The behaviour mediated by chemical communication of laboratory-reared Euschistus heros Fabricius was studied in cultures initiated with egg masses supplied from EMBRAPA in the Southern region in Brazil. The courtship behaviour of E. heros is described and this behaviour can be divided into two phases: long-range mate location and short-range courtship. The first comprises a sequence of movements, such as intense antennation and movement of wings, which leads the female to the vicinity of males. The second includes the interaction of both sexes once they are in close proximity. The first mating is observed in male insects between 12 to 15 days old and in female e. heros from between 10 to 14 days old. Both the quantitative and qualitative analysis of the data strongly suggest that male insects produce a sex pheromone that elicits attraction and mating behaviour in this species. For E. heros, the chances of attraction and mating are greater for males and females during the photophase and are greater if the females are attracted towards males. When the odour of live males was replaced by chemical extracts obtained by aeration collection from female insects, females were much more attracted to the test chamber of a dual-choice olfactomter. This finding also suggested that males release the pheromone blend that elicits sexual behaviour in females E. heros. Pentatomids are known to produce and release a defensive secretion when distributed. It is believed that the defensive secretions in adult insects are produced in metathoracic glands, which occupy a ventral position in the hind part of the metathorax, and are stored in the reservoir. Secretions are ejected when the insects are disturbed by, for example, a predator, eliciting an alarm behaviour. Both male and female E. heros release such a defensive secretion, however, the female defensive secretion is more concentrated than that of the male.