The standard economic threshold for soybean aphid recommended throughout most of the Midwest is 250 aphids/plant on 80% of plants. This threshold is based on experiments conducted over a 3-year period in Iowa, Michigan, Minnesota, Nebraska, North Dakota, and Wisconsin. In 2006, we performed experiments in three South Dakota locations, testing a range of different soybean aphid thresholds under field conditions. There was no yield loss when we employed a threshold of 250 aphids/plant, compared to lower thresholds of 0, 10, and 100 aphids/plant. These results validate the use of the Midwest Standard Threshold for soybean aphid in South Dakota (250/plant), and the State is adopting this new economic threshold.