As this is a cleptoparasitic species, all flower visits will be for nectar only.
Flowers visited as nectar sources (Else in prep.): Brassica, Cheiranthus cheiri (Brassicaceae); Anthyllis vulneraria (Fabaceae); Prunus, Malus (Rosaceae); Rosmarinus, and Glechoma hederacea (Lamaceae).
Celary (1990) list the following nectar sources in Poland: Ajuga sp., Glechoma hederacea, Lamium sp. (Lamiaceae); Taraxacum officinale (Asteraceae)
Mavromoustakis (1948; 1951) reports nectar foraging at Bellevalia (=Hyacinthus) trifoliatus (Hyacinthaceae); Anchusa hybrida (Boraginaceae); Vicia cracca elegans (Fabaceae); Salvia sp. (Lamiaceae) in Cyprus.