2020 UMN Cooperative Black Cutworm Trapping Network Report #1

Report #1 Week of March 30 - April 5, 2020

For more information: Black Cutworm Reporting Network

April 10, 2020


The 2020 black cutworm (BCW) trapping season has just completed its second week.  A single moth was captured in Meeker County.

The risk of crop loss due to BCW cut plants varies greatly from year to year. The missing pieces of the 2020 BCW puzzle is when, where, and how many moths will arrive from the south. That is where the trapping network comes in.  

Female BCW moths release a unique chemical compound (pheromone) to attract males. The BCW pheromone trap includes a small lure impregnated with a synthetic version of this pheromone. Unfortunate male moths, mistaking the odors wafting from the trap for an unmated female, fly into the trap where the trap’s sticky bottom captures them. Doesn’t seem very sporting, does it? Anyhow, only BCW moths react to the pheromone and then, only for the few days after migrants arrive and complete mating.  

This species-specificity and narrow capture window allows us to use these trap captures to locate when and where large flights of BCW migrate into Minnesota. This information helps us predict areas of Minnesota where corn, sugarbeets, soybean and other crops are at higher risk from damage, when crop injury will begin and just as importantly when cutting will stop. 

However, not all pheromones are as specific and useful as that of the BCW.  A few cooperators are running an additional trap for true armyworm, a pest of corn and cereal grains. 


At least three locations have sent photos of moths that are the same or similar to those in the photo sent by Joel Leafblad. 

These are not true armyworm moths or not likely even close relatives.  I am waiting for some specimens to try an ID.

BCW CooperatorsThe map to the left shows counties that have one or more BCW pheromone traps.  Spring weather is variable and, as a result, local areas will have higher or lower populations. Based in part on where low-level jet streams with sustained southerly flows are most likely to arrive, trapping is concentrated in the southern part of MN.

We have a very good network of volunteer trappers again this year checking traps daily and reporting their observations once a week from 67b traps in 41 counties. Thanks to the efforts of these volunteers, we should be able to do a respectable job of predicting BCW risk but field scouting is still important.  

During the spring, results of the 2020 trap network captures and predictions of BCW cutting will be posted weekly at: https://z.umn.edu/bcw-reporting. More information on black cutworm biology and damage are located at this site as well. There will be additional alerts for any BCW high-risk areas picked up by the network. 

This project is supported, in part, by the farm families of Minnesota and their corn check-off investment.

If you have not yet placed your traps, please do so as soon as possible. Also remember to report your captures to Travis (tvollmer@umn.edu) each Friday. We start analyzing the results Monday mornings. Because we are trying to determine where flight occurred, it is important to report both positive and negative captures each week. Finally, a quick email if a trap captures 8 or more moths over a 2-night period will be appreciated.

Until next week, 

Bruce Potter and Travis Vollmer