A dark hole near the stem of a developing tomato can point to tomato fruitworm damage. The caterpillar feeds inside the fruit, so the damaged tomato may provide the first sign of an infestation before worms or adult moths appear around the plants.
Tomato fruitworms also feed on corn and peppers, with problems often appearing later in summer. Checking developing tomatoes around the stem can expose damage before more fruit becomes affected.
Look Near the Stem for an Entry Hole
Tomato fruitworm caterpillars chew into developing tomatoes and feed inside. An entry hole near the stem can turn dark, with caterpillar waste, called frass, collecting around the damaged area.
Fruit containing a feeding larva should be removed from the plant and discarded. Leaving an infested tomato in place gives the caterpillar time to finish feeding, emerge, and continue its life cycle.
Caterpillar Color Does Not Give You One Identification Clue
Tomato fruitworms, also called corn earworms, can appear green, brown, or red. Their diet can affect their color, making a single color description unreliable when checking plants.
Adult moths are brown or tan with a wingspan near 1 inch and tend to fly at night. Gardeners may see damaged fruit long before noticing the moth responsible for laying eggs around the crop.
Late Summer Brings More Risk in Some Gardens
Tomato fruitworms cause greater problems in parts of the southern United States where they can survive winter conditions. They can also reach northern growing regions, including areas into Canada, with pressure increasing later in the growing season.
July scouting can provide warning before tomato damage increases in August or September. Bait traps for adult moths can help indicate when moth activity has reached the garden.
Check Developing Fruit Before Damage Spreads
Inspect tomatoes on a regular schedule rather than waiting for fruit to ripen. Pay attention to the stem area, holes in the skin, frass, and fruit that begins showing damage without another clear cause.
Remove tomatoes containing larvae as soon as they are found. Do not put infested fruit beside the plants, where a caterpillar can leave the tomato and continue its development.
Natural Predators Can Reduce Fruitworm Numbers
Parasitic wasps and lacewings prey on garden pests and can help keep fruitworm populations down. Gardens supporting these beneficial insects may experience less pest pressure without requiring treatment for every caterpillar found.
When fruitworm numbers require control, Bacillus thuringiensis, or Bt, is one option used against caterpillars. Follow the product label for crop use, application timing, dose, and harvest restrictions.
Corn and Peppers Can Put Other Host Plants Close to Tomatoes
Tomato fruitworms do not depend on tomatoes alone. Corn and peppers also serve as host crops, giving the pest several food sources when these plants grow close together.
Garden layout can separate susceptible crops rather than concentrating tomato, pepper, and corn plants in one section. In regions where tomato fruitworms overwinter, turning garden soil after the growing season can expose or destroy pupae remaining in the ground.
