To evaluate temporal changes in grasshopper communities over a 5-y period (1997–2001), density and species relative abundance were estimated at 27 sites in Benito Juárez county, Southern Pampas, Argentina, established across vegetation associations with different disturbance histories. A total of 22 grasshopper species were collected, Melanoplinae being the most abundant and diverse subfamily, followed by Gomphocerinae, Acridinae, Copiocerinae and Leptysminae. Results allowed us to categorize years into nonoutbreak (1997, 1998, 1999), transitional (2000) and outbreak (2001) based on the spatiotemporal characteristics of grasshopper density trends. On average, grasshopper density was over 7 times greater in 2001 than in nonoutbreak years. During nonoutbreak years, grasshopper densities showed no significant variation across disturbance categories. During the outbreak year, densities were significantly higher in pastures and halophilous steppes, with highly disturbed pastures being the most affected sites of all. Species richness changed significantly in outbreak versus nonoutbreak years: nearly twice as many species were collected during the outbreak year. Although 22 species were collected, results showed that a small number influence overall abundance from nonoutbreak to outbreak conditions. Although Dichroplus elongatus, Covasacris albitarsis, and Scotussa lemniscata were the three topranked species throughoutthe studied period, D. elongatus contributed most to overall shifts in grasshopper density.