The glassy winged sharpshooter (GWSS), Homalodisca coagulate, is a major agricultural pest that has caused millions of dollars in damages to the vineyard industry of California as well as been a significant agricultural nuisance in Texas. These insects have specialized organs known as bacteriomes, which contain bacteriocytes, insect cells that house bacterial endosymbionts. Studies have indicated that there exists a direct requirement of the bacterial endosymbionts for host survival. Molecular methods have shown that two bacteria are present as co-primary endosymbionts, the gamma-proteobactiera, Candidatus Baumannia cicadellinicola, and the Chlamydia, Candidatus Sulcia muelleri. In our studies, we have utilized fluorescently labeled rDNA probes in conjunction with fluorescent in situ hybridization (FISH), and laser scanning confocal microscopy to localize these bacterial endosymbionts in situ in the bacteriomes. These data support previously published results showing that the Sulcia bacteria were pleomorphic in shape and cell wall deficient while the Baumannia were rod shaped and have a typical gram negative morphology. Currently, we are using a combination of digoxigenin labeled 16S rDNA probes, in situ hybridization, immunocytochemsitry, and transmission electron microscopy (TEM) to correlate species identification with ultrastructural morphology.