Since its description from North America (America boreali) in 1850, Hyperaspidius venustulus (Mulsant) has been recorded only from an adult at a locale in Georgia and from Miami–Dade County, Florida (number of adults unspecified). Its habits and habitats have remained unknown. This scymnine coccinellid is newly reported from South Carolina on the basis of 43 adults from grasses, mainly big cordgrass (Spartina cynosuroides (L.) Roth; Poaceae), in or near brackish marshes and along tidal waterways. Its probable prey on big cordgrass is the mealybug Dysmicoccus dennoi Kosztarab. Near stands of S. cynosuroides, the coccinellid was collected occasionally from marshhay cordgrass (S. patens (Ait.) Muhl.) and from a beardgrass, Andropogon tenuispatheus (Nash) Nash (sensu Weakley 2007), that was infested by the mealybug Trionymus clandestinus McConnell and the eriococcid or felt scale Eriococcus dubius Cockerell. A diagnosis of H. venustulus and color photograph of the adult habitus are provided to facilitate recognition of this little-known lady beetle.