The sorghum plant bug, Stenotus rubrovittatus (order Heteroptera: family Miridae), is a notorious insect pest in Japan that causes pecky rice. In the present study, we sampled this insect pest in the northern part of Honshu Island in Japan and investigated its associated microbiota. The results obtained showed that Pantoea dominated the associated microbiota and was the sole genus detected in all samples. The dominant Pantoea were phylogenetically close to rice pathogens. The present results suggest that the sorghum plant bug needs to be regarded and controlled not only as a notorious insect pest, but also as a potential vector of rice pathogenic Pantoea spp.