By Dr. Fei Yang – Extension Corn Entomologist, University of Minnesota Department of Entomology, and Bruce Potter – Potter Brothers, LLC and University of Minnesota Extension retired
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| True armyworm moth. Photo: B.D. Potter |
The 2026 season has been relatively quiet for black cutworm and armyworm. Nevertheless, several significant immigration events for migrating black cutworm and true armyworm moths have entered Minnesota this spring.
Although arrivals have been lower than some years, larvae from both moth species should be considered when scouting in 2026. Black cutworm larvae derived from mid-April arriving moths are projected to reach 4th instar and be large enough to cut small corn. A couple of traps captured significant numbers of armyworm moths, so pay attention to fields with late-terminated cover crops, fields with grassy weeds, and areas of lodged grasses and small grains.
Additional information on 2026 (and the past year) moth arrivals as well as management information can be found at https://z.umn.edu/bcw-reporting including the following weekly reports.
March 17 – April 3 capture report and: 1st black cutworm moth capture. Conditions needed for crop threatening cutworm and armyworm populations. What do pheromone traps capture and measure. https://swroc.cfans.umn.edu/bcw-26-2
April 4-10 capture report and: Degree days and insect growth and development https://swroc.cfans.umn.edu/bcw-26-3
April 11 -17 capture report and: Black cutworm moths arrive in mass, Predicting outbreaks from migratory moths https://swroc.cfans.umn.edu/bcw-26-4
April 18-24 capture report and: How to scout more efficiently. Armyworm Alert https://swroc.cfans.umn.edu/bcw-26-5
April 25 - May1 capture report and: Finding economic problems. https://swroc.cfans.umn.edu/bcw-26-6
May 2- 8 capture report and: Economic thresholds. https://swroc.cfans.umn.edu/bcw-26-7
Although arrivals have been lower than some years, larvae from both moth species should be considered when scouting in 2026. Black cutworm larvae derived from mid-April arriving moths are projected to reach 4th instar and be large enough to cut small corn. A couple of traps captured significant numbers of armyworm moths, so pay attention to fields with late-terminated cover crops, fields with grassy weeds, and areas of lodged grasses and small grains.
Additional information on 2026 (and the past year) moth arrivals as well as management information can be found at https://z.umn.edu/bcw-reporting including the following weekly reports.
March 17 – April 3 capture report and: 1st black cutworm moth capture. Conditions needed for crop threatening cutworm and armyworm populations. What do pheromone traps capture and measure. https://swroc.cfans.umn.edu/bcw-26-2
April 4-10 capture report and: Degree days and insect growth and development https://swroc.cfans.umn.edu/bcw-26-3
April 11 -17 capture report and: Black cutworm moths arrive in mass, Predicting outbreaks from migratory moths https://swroc.cfans.umn.edu/bcw-26-4
April 18-24 capture report and: How to scout more efficiently. Armyworm Alert https://swroc.cfans.umn.edu/bcw-26-5
April 25 - May1 capture report and: Finding economic problems. https://swroc.cfans.umn.edu/bcw-26-6
May 2- 8 capture report and: Economic thresholds. https://swroc.cfans.umn.edu/bcw-26-7
Additional information can be found at https://z.umn.edu/bcw-reporting
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