Plant tolerance to herbivory is an important component of plant competitive ability, which can facilitate the plant invasion process. The prediction of higher tolerance to herbivory in invasive plants has received mixed support in experimental studies, partially because of differences in methods of estimating plant tolerance in terms of plant growth. Using nondestructive methods to accurately estimate aboveground biomass, a standard measure of plant growth, can be challenging, especially for grasses. In addition, using different proxies for plant biomass may potentially cause mixed results in the estimation of plant tolerance. To address these issues, in our study, we conducted field and greenhouse experiments using native Andropogon gerardii Vitman and Bouteloua curtipendula (Michx.) Torr. and exotic Bothriochloa ischaemum (L.) Keng and Miscanthus sinensis Andersson grasses and examined their relative response to nymphal Melanoplus spp. grasshoppers. We first determined that, in most grass species, the product (Plant height × Number of leaves) was the best predictor of changes in plant biomass during 3 wk of plant growth. Based on this best predictor in grasshopper herbivory assays, we then found no difference in tolerance to herbivory among our study grasses. These results suggest that exotic grasses, which have not yet become invasive at the study sites might not demonstrate strong allocation from defenses to growth and reproduction, at least at the current time in these locations.