Measurements were made of corbicular areas (of a total of 1025 corbiculae) in 2 lines of honeybees (Apis mellifera) selected for high and low pollen hoarding respectively. The sample from each line comprised about 30 newly emerged workers from each of 9 queens representing 3 sublines. Analyses of variance revealed highly significant differences among the 18 queens (P « 0.0001) and between the lines (P « 0.0001). Mean corbicular area for the high pollen-hoarding line (1.909 ± 0.004 mm2) was greater than for the low hoarding line (1.874 ± 0.003 mm2), Of the 9 queens whose worker progeny had the largest corbiculae, 7 belonged to the high pollen-hoarding line. A Mann-Whitney U-test of rank indicated that the distribution of the queens for the 2 lines differed significantly (P < 0.05). Assuming the difference to be genetic, as indicated from a previous heritability estimate, unintentional selection for worker corbicular area must have been performed during selection for divergent pollen-hoarding ability in the colony.