Pinuspollen was found in pollen loads of 12 of 13 species ofOsmiabees and in the cell provisions of 6 of 7 species.Pinuspollen averaged 5.8% by volume in pollen loads of Pinus-carrying individuals and 3.0% in the cells of nests withPinuspollen. There was no difference in larval survival between cells with and withoutPinuspollen.Pinuspollen collection was fortuitous; bees became contaminated with pine pollen that was on their normal pollen and nectar hosts.