This chapter addresses some of the control problems involved in animal's visually guided 3D piloting. We formulated explicit control schemes which explain how insects may navigate without requiring any distance or speed measurements. The concept of the optic flow regulator, a feedback control system based on optic flow sensors, is presented. Based on a number of behavioral experiments conducted in our laboratory and elsewhere, we explain how OF regulators suffice to account for various insect flight patterns observed over the ground and over still water, under calm and windy conditions, and in straight or tapered corridors. These control schemes were tested in simulation and implemented onboard two types of insect-like robots, a micro-helicopter and a micro-hovercraft, which behaved very much like insects when placed in similar environments. These robots were all equipped with electro-optic OF sensors inspired by the results of our previous microelectrode studies on the motion sensitive neurons present in the flies' eyes. The simple and parsimonious control schemes described here do without any conventional avionic devices such as radio-altimeters, laser rangefinders, variometers, radars, sonars or GPS receivers. While these control schemes are little demanding in terms of neural resources-consistent with their integration in the less-than-one-milligram insect's brain-they show great potential for simplifying the design of aerial and space vehicles, with interesting prospects in weight-reduction and low consumption.