The male mate-locating tactics are of the "searching” type in C. melanurum, and of the ”sit-and-wait” type in C. nipponicum. The male of C. melanurum actively makes searching flights for females during a limited period within a day and mates only during this period, while the male of C nipponicum mates during a longer period within a day. When it becomes cloudy, the reproductive activities of the male of C. melanurum sharply go down, whereas the reproductive activities of C. nipponicum are not affected so much as those of C. melanurum.