Polylectic: British pollen sources not known but known to visit Potentilla (Rosaceae), Veronica chamaedrys (Scrophulariaceae) and Leontodon (Asteraceae).
In Germany, pollen records from: Brassica napus, Cardamine pratensis, Sinapis alba (Brassicaceae); Melilotus alba, Trifolium repens (Fabaceae); Potentilla verna, Rubus fruticosus (Rosaceae); Jasione montana (Campanulaceae) and Tanacetum vulgare, Taraxacum officinale (Asteraceae) (Westrich, 1989).
Ebmer (1969) lists the following plants as forage species of H. alpinus: Salix (Salicaceae); Tussilago (Asteraceae); Thymus (Lamiaceae) and the following plants as forage species (of H. perkinsi): Senecio and Solidago (Asteraceae).
Pawlikowski & Kruszynski (1997) list Holosteum umbellatum (Caryophyllaceae); Taraxacum officinale (Asteraceae) and Potentilla arenaria (Rosaceae) as forage sources (of H. perkinsi) in Poland.
In Finland, the species is reported to visit Vaccinium vitis-idaea (Ericaceae)(Söderman & Leinonen, 2003)
In Oregon the species is essential to the production of marigold seed and is of considerable importance in the production of Zinnia (Asteraceae)(Roberts, 1972).