Abstract
Activity rhythms of male and female adult Spodoptera litura F. were recorded by actograph. Time of female calling was observed in a laboratory and male responsiveness to sex pheromone in a dark period was estimated by the trap catch in a wind tunnel. Males showed activity just after light off which was followed by a less active period. Then they became active and were highly active in the latter half of an 8 hr dark period. Females were less active than males and small activity peaks were observed sporadically throughout the dark period. Many females showed calling around 1 hr after light off and thereafter calling activity was observed continuously till light on. Males remained responsive to a sex pheromone from 1 hr after light off to light on.Two peaks in the male attraction pattern in the field resulted from high male and female sexual activity just after light off and from high rate of male locomotion later in the dark period.
