Growing Degree Day (GDD) accumulations can help growers monitor stalk borer hatch and movement by using GDD accumulated with a developmental threshold of 41º F. Common stalk borer eggs typically begin to hatch at 575 GDDs. They wrap up first hatch and begin feeding on weeds and grasses at 750 GDDs. At 1,300 GDDs, the first 10 percent of caterpillars begin to move into the corn crop and scouting should begin. At 1,400 GDDs, 50 percent of the caterpillars will have moved into corn.
The chart offers stalk borer scouting recommendations.