In field cage experiments, 17 native and introduced grasses and a native sedge, grown in pure culture, differed in their effect on the growth, survival and rate of population increase of the clear-winged grasshopper, Camnula pellucida. In terms of eggs deposited, Festuca rubra permitted a 24-lold population increase in a 1-year test; in tests repeated in 2 consecutive years, Agropyron elongatum, A. cristatum, Elymus junceus, Poa pratensis and P. compressa produced average annual increases of 10- to 18-fold; A. intermedium, A. dasystachyum, A. trachycaulum var. typicum, A. riparium, Poa ampla, and Bromus inermis, 3- to 8-fold. Agropyron smithii, Elymus canadensis, Stipa spartea, S. viridula, Bouteloua gracilis and Carex stenophylla var. enervis (1 year’s results), 2-fold or less. Percentage survival to the adult stage, rate of development, and apparently, robustness, were all positively correlated with population increase, but not strongly.