Research on the visual behavior of insects has uncovered a number of cues that are used for controlling and stabilizing flight and for extracting information about the structure of the environment. Flies monitor their egomotion and maintain a straight course by sensing the patterns of image motion that are induced in the eyes. Bees flying through a tunnel maintain equidistance to the flanking walls by balancing the speeds of the images of the two walls. This enables them to safely negotiate narrow passages or to fly between obstacles. The speed of flight in the tunnel is controlled by holding constant the average image velocity as seen by the 2 eyes. This ensures that the bee slows down to a safer speed when the passage narrows. Bees landing on a horizontal surface hold constant the image velocity of the surface as they approach it, thus automatically ensuring that flight speed is close to 0 at touchdown. Flies and bees distinguish objects from backgrounds by sensing the relative motion between the images of the object and the background. Ranges of objects are gauged in terms of the speeds of motion of the images of the objects. Foraging bees estimate the distance that they have traveled to reach a food source by integrating the optic flow experienced en route—they possess a visually driven odometer.