(a) Drosophila tethered at the tip of their thorax to a fixed tungsten pin, with their heads not glued and free to move, generated spontaneous saccades while viewing a uniformly lit screen. We tracked head angles relative to the long axis of the body and wingbeat angles, as indicated, with analysis of videos captured at 100 frames / s. (b) Sample traces of L–R WBA and head angles show a strong correlation between wing and head movements. (c) We computed the cross-correlation function between head angle and L-R WBA signal, for each flight bout > 6 s separately, and averaged this signal for a given fly. Each line represents the average cross-correlation function from a single fly (n = 5 flies). (d) We culled saccades from the L–R WBA trace as described (Methods) and plotted the head angles associated with each saccade. Gray lines represent averages from individual flies. Black and red traces represent averages across flies. Insets show the same traces at higher temporal resolution.