Abstract
The active flight of the stink bug (ground bug), Aethus indicus, to an electric lamp was observed for several nights during July and August in 1975. The flight activity was in a unimodal type which commenced at after sunset and ended at midnight. The number of adults landed on the pan trap, which was 30co in diameter and placed just under the lamp, exceeded 100 per 5min in maximum. However, such an mass flight was suppressed by wind in over 3.3m per sec. We consider that their flight is activated by such a faint light intensity in the twilight. Dissection of the ovaries of the females, which were attracted to the light, showed the different degrees of maturation. These individuals were, it seemed, not stimulated with their particular reproductive requirement. On the other hand, we could observe that the adults rearing in the laboratory without food had a tendency to crawl out to the surface at sunset time. This phenomenon was extremely less when enough food was given. Therefore, it was expected that the flight activity was initiated for their food finding.
