Technical Abstract: The bacterial agent that causes Pierce’s disease of grapevine, Xylella fastidiosa, is the only known arthropod-transmitted prokaryotic plant pathogen that does not circulate in the vector’s hemolymph. Instead, bacteria are foregut-borne and semi-persistent, i.e. bacteria colonize cuticular surfaces of the anterior foregut, and are lost during molting, respectively. Exactly how a sharpshooter vector expels bacteria from foregut sites, while hypothesized, is still unknown. The present study used optical sectioning via confocal laser scanning microscopy to identify locations in undissected, anterior foreguts of the glassy-winged sharpshooter colonized by green fluorescent protein-expressing X. fastidiosa. Both spatial and temporal distribution of acquired X. fastidiosa was examined daily over acquisition access periods of 1 to 6 days, for both contaminated (field-collected) and clean (laboratory-reared) sharpshooters. Results provided the first direct, empirical evidence that established colonies of X. fastidiosa can disappear from vector foreguts over time. When combined with existing knowledge on behavior and functional anatomy of sharpshooter feeding, present results supported that the disappearance is caused by outward fluid flow (egestion) not inward flow (ingestion, i.e. swallowing). Thus, egestion is a critical part of the X. fastidiosa inoculation mechanism. Furthermore, a non-linear, spatiotemporal cycle of microbial acquisition into and expulsion from the foregut provided evidence for two types of egestion, i.e. rinsing and discharging. Comparison of acquisition results for field-collected vs. laboratory-reared sharpshooters suggested that there may be competitive binding for optimum acquisition sites in the foregut. Successful inoculation may depend, in large part, on bacterial load in the vector.