No. 1 Article 6/March 24, 2006

Catching Up on the Western Bean Cutworm

In 2004, the first western bean cutworms were found in Illinois. Traps were placed in 56 Illinois counties throughout northern and much of central Illinois and in some selected counties in southern Illinois. The goal of the trap network was to monitor for the presence and distribution of the western bean cutworm in Illinois. Operation of traps began on July 1 and continued through August 15. The traps were checked two to three times each week.

At least one moth was caught in 33 of the counties included in the trap network (Figure 3). Trap catches were higher in counties in northwestern Illinois, especially those along the Iowa border. Mercer and Whiteside counties reported the highest trap catch totals of 193 and 100, respectively. However, trap catches in Illinois pale in comparison to the number of moths caught in western and central Iowa. For example, in western Iowa, counties such as Woodbury, Pocahontas, and Guthrie all reported more than 1,000 western bean cutworm moths in traps placed in their respective counties. Monitoring results in their entirety can be found on the Iowa State Western Bean Cutworm Monitoring Web site.

These initial findings of the western bean cutworm trap network only signify that the insect is present in the state. If and when the western bean cutworm will become an economic pest is uncertain. However, we will continue to monitor in the coming year. In 2006, we plan to have at least two traps in every Illinois county. Surveys of cornfields will be done to positively identify larvae feeding in fields and to determine the extent of injury caused by the western bean cutworm.

As we get into the growing season, we will continue to provide more information on this insect, including its biology and how to monitor and scout for it. You can read more about the western bean cutworm from the Western Bean Cutworm Factsheet (Adobe PDF) and in other articles from the 2005 Bulletin: "Introducing the Western Bean Cutworm", "Western Bean Cutworm Adults Found in Northwestern Illinois Counties", and "Corn Earworm, European Corn Borer, Fall Armyworm, or Western Bean Cutworm: Which One Is Causing the Injury I'm Finding on My Corn Ears?".-- Kelly Cook

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