Host-ant specificity of Maculinea alcon, an endangered obligatory myrmecophilous lycaenid butterfly, was studied at two sites in southern Poland (Swietokrzyskie Mts near Kielce). M. alcon larvae and pupae were found in nests of both Myrmica vandeli and M. scabrinodis, which is the typical host in Poland and Southern Europe. To our knowledge this is the first record of M. vandeli as a host of M. alcon. Our results show that M. scabrinodis and M. vandeli are about equally suitable as hosts. We hypothesize that both host ant species are closely related and have similar chemical profiles, and that the M. alcon "scabrinodis-vandeli" populations we studied belong to the M. alcon "scabrinodis" race. More than half of the M. alcon pupae, both from M. vandeli and M. scabrinodis nests, were parasitized by a single wasp species of the genus Ichneumon, which also suggests that the cuticular chemistry of the two ant species is similar. not entered - Ichneumon is questionable none