Week 6 (May 7 to May 13) of the Iowa Moth Trapping Network was vastly different than the week before. Our cooperators reported 239 black cutworm (BCW) and 295 true armyworm (TAW) moths, with several significant flights occurring around the state.
Recall that we predicted initial cutting dates for black cutworm earlier this month. Predicted cutting dates should be used as a guideline to begin scouting for black cutworm. The predicted initial cutting dates have come and gone for much of the state, but these additional significant flights could mean prolonged feeding by black cutworm in some cornfields. I have updated the predicted cutting dates for black cutworm on the Corn ipmPIPE website. Continue to scout corn until it reaches V5 – at this stage, corn is no longer susceptible to cutting by black cutworm.
Continue to scout fields for true armyworm as well. For both pests, prioritize fields with a cover crop or other green vegetation (i.e., weeds) this spring. If corn or soybean was planted into a living cover crop or if the cover crop was not terminated at least 2 weeks prior to planting, those fields may be at higher risk for true armyworm or black cutworm feeding since moths look for green vegetation to lay eggs on once they arrive here. You can find more information about identification and scouting for true armyworm here.
Week 6 report:
Most of the moths arrived during the first half of the week (May 7 to May 9), but moths of both species were reported every day during Week 6. Below is a list of the significant flights that were reported last week:
- Hancock County (NC IA) – May 8
- Taylor County (SW IA) – May 8
- Floyd County (NC IA) – May 9
- Hamilton County (C IA) – May 9
- O’Brien County (NW IA) – May 9
- Story County (C IA) – May 9
- Washington County (SE IA) – May 9 (potentially significant)
- Keokuk County (SE IA) – May 10
- Buena Vista County (NW IA) – May 12
- Sac County (WC IA) – May 12
Figures 1 and 2 show the Week 6 trap reports for true armyworm and black cutworm, respectively.
Follow the links to see the report from Week 1, Week 2, Week 3, Week 4, or Week 5. You can also track moth flights and black cutworm significant flights for Iowa, Illinois, and Wisconsin at 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
Ashley Dean Agriculture and Natural Resources Extension Specialist II
Ashley is an education extension specialist for field crop entomology at Iowa State University. She coordinates the Iowa Moth Trapping Network, the Regional Corn Rootworm Monitoring Network, and the Iowa Pest Alert Network. She also develops educational resources for field crop pests in Iowa and ...