Scout early, and scout often, at least once every five days from mid-July until August.
Focus on the uppermost three or four leaves of the plant, searching for egg masses on the upper surface of the leaves or larvae on the tassels. Bright sunlight can help you spot shadows of egg masses through leaves.
Scout fields in pre-tassel stage first, as late-planted corn is less at-risk early in the season. After the late-tassel stage, WBC moths prefer to seek out dry beans or later planted corn fields.
Keeping track of WBC counts can help you know the pressure in your area and help you make informed spraying decisions.