Ceratina cyanea is polylectic in common with all species of Ceratina. It is the most common and widely distributed member of the genus in the West Palearctic region, and therefore, the list of flowers visited is consequently very large.
British pollen records are as follows: Rhinanthus (Scrophulariaceae); Potentilla (Rosaceae); Ranunculus (Ranunculaceae); Centaurea (Asteraceae); Linum catharticum, (Linaceae); Lotus corniculatus (Fabaceae).
Flowers visited in Britain include: Ranunculus bulbosus (Ranunculaceae); Rubus, Rosa spinosissima (Rosaceae); Echium vulgare (Boraginaceae); Thymus, Clinopodium vulgare, Prunella vulgaris (Lamiaceae); Campanula rotundifolia (Campanulaceae)and Leontodon hispidus (Asteraceae). A specimen has been collected carrying an unidentified orchid pollinium attached to the upper portion of the clypeus.
Terzo (2000) lists: Apiaceae: Daucus carota, Eryngium campestre, E. maritimum, Ferula communis, Heracleum sp., Peucedanum cervaria ; Asteraceae: Achillea millefolium, Acroptilon picris, Calendula officinalis, Carduus sp., Centaurea aspera, C. debeauxi, C. jacea, C. leucophaea, C. paniculata, C. solstitialis, C. stereophylla, Cichorium sp., Cirsium arvense, C. eriophorum, Crepis biennis, C. capillaris, Gaillardia sp., Galinsoga sp., Hieracium pilosella, Hyoseris radiata, Hypochoeris radicata, Inula brittanica, Matricaria recutita, Onopordum illyricum, Picris hieracioides, Senecio jacobaea, Tanacetum vulgare, Taraxacum officinale, Tragopogon ruthenicus, Urospermum dalechampii; Boraginaceae: Echium sabulicola, Echium vulgare; Brassicaceae: Bunias erucago, Rorippa sp., Sinapis arvensis; Campanulaceae: Jasione montana; Caryophyllaceae: Stellaria holostea; Cistaceae: Cistus monspeliensis, Helianthemum nummularium; Convolvulaceae: Convolvulus arvensis; Cucurbitaceae: Bryonia sp.; Dipsacaceae: Knautia arvensis, Scabiosa atropurpurea, S. columbaria; Euphorbiaceae: Euphorbia biumbellata; Geraniaceae: Geranium molle; Hypolepidiaceae: Pteridium aquilinum; Lamiaceae: Calamintha sp., Lavandula angustifolia, Leonurus marrubiastrum, Mentha pulegium, Origanum vulgare, Salvia pratensis, S. verbenaca, Thymus mastichina; Fabaceae: Alhagi sp., Genista hispanica, Glycyrrhiza glabra, Lotus corniculatus, Medicago sativa, Psoralea sp., Trifolium pratense; Liliaceae: Allium angulosum, Asparagus officinalis; Lythraceae: Lythrum sp.; Malvaceae: Althaea officinalis, Malva sylvestris; Oxalidaceae: Oxalis sp.; Plumbaginaceae: Limonium gmelinii; Ranunculaceae: Caltha palustris, Ranunculus bulbosus; Resedaceae: Reseda sp.; Rosaceae: Potentilla bifurca, Rubus sp.; Salicaceae: Salix sp.; Scrophulariaceae: Euphrasia sp., Odontites verna, Veronica chamaedrys, V. persica; Solanaceae: Solanum dulcamara; Tamaricaceae: Tamarix ramosissima; Valerianaceae: Valeriana sp.; Verbenaceae: Verbena officinalis, Vitex agnus-castus.
Balles (1925) adds Fragaria vesca (Rosaceae) to this list, an observation supported by Westrich (1990) who also adds Potentilla neumanniana (Rosaceae). These observations confirm those of Balles (1925, 1927a, 1933), Cavro (1950), Espeso & Gayubo (1988) et Stöckl (1998).
In Spain, Gayubo et al. (1989) also observed the species at Eryngium bourgati, E. campestre (Apiaceae) and Pulicaria paludosa (Asteraceae); Heras & Gayubo (1989) on Foeniculum vulgare (Apiaceae) and Pérez-Inigo Mora & Gayubo (1989), in confusing this species with C. acuta, Carlina sp. and Erygeron canadiensis (Asteraceae).
In Austria, Graeffe (1901) observed it on Bellis perennis and Leontodon taraxacum (Asteraceae).
In Romania, Iuga (1962) cited it among the pollinators of Apple and Pears (Malus sylvestris, Pyrus communis (Rosaceae)).
In the Ukraine, Osychnyuk (1959) observed the species at Barbarea vulgaris (Brassicaceae), Mentha arvensis, Stachys recta (Lamiaceae) and Potentilla obscura (Rosaceae). Pesenko (1974) on Capsella bursa-pastoris (Brassicaceae), Campanula sibirica (Campanulaceae), Caucalis lappula (Apiaceae), Cynoglossum officinale, Myosotis sp. (Boraginaceae), Delphinium consolida (Ranunculaceae), Glycyrrhiza echinata (Fabaceae), Goniolimon tataricum (Plumbaginaceae), Linaria vulgaris (Scrophulariaceae), Melilotus officinalis (Fabaceae), (Boraginaceae), Phacelia tanacetifolia (Hydrophyllaceae), Potentilla reptans (Rosaceae), Sisymbrium sp. (Brassicaceae) and Veronica verna (Scrophulariaceae).
Pawlikowski & Kruszynski (1997) list Centaurea rhenana (Asteraceae); Cardamine pratensis (Brassicaceae) and Fragaria viridis (Rosaceae) as forage sources in Poland.