Gracilimiris litoralis Stonedahl and Henry is an infrequently collected mirine plant bug previously recorded from a total of 14 locales in Florida, Maryland, Mississippi, North Carolina, and Texas. It is newly reported from Alabama, Georgia, and South Carolina, with additional records given for Florida, Mississippi, and Texas. Although adults have been taken on cordgrasses, Spartina species, the bug's host-plant relationships have remained undocumented. During extensive sampling of spartinas and other grasses in the southern United States, I found nymphs of G. litoralis near the coast and inland only on three species of Spartina: sand cordgrass (S. bakeri), saltmeadow cordgrass (S. patens), and gulf cordgrass (S. spartinae). The mirid was not observed on two less architecturally complex species, big cordgrass (S. cynosuroides) and smooth cordgrass (S. alterniflora). Seasonal history of G. litoralis was followed from 2002 to 2010 (19 visits) by periodically sampling an inland colony of sand cordgrass near Avon Park (Highlands County) in the Lake Wales Ridge of the Florida peninsula. The presence of early instars in November, December, February, and March suggests that reproduction continues during winter. The presence of adults in all months of fieldwork (January–July; November, December), coupled with published records of adults from August to October, suggests that the bug is multivoltine.