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On the Move: Black Cutworm Moths Are Here

April 17, 2003

As reported in last week's Bulletin (issue no. 3, April 11, 2003), black cutworm moths are beginning to make themselves known in the southern counties. Let's recap the "intense" captures (nine or more moths captured over a 1- to 2-day period) from last week. Ron Hines, senior research specialist at the University of Illinois Dixon Springs Agricultural Center, reported in the "Hines Report"
that 19 black moths had been captured on April 7 in Pulaski County. In Gallatin County, Jeff Staley, Wabash Valley FS, reported an intense capture of moths over April 5-6 in two of his traps. On Monday, April 14, I received word from Mike Roegge, crop systems Extension educator in Quincy, of an intense capture in a trap operated by Sam Markert, Camp Point, April 11-12 and then again on April 13-14. Other captures of black cutworm moths, although not intense, have occurred in traps in Menard and McDonough counties, as reported by Matt Montgomery, crop systems Extension educator in Springfield, and Sean Evans, crop systems Extension educator in Macomb, respectively.

Reports of intense captures have been few and far between this season. The dates of cutting activity (fourth instars) can be predicted by accumulating degree-days from the date of the intense capture. The accumulation of 300 degree-days (base 50°), from the dates of intense captures, is projected to occur in Pulaski and Gallatin counties on May 4 and in Brown County on May 8. It is important to remember these projections are not exact and should be used as a guideline for monitoring black cutworm larvae. Projected dates of cutting are estimated by Bob Scott, Illinois State Water Survey, and will be provided in a table format in future issues.

Cutworm moths aren't the only organisms on the move: Growers are planting corn feverishly! As corn planting coincides with moth flights, it's going to be important to scout fields that are especially attractive for egg laying. Fields or areas of fields in which early season weeds were growing at the time moths flew into the area are at a higher risk than weed-free fields. If tillage or herbicides eliminate weeds 1 to 2 weeks before planting, any black cutworms that had been present probably starve to death. The presence of weeds only a few days before planting increases the likelihood of cutworm damage if larvae are present in the field. Begin watching emerging seedlings carefully for early signs of cutworm feeding (pinholes in the leaves) and for plants that have been cut off by larger larvae.

Table 1 from last week's Bulletin (issue no. 3, April 11, 2003) lists preventive control measures for black cutworms in Illinois. Updates of black cutworms will be included in future issues of the Bulletin. Again, please keep us informed of cutworm activity in your area. I am also looking for cooperators to send weekly counts from black cutworm traps to monitor the spread of the insect across the state. If you are interested in sending trap counts, feel free to e-mail me at, or call (217)333-6651.--Kelly Cook

Author: Kelly Cook

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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