Western flower thrips, Frankliniella occidentalis (Pergande), are major pests of the food and flower industry. Thrips hindguts are colonized by bacteria in the family Enterobacteriaceae. The relationship between thrips and their facultative symbionts is not well understood. While these bacteria have regularly been found in the hindgut of thrips, other possible colonization centers (i.e. midgut, foregut, ovaries) have not been determined. Furthermore, previous studies have indirectly shown that thrips bacteria do not infect the egg stage, as is the case with many coevolved insect-microbe systems, but coat an oviposited egg and are then ingested by larval thrips. It is not known if thrips bacteria invade adult female ovaries to access the eggs. To test if thrips bacteria penetrate female host ovaries and to determine colonization sites for thrips bacteria, we have developed in-situ hybridization methods to visually identify thrips bacteria in the various stages of insect development. Using antibodies and conjugates bound to a far-red fluorophore, we amplified the signal of thrips bacteria to overcome the autofluorescence common in thrips. Our technique allows us to monitor bacterial infection in thrips from egg to adulthood. This knowledge provides basic information about the interaction between this microbe and its pest host.