Very few moths were reported by our cooperators last week. During week 5 of the Iowa Moth Trapping Network (April 30 to May 6), our cooperators reported 41 black cutworm (BCW) and 32 true armyworm (TAW) moths around the state, and there were no new significant flights of BCW to report. However, based on significant flights that occurred during April, we were able to predict initial cutting dates for BCW using accumulated and forecasted growing degree days. Predicted cutting dates can be used as a guideline to begin scouting for BCW. I expect cutting to occur earlier than usual in Iowa, because early-May temperatures have been warmer than usual and insect development tends to be quicker with higher temperatures.
Although we can’t predict TAW activity with a model like we can for BCW, it is important to scout for TAW once corn has emerged. Prioritize fields with a cover crop or other green vegetation (i.e., weeds) this spring. Green tissue is attractive to migrating moths for egg-laying. You can find more information about identification and scouting for TAW here.
Week 5 report
Most of the TAW and BCW moths seemed to arrive over the weekend (April 29-30), since most of the reports occurred on May 1. Figures 1 and 2 show the Week 5 trap reports for true armyworm and black cutworm, respectively.
Follow the links to see the report from Week 1, Week 2, Week 3, or Week 4. 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:
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- Extension Education Specialist, Entomology