Polylectic. British pollen sources poorly known, but the species is presumed to be polylectic. Pollen collection from Stachys palustris (Lamiaceae) has been observed in Surrey by D.B. Baker (pers. comm.).
Species visited in Britain include: Lotus corniculatus, Lotus uliginosus (Fabaceae); Linaria purpurea, Linaria repens, Digitalis (Scrophulariaceae); Thymus, Stachys officinalis, Stachys palustris, Stachys sylvatica, Stachys lanata, Ballota nigra, Lamium purpureum, Lavandula, Nepeta cataria, Marrubium vulgare, Rosmarinus officinale, Teucrium scorodonia, Ajuga (Lamiaceae); Campanula (Campanulaceae); Centaurea (Asteraceae).
In Germany (Westrich, 1989), favours zygomorphic flowers: Lotus corniculatus, Coronilla varia, Ononis repens, Ononis spinosa, Medicago sativa (Fabaceae); Stachys recta, Stachys byzantina, Stachys palustris, Stachys officinalis, Ballota nigra, Salvia sclarea, Teucrium chamaedrys, Lamium purpureum, Galeopsis angustifolia (Lamiaceae); Digitalis purpurea, Digitalis lanata (Scrophulariaceae).
In Finland, 64 species (placed in 9 families, but with a preponderance of Lamiaceae, Scrophulariaceae and Fabaceae) are recorded by Elfving (1968).
Pollen analysis (Muller, 1996) revealed the following pollen sources: Fabaceae, Lythraceae, Boraginaceae, Lamiaceae, Scrophulariaceae and Asteraceae. Muller cites Ononis arvensis, Ononis spinosa (Fabaceae); Calamintha nepeta, Stachys cretica, Stachys recta, Teucrium scorodonia (Lamiaceae); Antirrhinum majus, Digitalis lanata, Digitalis purpurea, Linaria genistifolia, Misopates orontium (Scrophulariaceae) as pollen sources in Switzerland and Italy.
Pawlikowski & Kruszynski (1997) list Echium vulgare (Boraginaceae) as a forage source in Poland.
Stanisavljević, 2000, copying Banaszak & Romasenko,1998 lists Stachys, Salvia, Lamium, Ballota, Betonica (Lamiaceae); Lotus, Cytisus, Medicago, Coronilla (Fabaceae).
Matache & Ban (2006) state that the species is polylectic, and uses Fabaceae and Lamiaceae as forage sources.
Weissmann et al (2017)state that on the Azores, the species has a preference for Lamiaceae, where the females also collect plant hairs for their nest, also observed on Lotus corniculatus (Fabaceae).