Oligolectic on Onosma (eg O. javorkae) (Boraginaceae) and possibly closely related genera (A. Müller, unpublished, based on 42 pollen samples from 27 different localities and on field observations).
According to Ducke (1900) and Graeffe (1902), Osmia apicata was only observed on Onosma echioides (Boraginaceae). The oligolecty was confirmed by Teppner (1996) and A. Müller (2011). Teppner (1996) observed Osmia apicata on Onosma helvetica, O. heterophylla and O. stojanoffii in Greece.