Newly-emerged honey bees were placed in cages and fed sucrose syrup and one of the following single-pollen diets: Malus domestic Borkh., Brassica campestris L., Phacelia tanacetifolia L., Melilotus officinalis (L.) Pall., Helianthus annuus L., Pinus banksiana (Lamb.), artificial supplement or nothing.