The moth trapping season for black cutworm (BCW) and true armyworm (TAW) has wrapped-up. As a recap in 2025, we had 18 black cutworm sites in 14 counties and 16 true armyworm sites in 13 counties across the state that were monitored from early to mid April through the end of May.
Week 7 Recap
During the final week (May 25 – May 31, 2025) of the moth trapping network, a total of 7 black cutworm (BCW) moths were reported, with no significant flights.
Figure 1 below shows where moth traps are established throughout Iowa and summarizes black cutworm moth trap captures by county for the last week.
For true armyworms, 23 moths were caught last week with our trapping network, as indicated in figure 2 below. This was an uptick from the previous week (Week 6), where no true armyworm moths captured.
Final Numbers
Although more total moths in an area does not necessarily mean you can expect more damage to occur, knowing where moths were captured provides an idea of where to expect activity.
Figure 3 shows the total number of BCW moths reported in each county from April to the end of May. Most counties had one trap site; however, Hamilton, Muscatine, Pottawatomie, and Washington had two trap sites, so the total count is averaged between the two sites for those counties. In total, 334 BCW moths were reported across the state during the 2025 moth trapping season.
Figure 4 shows the total number of TAW moths reported in each county from April to the end of May. Counties with two trap sites included Muscatine, Pottawattamie, and Washington counties. Like with the BCW, the total count is averaged for the counties with two sites. In total, 238 TAW moths were reported across the state during the 2025 trapping season.
Report Larvae
Continue to scout cornfields, weekly for BCW activity until corn is V5 for any prolonged arrival of BCW larvae to the area. There have been reports of cut plants in some cornfields across the state. While you are scouting, also keep an eye out for TAW activity.
If you see larvae or evidence of feeding by black cutworm or true armyworm, please email crops@iastate.edu and include species, larval size, and date observed. You can also tag us on X (formerly Twitter) (@erinwhodgson and @ISUCropNews). This helps us refine our predictions in the future.
Past reports and other information
Follow the links to see the reports from Week 1, Week 2, Week 3, Week 4, Week 5, and Week 6 for 2025. 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 black cutworm and true armyworm 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:
A special thanks for all those that helped with the 2025 moth trapping network!
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on June 2, 2025. The information contained within may not be the most current and accurate depending on when it is accessed.
- Field Agronomist in EC/SE Iowa