Fig. 1. (A) The flight arena. During the experiments, the bumblebee was fixed inside this arena, and was given a visual stimulus in the vertical direction. (B) Magnified view of one wall of the arena. The inside wall contains 16 rows of LEDs in the horizontal direction, and 32 in the vertical direction. The diameter of each LED is 5.5 mm. We displayed horizontal stripe patterns by lighting alternate 8 rows of LEDs, that is, the period of the stripes was 88 mm. Those stripes were visually oscillated in the vertical direction by using a computer control. The oscillation amplitude was kept constant at 33 mm (6 dots of the LEDs), whereas the oscillation frequency was varied at 0.9, 1.8, 3.6 and 7.4 Hz (i.e. 5.6, 11, 22 and 46 rad s^-1).