Subsequent western spread of this pest has increased its range throughout much of the eastern and mid-western United States. The European corn borer overwinters in Minnesota as late instar larvae inside corn stalks, weeds, and detritus. Larvae have dark spots and are cream colored, without stripes or spines. Larvae can be found in whorls, in the midribs of leaves, and in the silk and ears of infested plants. In addition, older larvae can be found inside corn stalks, usually in the lower half of the plant.
Females are lighter in color than males, and have brown wavy bands on their wings.
After mating, females will begin laying egg masses of 5-50 eggs on the underside of corn leaves. First generation egg masses are often smaller than later generation egg masses. Females lay up to 500 eggs in their lifetime, usually within 6 days after mating. Eggs are originally white, but will show black spots as the larvae mature inside. Life Cycle European corn borer typically has two generations per year in southern Minnesota.