"Scouting is usually very effective if done at the appropriate time. We recommend an economic threshold level of 5 percent. So if you scout 20 plants and you see an egg on just one of them, you're over the threshold and you're going to want to treat with an insecticide."
WBC caterpillars are highly vulnerable to insecticides. In one field Krupke visited in late June 2010, 50 percent of the corn plants were infested with the pest. The farmer ground-applied a pyrethroid insecticide.
"When we went back to that field in September, we could not find a single kernel on a single ear that was damaged," Krupke said. "The control level was 100 percent, and you won't hear that too often in pest management of insects."
For more information, visit the Purdue Extension corn insects scouting page at http://extension.entm.purdue.edu/fieldcropsipm/corn.php and click on the western bean cutworm bar.