In a social insect such as the honeybee, the survival of the colony depends on the success of its foragers. The bee optimizes its foraging success by returning to flowers of the species at which it has previously found food. This so-called flower constancy (see Chittka et al. 1999 for references) is based on the bee's capacity to learn and memorize specific flower signals (Menzel et al. 1993; Menzel & Müller 1996; Menzel 1999 and this volume) and to discriminate among different species by their different signals.

A bee returning to the feeding site in search of a flower, be it natural or artificial, must first detect the target from a distance. Once the flower has been detected, the bee will approach it up to a distance at which it is able to recognize whether or not the flower is similar to that stored in memory. Among the different sensory cues used, visual cues are of fundamental importance. In the rich market of coexisting and competing flower species, flower colors, shapes, and patterns are the visual cues that allow bees to recognize and discriminate profitable species.

Here we review studies concerned with the bee's use of visual signals for detecting and recognizing food sources. In the first part of the chapter, we examine the role of the bee's color vision in these tasks. In the second part, we look at the role of several spatial parameters contained in achromatic (black-and-white) stimuli.