Reports received: 22 of 34 monitoring sites submitted data this week.

Trap catches this week:

• European corn borer (ECB-E): reported at 4 sites
• European corn borer (ECB-Z): reported at 6 sites
• Corn earworm (CEW): reported at 10 sites
• Fall armyworm (FAW): reported at 2 sites
• Western bean cutworm (WBC): reported at 2 sites

Sweet corn fields are currently in tassel emergence and silking stages. Scouting thresholds differ based on crop stage:

• Tassel Emergence:
  • Threshold: 15% of plants infested
  • Note: As tassels begin to emerge, larvae will move downward to seek sheltered feeding sites. Timing insecticide applications before larvae bore into protected plant areas is critical for effective control.
• Silking Stage:
  • Threshold: 5% of plants infested
  • Scouting Tips: Focus on the ear zone—two leaves above and one leaf below the ear—checking for egg masses, feeding damage, and live larvae.

Many sites reported CEW catches this week. While CEW is difficult to detect through field scouting alone, pheromone trap catches can help guide spray timing, especially in silking corn. Refer to the spray interval table at the bottom of this post. If the daily high temperature has stayed below 80°F for the past 2–3 days, add one day to the recommended spray interval.

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

Table showing trap catch for 6.17.25 – 6.24.25.

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