We investigated the mating and oviposition behaviors of the sorghum plant bug, Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae) under 25°C and 16L8D conditions in the laboratory in order to use the synthesized sex pheromone effectively as part of the integrated pest management. The ethogram of male courtship behavior was composed of the following four steps: approach, antennae, hold, and mounting. Both the durations from paring to copulation and copulation durations were almost same in light and dark conditions, suggesting that S. rubrovittatus males recognized the mate by using factors except visual stimuli in the short distance. The copulation rate of virgin females increased with an increase in days after adult eclosion. Females that copulated once received no additional copulations within three days after the first copulation. No significant differences in the preoviposition periods and total numbers of eggs deposited were observed between virgin and copulated females, which were paired with a male during their lifetime or until the first oviposition. On the other hand, virgin females had significantly longer longevities relative to copulated ones. Most of the eggs deposited by single copulated females were fertilized, suggesting that a single insemination provided enough sperm to fertilize all the eggs produced by S. rubrovittatus females during their lifetime.