Frankliniella occidentalis (Pergande) and Frankliniella intonsa (Trybom) (Thysanoptera: Thripidae) are sympatric thrips species infesting crops including strawberry and pepper. Recently, F. intonsa was found as a dominant species locally even though F. occidentalis has been considered as a major species in Korea. We suggested interspecific competition as a underlying mechanism for the asymmetrical abundance. Effect of the competition on adult reproduction and longevity of the two thrips species was assessed in leaf cage and microtube arena, respectively. The number of reproduced progeny was reduced by 79% for F. occidentalis and only 43% for F. intonsa in competition condition. The mean longevity was also reduced greater in F. occidentalis (by 41%) than in F. intonsa (23%). Based on these results, it is probable that interference competition exists between the two species, and F. intonsa is better competitor than F. occidentalis. Therefore, interspecific competition might affect field occurrence pattern of the two thrips species.