With their relatively simple nervous systems and purpose-designed behaviors and reflexes, insects are an excellent organism in which to investigate how visual information is acquired and processed to guide locomotion and navigation. Flies maintain a straight course and monitor their motion through the environment by sensing the patterns of optic flow induced in the eyes. Bees negotiate narrow gaps by balancing the speeds of the images in their two eyes, and they control flight speed by holding constant the average image velocity as seen with their two eyes. Bees achieve a smooth landing on a horizontal surface by holding the image velocity of the surface constant during approach, thus ensuring that flight speed is automatically close to zero at touchdown. Foraging bees estimate the distance that they have traveled to reach a food source by integrating the optic flow experienced en route; this integration gives them a visually driven "odometer." Insects have also evolved sophisticated visuomotor mechanisms for pursuing prey or mates and possibly for concealing their own motion while shadowing objects of interest.