by Regina Stacke (Researcher, Dept. of Entomology), Arthur Vieira Ribeiro (Researcher, Dept. of Entomology), and Robert Koch (Extension Entomologist)
Cutworms and soybean aphids were detected in soybean last week in Dakota County, Minnesota. We have also heard reports of cutworms in soybean from other locations in Minnesota and neighboring states.
Field scouting performed by our team on June 3, 2026, revealed soybean seedlings that had been cut. Digging around near the plants uncovered caterpillars that were collected and identified as dingy cutworm and variegated cutworm.
Cutworms can cause stand losses by cutting young soybean plants at or near the soil surface. The risk of cutworm infestations are often greater in fields with dense early-season vegetation, such as fields with significant weed growth or those planted under no-till practices.
Scouting for cutworms should be performed once or twice a week from plant emergence until plants are past the V5 stage. Inspect 20 consecutive plants in each of five representative areas of the field to calculate the percentage of plants that have been cut or girdled. For seedlings, treatment is recommended when 20 % or more of plants are cut, stand gaps exceed one foot, and cutworms are actively present. If control is warranted, apply the labeled rate of registered insecticides following the directions on the product label. For a better understanding of soybean stand loss and decision making, review "Soybean damage and replanting”.
a) Cutworm found near a cut soybean plant (photo credit: Regina Stacke). b) Dingy cutworm and c) variegated cutworm collected from the soybean field (photo credits: Arthur Ribeiro).
In addition, soybean aphids were found on plants in this same field in Dakota County. Early in the season like this, the presence of ants or lady beetles on plants can be an indicator of aphid infestations. While populations are currently low and far below any treatment thresholds, this update serves as a reminder that soon we’ll need to be scouting our fields for this pest.
Early in the season (around mid to late June), scouting can be focused on fields where aphids generally tend to show up first. Then, as the season progresses, you should start scouting all your fields more regularly. For a more detailed refresher, review “Scouting for soybean aphid”. The threshold to determine when to apply insecticides is 250 aphids per plant, with more than 80 % of plants infested and populations of aphids increasing.
Soybean aphids and ants on a soybean plant (photo credit: Regina Stacke).
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