Key Takeaways
WBC has been detected in Nebraska, making timely scouting important as moth flight continues through the summer.
Scouting should focus on egg masses and early larvae before they move into the ear, where control becomes more difficult.
Nebraska trapping networks and degree-day models can help growers and crop consultants track moth activity and guide management decisions.
Western bean cutworm (WBC) has been detected in several regions in Nebraska this year. This native pest can cause significant damage in Nebraska and throughout the Corn Belt.
Adult moths emerge every year from May through the summer, depositing eggs on the upper leaf surfaces of corn and dry bean plants. After hatching, larvae feed in stages, beginning in the whorl before moving to the ear. These infestations can cause yield loss, grain molds and other fungal problems in the field.
In corn, the primary management tools are the transgenic Bt Viptera trait and insecticides in non-Bt fields. Non-Bt corn should only be treated when populations exceed economic thresholds (Paula-Moraes et al., 2013), and scouting is a key aspect for detecting egg mass deposition and early larvae before ear colonization (Paula-Moraes et al., 2012). The critical stage for WBC is in the late whorl stage, when scouting should be prioritized.
The University of Nebraska–Lincoln offers several tools to help detect WBC moth activity in the state and to guide field scouting for egg masses and early larval infestations of this pest (Scouting for WBC egg mass).
A statewide pheromone trapping effort is underway in Nebraska to increase access to local pest-monitoring information for farmers, agronomists and crop consultants. Figure 1 shows the locations of traps maintained by extension educators and collaborators throughout the Corn Belt and Canada.
Information on WBC moth flight is available through the Great Lakes and Maritimes Pest Monitoring Network.
Overall, WBC trapping helps improve management decisions while reducing unnecessary preventive insecticide applications. To participate in this effort, contact your local extension educator or Silvana Paula-Moraes for more information.
In addition, moth flight predictions, using degree-day models, is available in UNL’s AgriTools mobile app for Apple or Android.
Moth flight is also monitored using blacklight traps and pheromone traps. Blacklight trap data are available online from four Nebraska locations: Haskell Ag Lab, South Central Agricultural Lab, Eastern Nebraska Research and Extension Center, and West Central Research and Extension Center.
