As this is a cleptoparasitic species, all flower visits will be for nectar only.
Flowers visited in UK (Else & Edwards, 2018): Ranunculus (Ranunculaceae); Vicia cracca (Fabaceae); Chamerion (Onagraceae); Scabiosa (Dipsacaceae); Senecio and Cirsium vulgare (Asteraceae).