Grasshopper (Orthoptera: Acrididae) and Plant Relationships Under Different Grazing Intensities

Abstract

Grasshopper (Orthoptera: Acrididae) density and species composition were monitored in three southwestern Montana grazing areas. Periodic comparisons were made of percent cover, percent crude protein, percent water content, and total phenolics for grasses grazed by cattle versus grasses protected from grazing. Grasshopper densities and composition differed in three areas. Grazing reduced vegetative cover, accompanied by increases in ground litter and patches of bare ground. Plant nitrogen and water content decreased during the spring and then increased in late summer following rains. Phenolics levels were independent of grazing and weather fluctuations. Changes in grasshopper nymph densities roughly corresponded to springtime decreases of crude protein and water content in grasses. Nymphal mortality was inversely related to density. Grazing, weather, or changes in plant chemistry had little effect on grasshopper parameters of this study.