By Adam Varenhorst and Philip Rozeboom et.al
Almost every year in South Dakota, there is a risk that grasshopper populations will reach levels capable of causing issues for rangeland, crops, as well as yards and gardens. Unfortunately, our prediction for the 2026 growing season won’t change the trend of the last few years. The first hard freeze in the fall of 2025 was late in many areas (Figure 1). Although I think most of us enjoy later cold weather in South Dakota, the later the first hard frost, the more time that adult grasshoppers have to remain active and lay eggs. This can result in increased grasshopper populations during the following year.
In addition to the later hard freeze dates, much of South Dakota is currently experiencing some level of drought (Figure 2).
Observations of grasshoppers tend to increase during drought conditions as the alternative food sources are not as abundant. This causes the grasshoppers to seek additional options including crops.
Annual Grasshopper Survey
The Animal and Plant Health Inspection Service (APHIS) of the USDA conducts an annual survey of grasshoppers in western South Dakota rangelands. The results from the 2025 survey indicate that there were very isolated areas that were at or above threshold (Figure 3). However, SDSU Extension numerous reports of grasshopper activity and severe crop cross in western South Dakota during 2025 that are not represented on the map. In addition, many reports were received in 2025 from areas in South-eastern South Dakota. Large populations of grasshoppers during the previous year are normally an indicator that grasshoppers will also be an issue during the following season. This is especially true when conditions increase the risk of grasshopper activity.
Scouting for grasshopper populations should begin shortly after planting in areas where grasshoppers were problematic in 2025 and continue throughout the growing season. Grasshoppers can reduce stand counts early in the season, cause extensive defoliation throughout the season, and prior to harvest damage the harvestable parts of the plants causing varying amounts of yield loss.
Some of the worst economic injury caused by grasshoppers in 2025 was due to grass being cut and bailed without consideration of the impact on neighboring crop fields. Prior to cutting an established pasture/field scout to determine grasshopper activity.
Source : sdstate.edu