After the reduction in the use of broad-spectrum insecticides, Adelphocoris suturalis (Hemiptera: Miridae) has become an important pest of transgenic cotton, Gossypium hirsutum L., in China. A. suturalis is a highly mobile insect, moving rapidly in and out of crop fields, and traps baited with sex pheromones may be useful in monitoring and controlling its numbers. However, little is currently known regarding the chemical communication based on sex pheromones by this species. To use the synthesized sex pheromone effectively as part of the integrated pest management, some fundamental biological parameters under which the pheromone is produced must be understood. In this study, attractiveness of adult females or males of A. suturalis to conspecific individuals was examined by Y-tube bioassay; we also investigated the female sexually mature age and circadian rhythm of male attraction to females of A. suturalis in the field in 2008 and 2010. Y-tube bioassay results indicated that only males were attracted to odors from sexually mature virgin females. Two-year field trapping experiments showed that 4–18-d-old virgin females effectively attracted males, and males were attracted to virgin females during the scotophase, with a peak between 1900 and 2300 hours. These results improve our understanding of the sexual communication behavior of A. suturalis and provide evidence of female-produced sex pheromone in this species.