Vision plays a key role in the detection of resources by diurnal pollinators. The anatomy of the eye, the nature of the photoreceptors and the neural connectivity of the visual system differ between insect pollinator groups. This suggests that each insect group could see the world in different shapes and colours, a result that could have important implications for the ecology and evolution of plant-pollinator networks. This is because the ability of pollinators to detect different flowers affects their relative efficiency at exploiting them and the profitability of visiting such flowers when there is competition for resources. Differences in visual systems could therefore trigger resource partitioning and allow flowers some control over their pollinators. Because the only insect pollinator for which the visual system has been studied in any depth is the honey bee, Apis mellifera, we propose to study the visual system of three different species: a solitary bee, Osmia cornuta, a hover fly, Episyrphus balteatus and a diurnal moth, Macroglossum stellatarum. We will determine the ability of these species to detect objects of different sizes against their background as a function of the contrast between background and object. We will also study how these species perceive colour differences. Based on these results, we will develop and test models exploring the extent to which differences in perceptual abilities of pollinators can lead to resource partitioning. This information is essential to determine under which conditions pollinators will be able to detect flowers of different sizes, shapes and colours, and hence to predict the extent to which flowers can advertise their reward to certain pollinators while remaining relatively inconspicuous to other pollinator groups.