Oligolectic on Asteraceae with a preference for Carduoideae; species of the Cichorioideae and the Asteroideae are exploited as pollen sources as well (based on 21 pollen samples from 5 different localities and on field observations). Eighteen pollen loads consisted exclusively of pollen of Carduoideae (Centaurea and/or thistles), while the other three loads additionally contained pollen of Cichorioideae (n = 2) and Asteroideae (n = 1), suggesting that Osmia picena exhibits a preference for Carduoideae as pollen hosts, but occasionally also exploits flowers of Cichorioideae and Asteroideae(Müller, 2018).