Traditionally, western bean cutworms have been a pest of field corn in Colorado and Nebraska. However, this insect pest has caused significant damage to some Iowa corn fields since 2000.
To assist in scouting efforts for this pest, a network of pheromone traps was established in Iowa starting in 2003. Each year these traps have detected the current distribution of the western bean cutworm and have provided information on the proper timing to scout for this pest. In 2004, western bean cutworm adult moths were captured in more than 90 pheromone traps placed throughout Iowa. The northernmost adult moth catches included the counties of Winnebago, Worth, Mitchell, Winneshiek, and Allamakee. The easternmost adult moth catches included the counties of Clinton and Scott.
To better understand the expanding distribution of the western bean cutworm, the pheromone trapping program has also expanded. This growing season the most extensive network of traps will be placed throughout Iowa, Illinois, and northern Missouri. Iowa State University Extension is cooperating with Pioneer
Hi-Bred agronomists and researchers at University of Illinois at Urbana-Champaign to conduct this extensive trapping program.
What are western bean cutworm pheromone traps?
Pheromone traps consist of a one-gallon plastic milk jug. Square windows (4-inches in length) are cut in the sides of the jug (see photos). A 2-inch space between the window and the bottom of the jug serves as a reservoir that is filled with a 4:1 mixture of water and antifreeze, and a few drops of dish soap. A paper clip, placed inside the jug cap, holds the pheromone lure in place.
What does a trap cooperator do?
All pheromone traps will be started on July 1. Each day, trap cooperators will strain the moths out of the solution and will count the adult western bean cutworm moths. They will then enter the results on a Web site that is accessible to the public.
These traps will reflect the moth flight within an area and will indicate the proper time to start scouting for western bean cutworm eggs. In the next few weeks, we will provide more information on accessing the Web site to determine moth flight in your area, scouting protocols, treatment thresholds, and management options for this pest.
This article originally appeared on page 127 of the IC-494(15) -- June 20, 2005 issue.