides with the area where rocky outcrops are common. I suggest that the presence of the granite bedrock close to the surface of the ground largely explains the present distribution of E. maturna in Finland. I also note that the species benefits from clearcuts made in the forests and conclude that E. maturna is not threatened in Finland at the moment.