During their patrolling flight 6 A. sieboldii responded to a rotating fan by hovering. The dragonflies did not respond to the playback sound of the fan. However, they did respond to the rotation of a mini desk fan which was observed through the window of a sound insulated box. The dragonflies responded to rotation of discs of various patterns, even when the ambient temperatures were low for summer; thus they did not respond due to thermoregulation. Only 6 <5 responded, and they did not respond to rotation of low velocity. — <J <J responded to a suspended S or 9 that was fluttering, but not when it was still. Therefore, it was concluded that the response to rotating objects by <5 <J might be regarded as behaviour to ascertain whether a rotating object is a 9 or not. The hovering rate (HVR) in relation to rotation velocity and colour patterns is discussed.