I experimentally examined in Bidens aristosa whether extent of flower symmetry affected pollination by insects. Flowers that were treated to increase asymmetry were visited by significantly fewer pollinators than control flowers. Flowers that remained symmetrical after manipulation showed no change in pollinators relative to the controls. These results suggest that insect pollinators have a preference for symmetrical flowers, and that radially symmetric flowers are better at attracting pollinators than their asymmetric counterparts.