As this is a cleptoparasitic species, all flower visits will be for nectar only.
Lieftinck (1969) summarising previous authors, lists Vicia dasycarpa (Fabaceae); Thymus sp. (Lamiaceae) and Cistus villosus (Cistaceae) as nectar sources.
Nectar visits are known from Vicia villosa (Fabaceae)(pers. obs)