2023 Iowa Moth Trapping Network Update: Week 5

May 9, 2023 3:13 PM
Blog Post

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.

TAW reports April 30 to May 6
Figure 1. True armyworm moth captures from April 30 to May 6. The bold number indicates the total moth count for the week (for counties with multiple sites, only the site with the highest total moth count is reported), while the smaller number in parentheses is a running total of the moth count for that trap location. Data is current as of May 9, 2023.

BCW reports April 30 to May 6
Figure 2. Black cutworm moth captures from April 30 to May 6. The bold number indicates the total moth count for the week (for counties with multiple sites, only the site with the highest total moth count is reported), while the smaller number in parentheses is a running total of the moth count for that trap location. Data is current as of May 9, 2023.

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:

Author: 

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 ...