The trapping season for black cutworm has come to an end. We appreciate our cooperators for tirelessly checking traps the last two months and reporting their captures so we can provide the most accurate scouting information for these pests. To recap, we had 15 volunteers participate from 18 counties in Iowa. A total of 22 black cutworm traps were placed and monitored during April and May. Because of these efforts, we were able to provide weekly updates of moth activity and predict cutting dates for Iowa. This blog contains the most recent estimates of cutting dates.
Trapping Update
Between May 25 and June 1, 14 trap sites reported a total of 20 black cutworm moths captured in traps (Figure 1). No new significant flights were reported during the last week.
2026 Season Totals
Although finding more total moths in an area does not necessarily mean you can expect more damage to occur, knowing where moths were captured can give an idea of where to expect activity. Figure 3 shows the total number of black cutworm moths reported in each county from April 1 to June 1. In total, our cooperators reported 576 moths across the state during the trapping season.
Plan to Scout!
Using historical temperature data from the Midwest Regional Climate Center database, Table 1 shows the current projected cutting dates in counties that have had a significant flight.
Some cutting date predictions have already passed, so it is crucial to scout fields as crops emerge, especially in areas with green plants at the time of planting that could harbor cutworms. Plan to scout well in advance of cutting dates that have not occurred yet.
| County (Crop Reporting District) | Significant Flight Date (Biofix) | Projected Cutting Date |
|---|---|---|
| Jackson (East Central) | April 12 | May 9 |
| Tama (Central) | April 12 | May 10 |
| Polk (Central) | April 13 | May 10 |
| Buena Vista (Northwest) | April 22 | May 23 |
| Cerro Gordo (North Central) | April 22 | May 22 |
| Franklin (North Central) | April 22 | May 22 |
| Marshall (Central) | April 24 | May 21 |
| Tama (Central) | April 24 | May 21 |
| Washington (Southeast) | April 26 | May 21 |
| Jackson (East Central) | April 28 | May 24 |
| Tama (Central) | May 17 | June 3 |
| Plymouth (Northwest) | May 17 | June 4 |
| Franklin (North Central) | May 18 | June 5 |
These dates may differ from what was reported in the ICM News article about predicted cutting dates for a few reasons: I update the blog weekly using actual temperature data, and cutting dates for regions without traps or significant flights are our best estimates based on available data. Note that black cutworm moths could continue to migrate to Iowa, so monitor corn until the V5 growth stage.
Caterpillars Found
Over the past week or so as corn has grown rapidly and folks are out checking stand, we have heard several reports of cutworm injury from all around the state. There seems to be a mix of black and dingy cutworms in some fields. Here are some resources to learn more about cutworms and other caterpillars that might be active now.
Black cutworm encyclopedia article
ICM Blog post about cutworms in forages
True armyworm encyclopedia article
Keep an eye out for any caterpillars, and watch for leaf feeding or cut, wilted, or dead plants. Many species are nocturnal and may be difficult to find during the day, but looking under residue or digging through the soil may reveal larvae.
More Information
You can find previous weekly reports on the ICM Blog.
Surrounding states also monitor and report black cutworm captures, as well as other moth species. If you live near the state border, it may be beneficial to check these resources periodically. More resources may be available than those listed here:
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 3, 2026. The information contained within may not be the most current and accurate depending on when it is accessed.
- Extension Specialist II