We address some of the control problems involved in insects' and robots' visually guided piloting. We present explicit control schemes that explain how insects may navigate on the basis of optic flow (OF) cues, without requiring any distance and speed measurements. The concept of the optic flow regulator, a feedback control system based on OF sensors, is presented. We tested our control schemes in simulation, and implemented them onboard two types of aerial robots, a helicopter and a hovercraft. Our electronic OF sensors were inspired by the results of our microelectrode studies on motion sensitive neurons in the housefly's compound eye. The control schemes described do not involve any conventional avionic sensors like rangefinders or speed sensors, and show great potential for the autonomous control of air, underwater and space vehicles.