As this is a cleptoparasitic species, all flower visits will be for nectar only.
Celary (1995) lists Euphorbia cyparissias (Euphorbiaceae) and Lamium purpureum (Lamiaceae) as nectar sources in Poland. Mavromoustakis (1953) reports visitation to Calendula persica, Cichorium intybus (Asteraceae) in Cyprus.