Abstract
Difference in flight time between male and female Platypus quercivorus that flew to a host tree was investigated in a forest of Quercus serrata and Q. crlspula damaged by the beetle. On cloudy mornings followed by sunshine, the female flight response peaked earlier than that of males. On clear mornings male and female flight reached a peak simultaneously, but females began and terminated flight earlier than males. We discussed that this difference is caused by a differential cost incurred by males and females before mating. Since cost for males may be to bore the entrance gallery, males fly in fine weather that make them actively after landing on the host. Since cost for females may be competition for a mate, females fly earlier irrespective weather in order to avert the competition.
