The structure of the visual system of the tiger beetle larva has already been reported (Toh & Mizutani, 1994a, 1994b; Toh & Okamura, 2001), but it is presented again to understand the present work. The tiger beetle larva possesses six stemmata on either side of the head (Fig. 3). Theyare numbered 1–6 after Friederichs (1931). Of the six, two pairs of large stemmata (1 and 2 in Fig. 3) seemed to be concerned with range estimation (Toh & Okamura, 2001). Since stemma 1 was the largest of the six, it was exclusively examined in the present study. It is referred to here as the (posterior) large stemmata or eye.