As a prerequisite to the elucidation of the sex pheromone of the green capsid bug Lygocoris pabulinus (L.), we studied the bug's reproductive development and behaviour. When kept under long-day conditions (L18:D6) at 25 °C, both males and females start to copulate 4 days after the final moult. Second matings occur in some females, even on consecutive days. The premating period is 10 min on average and copulation lasts 1 to 2 min. At long range, when males are attracted to traps baited with live females, we did not observe a specific calling position of the females. At short range, a characteristic courtship behaviour of the females was not observed either. Males showed a characteristic vibration of the abdomen, which was repeated several times before copulation. This behaviour can be used as a bioassay to test potential sex pheromone compounds.