Background: The scarce fritillary Euphydryas (Hypodryas) maturna (L.) is included in the Habitats Directive's Annexes II and IV(a). Therefore, it is crucially important to be able to define the habitat and breeding places of E. maturna in a correct and unbiased way. New information: Data on a previously unknown pre-diapause main host plant, the small cow-wheat (Melampyrum sylvaticum L.), of Euphydryas maturna in Finland is presented.