In Poland, Odonteus armiger (SCOPOLI, 1772) has been recorded in localities dispersed all over the country. It inhabits meadows adjoining the outskirts of oak forests, brownfields covered with shrubs, scarcely exploited pastures with old single oaks and sunlit oak forests. Thirty new localities of O. armiger have been found in Poland. Their location and distribution indicate that the beetle in question prefers areas situated in ice-marginal valleys of large rivers and is more common in the eastern part of the country. The peak of swarming of this species falls in the second half of June, July, and the first half of August. The beetles in question are most willing to fly on hot and stuffy days, before sunset. They fly slowly, heavily, and low over herbaceous plants. Their larvae probably feed on underground fungi.