SEPARATION OF TRANSLATION AND ROTATION BY MEANS OF EYE-REGION SPECIALIZATION IN FLYING GYPSY MOTHS (LEPIDOPTERA, LYMANTRIIDAE)

A partial functional specialization of eye regions in the visual control of flight was studied in male gypsy moths, Lymantria dispar, under open-loop conditions. When stimulated by means of a rotating striped drum, surrounding either the moth's longitudinal or its transverse body axis, the induced torque response was always such as to compensate for a simulated translatory disturbance of flight, if the stimulus was restricted to the ventral visual field. If restricted to the lateral visual field(s), the response was always such as to compensate for a simulated rotatory disturbance. Though the conclusions refer to only a limited subset of visual stimuli the moths experience during free flight, the induced responses give reason to suppose that at least some of the simultaneous control of translation and rotation in free flight is based on a regional specialization of the compound eye.