1) The effect which the honey-guides of flowers have upon visiting bees is investigated with the use of large model flowers. 2) It is found that bumble-bees have a strong tendency to react to the edge of plain shapes, where there is a line of colour contrast with the background. If a contrasting honey-guide pattern is added, the bees still fly initially to the edge, but subsequently react often to the contrast margins formed by the pattern. On real flowers the honey-guide is arranged around the entrance to the nectaries and thus could direct the bees' reactions there. 3) The total patterns formed by honey-guides have no significance for bumble-bees. They follow converging lines to the flower's centre only because they always arrive first at the outer edge. 4) Bumble-bees do not distinguish between plain and honey-guided models when choosing from a distance, but having flown to a model, they hover longer over the latter. 5) Various observations on bees visiting real flowers are described and the validity of arguing from models to real flowers is discussed. It is believed that honey-guides will have qualitatively the same effect on both. 6) Some aspects of the effects of the honey-guides and the scent of flowers are discussed.