(Heliothis zea)
This is the most serious pest of corn. It also attacks many other garden vegetables and flowers, and is also known as the tomato fruitworm and the cotton bollworm. The worm is the larva of a light gray-brown moth with dark lines on its wings. In the spring, the moth lays yellow eggs singly on corn silks and the undersides of leaves. The worms that hatch from these eggs feed on the new leaves in the whorls. This feeding doesn't reduce the corn yield, but the leaves that develop are ragged and the plant may be stunted. More serious damage is caused when the worms feed on the silks, causing poor pollination, and when they feed on the developing kernels. Worms enter the ear at the silk end, or they may bore through the husk. There are several generations a year. In the South, where these pests survive the winter, early and late plantings suffer the most damage. Adult moths migrate into northern areas, where late plantings are severely damaged. Uneaten parts of infested ears are still edible.
Once the worms are in the ears, insecticides are ineffective. In the future, dust plants with an insecticide containing carbaryl when 10 percent of the ears show silk. Repeat the treatment 3 to 4 times at intervals of 3 days. If the infestation continues, repeat as necessary until harvest.
Plant Care for Corn