The peacock butterfly (Aglais io) is easy to identify by the four blue eyespots on its wings. It is a new species in Finland that first established a population here in the 1970s. It was unable to overwinter in Finland until it adapted to wintering in outbuildings and garages. It has since gone on to become one of the most common butterfly species in Finland. The fairly large, black larvae feed exclusively on nettles. This kind of species that only feeds on a single plant species is called a monophage.
Photo Helsinki City Material Bank, Marianne Saviaho.