As this is a cleptoparasitic species, all flower visits will be for nectar only.
Westrich (1989) lists the following plant species as nectar sources: Salix (Salicaceae); Tussilago farfara, Taraxacum officinale (Asteraceae).
Smit (2004) lists Salix sp. (Salicaceae) as a nectar source.
Celary (2007) lists: The species visits flowers of Taraxacum officinale, Tussilago farfara (Asteraceae); various species of Salix (Salicaceae) and Thlaspi alpestre (Brassicaceae) (Celary 1995; 2007)