Oligolectic on Asteraceae (Amiet et al., 2004). I. Cross (2011, in litt.) reports "At the time of year we visited pollen sources were few and far between. Bees were found in a dried arroyo at Dittrichia (Asteraceae) and along a woodland edge at another, unidentified yellow composite (possibly Senecio gallicus). It was interesting how the only other, abundant yellow composite, Carlina racemosa wasn’t used at all. It seems that flower structure and not just colour is what attracts these small bees: with the rather longer florets of Carlina of no use compared with the shorter tube florets of Dittrichia and on the disc of Senecio."
Mavromoustakis (1952) reports visitation to Dittrichia (=Inula) viscosa, Inula crithmoides, Pulicaria dysenterica, Carthamus boissieri (Asteraceae); Kickxia (=Linaria) elatine (Plantaginaceae); Limonium (=Statice) sp. (Plumbaginaceae); Eryngium creticum (Apiaceae) in Cyprus
In Britain H. rubicola females have been seen visiting Pulicaria dysenterica, and Picris heiracioides. This bee is oligolectic on Asteraceae (Amiet et al., 2004) and apparently prefers to forage on yellow-flowered species of Senecioneae and Inuleae. In Portugal and Spain early broods visit a variety of yellow Asteraceae including Helichrysum stoechas, and late broods are frequently seen visiting Dittrichia viscosa (Asteraceae)(Cross & Notton, 2017).