Reports received: 30 of 34 monitoring sites submitted data this week.

Trap catches this week:

• European corn borer (ECB-E): reported at 6 sites
• European corn borer (ECB-Z): reported at 3 sites
• Corn earworm (CEW): reported at 19 sites, 15 high enough to be on a 4,5, or 6 day spray schedule
• Fall armyworm (FAW): reported at 4 sites
• Western bean cutworm (WBC): reported at 16 sites

It is recommended that all fields that are in the whorl or early tassel stage be scouted for WBC egg masses with a 4% threshold for processing sweet corn and a 1% threshold for fresh market sweet corn. WBC usually lay eggs on the upper side of the top 1-3 leaves of pre-tassel corn. After tasseling has finished WBC seek out younger corn or dry beans.

It takes between 5-7 days for eggs to hatch. It is critical that sprays are timed before the larvae have a chance to enter the ear. The egg mass will become purple in color approximately 24 hours before egg hatch (see photo).

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

Table showing trap catch for 7.8.25 – 7.15.25.

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