It has been reported that the response to rotating objects by A. sieboldii S 6 indicates recognition of the objects as $ 9. The influences of colour, size and rotation velocity (RV) of discs on hovering ratio (HVR) were studied with experiments using a small electric rotating device. Among the rotating discs with white, yellow, orange, red, green, or blue alternating with black, the one with green elicited the highest HVR (98%), whereas the HVR to the yellow/black disc was lowest (32%). This suggests that yellow has a role as a warning coloration against predators rather than being involved in intraspecific recognition. – In the relationship of the HVR to RV of the grecn/black disc, the HVR reached a peak around 20-25 Hz. In relation of HVR to the size of the disc, the larger the diameter of the disc, the higher was the HVR, and when different sizes of discs were put side by side, A. sieboldii 3 3 had a tendency to respond to the larger disc of the pair.