This is the first report of the 2025 season. Seven of 32 monitoring sites reported this week. European corn borer (ECB-E) was caught at one site, which also reported corn earworm (CEW). No other target moth species were detected.

The first spring flight of ECB-E typically begins when accumulated growing degree days (GDD), using a modified base of 50°F, reach 374. Current GDD accumulation averages around 353 across reporting sites—still slightly below the expected threshold for the first flight. Be sure to check degree day totals specific to your location.

If you have sweet corn in or approaching the tassel emergence stage during the first ECB generation, please see the “Managing ECB in plastic, row cover, or transplanted sweet corn” link to the right under “Pages” for management information.

J.W. Apple, Department of Entomology, University of Wisconsin-Madison

Table showing trap catch for 5.20.25 – 5.27.25.

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