As this is a parasitic species, all flower visits will be for nectar only.
In Spain, Ornosa & Ortiz-Sánchez (2004) list the following plant families as providing forage: Asteraceae and Scrophulariaceae.
Celary (1989) lists the following nectar sources in Poland: Epilobium sp., (Onagraceae); Knautia arvensis (Dipsacaceae); Jasione montana (Campanulaceae); Cirsium sp., Centaurea sp. (Asteraceae)