Leaves have tiny shot holes, tassels are broken, ear stalks are bent, and sawdust-filled holes are bored into the main stalks. Pinkish caterpillars with dark brown heads, two rows of brown dots, and indistinct reddish lengthwise stripes are inside the stalks or ears.
At the first sign of borers, apply an insectide that''s labeled for these pests, following the directions on the label. Destroy the plants at the end of the season. Avoid early planting.