Gut symbionts play crucial roles in host development by producing nutrients and defending against pathogens. Phloem-feeding insects in particular lack essential nutrients in their diets, and thus, gut symbionts are required for their development. Gram-negativePantoeaspp. are known to be symbiotic to the western flower thrips (Frankliniella occidentalis). However, their bacterial characteristics have not been thoroughly investigated. In this study, we isolated three different bacteria (BFoK1, BFiK1, and BTtK1) fromF. occidentalis,F. intonsa, andT. tabaci. The bacterial isolates of all three species containedPantoeaspp. Their 16S rRNA sequences indicated that BFoK1 and BTtK1 were similar toP. agglomerans, while BFiK1 was similar toP. dispersa. These predictions were supported by the biochemical characteristics assessed by fatty acid composition and organic carbon utilization. In the bacterial morphological analysis, BFoK1 and BTtK1 were distinct from BFiK1. All these bacteria were relatively resistant to tetracycline compared to ampicillin and kanamycin, in which BFoK1 and BTtK1 were different from BFiK1. Feeding ampicillin (100,000 ppm) reduced the bacterial density in thrips and retarded the development ofF. occidentalis. The addition of BFoK1 bacteria, however, rescued the retarded development. These findings indicate thatPantoeabacteria are symbionts to different species of thrips.