Contribution of Compound Eyes and Ocelli to Steering of Locusts in Flight Ii. Timing Changes in Flight Motor Units

Locusts (Orthoptera, Acrididae) were induced to fly while tethered within a simulated horizon display. Rotation of the horizon about the animal's long axis caused changes in the relative timing of the spikes of homologous flight muscles of either side. Changes in relative timing paralleled the pattern of head motions (Taylor, 1981) elicited by horizon rotation. Systematic changes in relative spike timing were also seen after the compound eyes were surgically disconnected and in response to forced head rotation. These results are discussed in relation to the functions of the compound eyes, the ocelli, and the cervical proprioceptive hairs for visual flight stabilization.