Recently a colony of Solenopsis invicta, the red imported fire ant (RIFA), was intercepted on Gamman pier, Pusan port in Korea by Animal and Plant Quarantine Agency. It has been generally known that RIFA has two social forms as monogyne and polygyne, which showing the behavioral differences between the two forms and dictated by a pheromone binding protein, Gp-9. The social forms of the RIFA colony was revealed as polygyne form, when the GP-9 gene was analyzed by three allelic discrimination assays including Real-Time PCR (RT-PCR), rh-Amp SNP Genotyping, and peptide nucleic acid probe-based RT-PCR in this study.