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Issue No. 9, Article 3/May 25, 2007

First Captures of European and Southwestern Corn Borer Moths (and a Comment About Western Bean Cutworms)

With his "trap line" in southern Illinois from Pulaski County to Fayette County still in operation, Ron Hines, FS seed agronomist for Growmark's southern region, usually is the first to report first flights of a number of economic insect pests in the state. He reported the first captures of European corn borer and southwestern corn borer moths during the week ending May 15 in Pulaski and St. Clair counties. The trap in Pulaski County captured the first European corn borer moths of the season on May 9. The season's first southwestern corn borer moths were captured on May 11 at the same trap location in Pulaski County. An additional southwestern corn borer moth capture occurred between May 12 and 15 at the St. Clair County trap site. The dates of first captures of corn borer moths can be used to trigger accumulation of degree-days to predict development of both species. With a base temperature of development of 50°F, first instars of European and southwestern corn borers occur when 212 and 190 degree-days, respectively, have accumulated. Pinhole injury caused by small instars might be apparent as early as 2 weeks after first moth captures.

And corn growers in northern Illinois should take note, too. Dave Feltes, University of Illinois Extension IPM educator in the Quad Cities, observed a European corn borer moth in a grassy area in Whiteside County on May 22. His observation was a happenstance, but notable anyway. He and some other educators will be operating water pan traps with European corn borer pheromones this season, so we should have a pretty good handle this year on the population dynamics of this always-worth-watching pest.

Several Extension educators also will be monitoring pheromone traps for western bean cutworms again this year. The traps will be in operation beginning the third week in June. We want to be able to report first captures as well as to determine peak captures, by which we can recommend timing of field scouting activities. Pioneer Hi-Bred International also will have a network of pheromone traps in place. Everyone involved in these formal networks of western bean cutworm pheromone traps will enter their data at the Web site managed by specialists at Iowa State University. We will provide updates on our findings in articles in the Bulletin, but you can check out the captures over a wide geography at the Iowa State University site. Stay tuned.--Kevin Steffey

Kevin Steffey

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