A Four-State Western Bean Cutworm Pheromone Trap Network to Track Moth Emergence and Improve Scouting

Richard Pope, Extension Program Specialist, Entomology (and Plant Pathology)


Western bean cutworm (WBC) is an insect pest of corn that emerged as an economic pest in west-central Iowa in the last decade. Since then, WBC has been observed in cornfields in central Iowa. WBC is difficult to manage, because moth flight (egg laying) and resultant larval emergence occurs in July when cornfields are difficult to scout. Additionally, WBC larvae enter ears where their feeding can cause severe damage to developing kernels. The window of opportunity for treatment is usually 7 to 10 days, starting with egg hatch and ending when the larvae enter the ears.  Some producers have reported up to 40% yield reductions, but damage can vary greatly from field to field.  


Three key issues need to be addressed concerning economically successful management of WBC in the upper Midwest, namely, knowledge of the local presence of populations of WBC, the factors that affect WBC infestation in corn, and the timing of moth emergence and subsequent oviposition and larval presence.  Pheromone traps are useful in monitoring emergence of WBC, and emergence patterns can be followed to focus scouting of fields. 


We recruited a network of volunteer agriculturalists to establish and monitor traps. These volunteers posted trap-capture data to www.ent.iastate.edu/trap/westernbeancutworm.  This website was made public and promoted through the ISU Integrated Crop Management newsletter, as a Partnership Perk (an expedited e-mail notice to the Iowa State University (ISU) Corn and Soybean Initiative partners), through a news release from ISU communications, and in live radio broadcasts. We cooperated with Pioneer Hybrids personnel and our ISU Field Crop Specialists for trap locations in Iowa and Missouri. Additionally, Kevin Steffey at the University of Illinois recruited cooperators that used our protocol and posted to the ISU Website, and the University of Minnesota posted data gathered from 6 light-trap locations in southern Minnesota. 

In total, there were 198 reporting traps placed in 116 counties in Iowa, Illinois, Missouri and Minnesota. The traps and counties covered by state were:

                        State                        Trap locations                        Counties
                        Iowa                        141                             79
                        Illinois                        43                             34
                        Missouri                      8                               7
                        Minnesota                  6                               6                                   


WBC known presence: From this year’s trap network, we expanded the known range of WBC east to Will County Illinois on the Indiana border, and south to Montgomery County Illinois, near Terra Haute, IN. Also, large regional populations were identified in Benton, Buchanan, Delaware, Jones, and Linn counties in Iowa that were not previously known.  

In late August we sent an e-mail survey to our trap cooperators asking them several questions about how they used the data, its value to them and what if any suggestions they have for future work with WBC. The following responses address both the dissemination of information to producers, and highlight some of the needs for future research on WBC.

Other comments volunteered by the survey respondents are listed here:


142 -- Integrated Crop and Pest Management

Page last updated: July 9, 2006
Page maintained by Linda Schultz, lschultz@iastate.edu