The southern chinch bug, Blissus insularis Barber, is the most damaging insect pest of St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze. However, there is little understanding of the impact of the insect feeding on the plant biomass or nutrient flux in tissues. The objective of this study was to measure biomass and nutrient change in St. Augustinegrass caused by feeding of southern chinch bugs. Chinch bugs were collected by vacuuming infestations in commercial and residential lawns in southern Florida. After collection, chinch bugs were placed in buckets containing St. Augustinegrass potted plants whereas controls were plants with no chinch bugs. Nutrient concentrations were measured for nine elements (N, P, K, Ca, Mg, Mn, Fe, Cu, Zn) in leaf and stolon tissue. At the termination of the test, chinch bug treated buckets had >100 chinch bugs/bucket in them and controls had none. Stolons were 31% shorter in chinch bug exposed plants than controls with no chinch bugs. Above-ground dry matter was reduced by 37% by chinch bug feeding. Plant leaf color was also significantly changed by chinch bug feeding from dark green to yellow. In general, chinch bug feeding decreased all nutrient concentrations, suggesting that the damage was broad in scale and reduced the plant's ability to maintain nutrients.