Twenty-nine of the 35 sites reporting this week. European corn borer (ECB)-E  was trapped at nine sites and ECB-Z was trapped at four sites. Corn earworm (CEW) was trapped at fifteen sites, with eleven sites high enough to be on a 4, 5 or 6 day spray schedule (see chart below). Fall armyworm (FAW) was caught at four sites and Western bean cutworm (WBC) was caught at eighteen sites this week.

Western bean cutworm numbers are beginning to go up this week with peak flight expected late July into early August. It is important to begin scouting for egg masses even if cumulative trap catches have not reached 50, as egg masses have been found when cumulative trap catch was still in the single digits. WBC will usually lay eggs on the upper side of the top 1-3 leaves of pre-tassel corn, close to the leaf base. After tasseling has finished WBC seek out younger corn or dry beans. To scout for egg masses check the top 3 leaves of ten corn plants in ten locations throughout the field. The eggs are easy to observe if you view the leaf while holding it towards the sun. The egg mass will appear as a distinct shadow (see photo).

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).

Table showing trap catch for 7.2.24 – 7.9.24.

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