The last major outbreak was in the late 1970s and early 1980s. Some problems occur even in years of low numbers. Although they are most important on rangeland, they also attack field Crops, often with economic losses to the farmer. An exception is sorghum, which usually is not fed upon once it has reached about 10 inches in height. Grasshoppers lay eggs in undisturbed areas, usually in late summer and early fall.
Winged adults appear five to six weeks after hatch.
Eggs of a few Colorado species hatch in late summer and pass the winter as nymphs. Winged adults of these species usually appear early in the following summer, often causing undue alarm about unusually early grasshopper activity. Some of these early-season species are important on rangeland, but none are considered a threat to field Crops. Most field crop damage is caused by the differential, redlegged, two-striped and migratory grasshoppers, all species that follow the typical grasshopper life cycle. Crops is for early development to occur in weedy areas of roadsides, fence rows, irrigation ditches and other noncrop areas.