Japanese nine-spotted moth Amata fortunei and related species A. germana were diurnal moths and sympatric. We observed that A. fortunei males flow in the early morning, while A. germana males did in the late afternoon. Adults have different body colorations: A. fortunei have two yellow bands on the 1st and 5th segments of their abdomens (two–band type); A. germana have yellow bands on each segment (each–band type). To evaluate the importance of visual cues in mating behavior, we conducted the experiments with crude extract and an additional model stimulant. A. fortunei males responded more to model females with the same number and a similar area of yellow bands to the original conspecific females than to those with more bands and a greater total band area, suggesting that a dissimilarity in band number and area to conspecific females could interrupt male mating behavior. On the other hand, A. germana males responded to females A. fortunei as same as conspecific females, suggesting that importance of visual cues in mating behavior of A. germana could less than that of A. fortunei. In conclusion, two species have different time schedules for mating and different sex pheromone components are involved. These suggest that both differences in pheromone components and body coloration played a role in speciation within the genus Amata.