Abstract: Variation in toxicity among formulations and species makes it difficult to extrapolate results to all species and all formulations of herbicides. We exposed larval wood frogs (Lithobates sylvaticus) from four populations to two glyphosate-based herbicides, Roundup Weed and Grass Control™ and Roundup WeatherMax™. 96 hour LC50 values for both formulations varied among the populations (RWGC: 0.