Visual-inertial integration enables bumblebees to land on rapidly moving flowers

Landing on a moving target is challenging for flying animals, particularly under dynamic outdoor conditions. For pollinators such as bumblebees, wind-induced flower motion adds substantial complexity to landing manoeuvres. Here, we investigate how bumblebees (Bombus terrestris) land on laterally oscillating flowers. Using high-speed stereoscopic videography, we quantified three-dimensional flight kinematics of 48 bumblebees approaching a sinusoidally moving flower-mimic and analysed their control strategies using system-identification and control-theoretic modelling. Landing dynamics were consistent with combined visual (optic-flow) and angular yaw-rate feedback, enabling precise sideways tracking and gaze stabilization. Sideways motion was captured by a proportional controller, whereas gaze control required a proportional-derivative structure. Both controllers yielded similar case-specific effective delays (approximately 54 and 52 ms). Surprisingly, optic-target-angle contributed negligibly to gaze control, indicating reliance on velocity-based rather than position-based cues. Lateral acceleration correlated strongly with body roll, consistent with the helicopter model of force redirection. These results reveal a modular visual-inertial control strategy enabling robust landings on moving targets and suggest principles for agile bio-inspired flight.