Last week, moth flights into Iowa were slightly lower than previous weeks. In total, our cooperators captured 55 true armyworm (TAW) moths and 102 black cutworm (BCW) moths during Week 7 (May 8 to May 14).
Week 7 report:
Moths of each species were captured almost every day last week, and reports were relatively consistent throughout the week. No additional significant flights of BCW occurred during Week 7, but we predicted cutting dates based on previous significant flights, degree day accumulation, and historical weather data. Figures 1 and 2 show the Week 7 trap reports for true armyworm and black cutworm, respectively.
Follow the links to see reports from Week 1, Week 2, Week 3, Week 4, Week 5, and Week 6. You can also track moth flights, black cutworm significant flights, and projected cutting dates for Iowa, Illinois, and Wisconsin on https://corn.ipmpipe.org/insects/.
Surrounding states also monitor and report BCW and TAW captures. If you live near the state border, it may be beneficial to check these resources periodically. More resources may be available than what is listed here:
- University of Minnesota
- University of Missouri
- University of Illinois
- University of Nebraska-Lincoln
What is a significant flight? A significant flight of BCW occurs when 8 or more moths are captured over a two-night period; this serves as the “biofix” for degree-day accumulation and indicates an increased risk of black cutworm injury in corn. A degree-day model for black cutworm development predicts that larvae are large enough (4th instar or larger) to cut corn plants once 300 degree days (base 50°F) have accumulated since a significant flight occurred. Cutting dates have been predicted for Iowa: https://crops.extension.iastate.edu/cropnews/2022/05/begin-scouting-black-cutworm-corn.