BCW 2026 Report 5

2026 University of Minnesota Cooperative Black Cutworm Trapping Network 

Report #5 April 18-April 24, 2026

This report was prepared April 28: 

Dr. Fei Yang - Extension Corn Entomologist, University of Minnesota Department of Entomology

Bruce Potter 

Greetings, 

Black Cutworm 

MN captures rpt5
Figure 1. Black cutworm moth captures April 18-24, 2026. Color shading represents the maximum two-night captures for trap(s) in the county. 

There were fewer black cutworm captures this week. The Meeker County trap captured 9 moths April 21-22 and was the only significant capture (Table 1, Figure 1). 

While not meeting an 8 moths / 2 night capture, the Dakota County trap was active April 20 to 24 with 6 moths captured April 23-24. 

I use the Midwestern Regional Climate Center to calculate current and projected degree days for both black cutworm and corn development. In addition to the tool for predicting 50o F based corn development degree days, this site has other weather and climate related information of use to agriculturalists. 

Hatching is projected to have started for some eggs laid from April 12-14 flights. Based on projected temperatures, black cutworm larvae will be large enough to start cutting corn as early as May 20 (Table 2).

Table county count report 5
Table projections report 5

 

How to scout for black cutworms and armyworms more efficiently. 
It usually works out better economically to find infestations when the larvae are small and before crop damage occurs.  However, both insects can be hard to scout for because the egg-laying habits of the moths, and subsequent habitat suitability for the larvae tend to be concentrated in particular fields, and even portions of fields.

How can we focus efforts on fields that are most likely to be infested by black cutworms? 

  1. Egg-laying females are attracted to untilled fields, particularly with soybean residue, to lay eggs.  Use tillage date and moth arrival dates (biofix) as a first step to prioritize fields for scouting. 

  2. Focus on fields with a history of winter annual weeds or early- emerging spring weeds that the egg-laying adults find attractive. Low-lying areas are often attractive. 

  3. Use degree-day projections to time your scouting before feeding by large larvae cause significant stand loss. Initial feeding by black cutworm larvae causes small holes in the leaves of weeds, corn and other crops. When the larvae reach the fourth stage, they can cut off small corn. Some stand density-sensitive broadleaf crops such as small, seedling sugarbeets can be cut by cutworms less than 4th instar. As the scouting season progresses, focus on corn that is 5-leaf stage or less.

  4. Corn Hybrids without above-ground Bt traits should be prioritized. Black cutworm larvae are controlled by Hybrids with the Vip3A or Cry1F proteins. To determine if the trait package in your hybrid controls black cutworm, download  The Handy Bt Trait Table for US Corn Production reference.


Armyworm alert
Armyworm data from Houston County missed last week’s report. This site captured 6 armyworm moths April 12-16.  On April 24, the Houston County trap captured 22 moths and continued to capture moths this week. 

Low (1-2 / night) moth captures also occurred in Dakota, Martin, Polk and Steele Counties April 21-24. 

Most of the armyworm moth captures have occurred in SE MN but that is also where we have the greatest trap density. Historically, pheromone trap captures of 20 or more moths tend to lead to economic infestations.  However, the infestations may not be limited to the area where the captures occurred. 

What about scouting armyworms?

  1. Two to three weeks after moths arrive, focus on your scouting efforts in fields and field borders with dense, vigorously growing grasses. Lodged field border and cereal crops, portions of fields with dense, grass weeds, and late-terminated grass cover crops are attractive to egg-laying female armyworms. 

  2. Scout when grass cover crops are terminated. This is especially true for corn planted into rye cover crops. 

  3. A sweep net is helpful in locating infestations of small larvae.

  4. Keep in mind, the potential for migration of “armies” of large larvae moving into crops when they deplete food sources.

  5. Only corn hybrids with the Vip3a trait will effectively control armyworm larvae.


For more information on migration, and other management facts of these two crop pests, see  corn-pest-management/black-cutworm-corn  and corn-pest-management/armyworm

This and previous reports can be found at  bcw-reporting 
This network is supported, in part, by the farm families of Minnesota and their corn check-off investment. 

Contact me with any questions and Happy trails, 

Bruce Potter
[email protected]
(507) 276-1184