Orius strigicollis is a predatory bug that attacks small arthropods, such as thrips, and augmentative release of commercial strains has been widely conducted in greenhouses in Japan. The accurate evaluation of its effectiveness is essential for successful biological control programs. However, because Orius species occur naturally in the field, it is difficult to discriminate O. strigicollis from other Orius species. Furthermore, it is necessary to discriminate commercial strains of O. strigicollis from field populations. In this review, we introduce two types of molecular procedures: (1) a multiplex polymerase chain reaction technique to identify Japanese Orius species, and (2) microsatellite DNA markers that can be used to measure genetic diversity within populations of O. strigicollis and to discriminate field and commercial strains. The usefulness of molecular ecological approaches is also discussed.