Projected Cutting Dates for Black Cutworms: Don’t Forget to Scout

Kelly Estes, Illinois Agricultural Pest Survey Coordinator, works with a network of volunteers across the state to monitor flights of key insect pests, including the black cutworm. Significant flights (nine or more moths trapped over 2-day period) of black cutworm moths occurred in Ford County (April 30), Mercer County (May 2), Lee County (May 4), Whiteside County (May 5), and Henry (May 10). By using these dates as a biofix and projecting heat unit accumulations we estimate that cutting of corn seedlings could begin to occur in fields on the following dates: Ford County (May 24), Mercer County (May 25), Lee County (May 31), Whiteside County (June 1), and Henry (June 3). Rather than wait until cutting begins to take place, producers are encouraged to look for early signs of leaf feeding as a potential indicator of cutting that may ensue. As stated in a previous Bulletin article, don’t assume that all Bt hybrids offer the same level of cutworm protection. Plants in the 1- to 4-leaf stage are most susceptible to cutting. Cutting of plants earlier than these projected cutting dates is possible — localized intense flights may have occurred and were not picked up by our volunteers. For more information on the biology, life cycle, and scouting procedures I encourage you to review our Department of Crop Sciences black cutworm fact sheet.

Mike Gray, Professor and Extension Entomologist