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Issue No. 10, Article 4/May 27, 2005

Preparing to Monitor for Western Bean Cutworms

Until very recently, corn growers in Illinois have not had to be concerned about western bean cutworm, a cutworm species that attacks corn ears in midsummer. However, the distribution of western bean cutworms in Iowa has moved rather steadily eastward since 2000, encroaching on Illinois' western border in 2004. David Dorhout, a graduate student working with Marlin Rice (Iowa State University), placed a total of seven pheromone traps in Hancock, Henry, McDonough, and Warren counties in mid-July 2004 and captured five western bean cutworm moths in one trap in Warren County. This was a new state record for this species in Illinois.

Western bean cutworm adult (photo courtesy of Marlin Rice).

Because of the capture of western bean cutworm adults in Illinois in 2004, we are determined to learn more about the presence or absence of this species in Illinois in 2005, as well as its distribution if it has become "established." Working with Marlin Rice and others at Iowa State University, we will oversee a network of pheromone traps for western bean cutworms throughout most of northern Illinois and some of central and southern Illinois. University of Illinois Extension educators, Pioneer agronomists, and a few other ag industry personnel will cooperate to establish this network, with all data to be entered into a database that will include Illinois, Iowa, and Missouri locations. The traps will be set up by late June, and we'll keep you apprised of developments. Obviously, if we find western bean cutworm adults in pheromone traps, follow-up scouting in nearby cornfields will be necessary to determine whether the larvae pose a threat to corn production.

Pheromone trap for western bean cutworm adults (photo courtesy of Marlin Rice).

We'll write more articles about this insect pest closer to the time of its occurrence, covering scouting, economic damage and thresholds, and management options. In the meantime, we'll be planning for the appearance of western bean cutworms and letting you know what we find.--Kevin Steffey

Kevin Steffey

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