This insect is the same species as the corn earworm, but found on a different crop. Damage to ripening fruit of tomato, eggplant, peppers and okra by this insect ruins the fruit. Fortunately, damage is spotty and rare in Iowa.
Tomato fruitworm moths do not survive in Iowa through the winter, but instead arrive as migrants blown into the state from the southern U.S. each spring. The moths lay eggs on the host plants. Young larvae apparently feed unnoticed on foliage until green fruits are present. Fruitworms vary greatly in color from light green to brown. They are marked with alternating light and dark stripes running lengthwise on the body. There may be 2 or 3 generations of tomato fruitworms each summer.
Tomato fruitworms often move from one fruit to another as they feed, and one larva may damage several fruits without consuming the equivalent of a single tomato. Many more fruits are spoiled than are actually consumed. They attack green fruits and typically cause neat round holes through the skin on the side of the tomato.
As with other occasional pests of tomatoes, there is no special monitoring or treatment program for fruitworms. Carefully watch for feeding damage as fruits are expanding. Spray only when damage levels are intolerable. If damage were severe in Iowa like it is in other parts of the U.S., a weekly insecticide application from fruit set until the end of harvest would be used. Fortunately, fruitworm damage in Iowa is low and removing damaged fruit from the plant or sorting injured tomatoes during harvest provides adequate management.