How to Identify Corn Worms on Tomatoes

The corn earworm, tomato fruit worm or Helicoverpa zea, is the larva of a large moth. When this insect lays its eggs on a tomato plant, the hatchlings can be numerous and can affect the quality and harvest of your favorite salad ingredient. This destructive insect lives almost everywhere in North America, according to the University of Florida. If you live north of the 40th latitude (Kansas, Ohio, Virginia, southern New Jersey and Washington state), you might not encounter this pest. It enters a dormant period during cold winters, but it is active year-round in warmer climates.

Things You'll Need

Magnifying glass
Flashlight

Butterfly net (optional)

Instructions

- 1
  Examine the leaves of your tomato plants periodically beginning in May and continuing through August. Look for earworm eggs, which are light green when the moth first lays them. Later, they turn yellow and finally gray. They are dome shaped and occur singly. Measuring only .2 inches in diameter, these eggs can be hard to spot, especially because they hatch within three or four days. Crush all eggs you find.
- 2
  Search your tomato plants for larvae. They can grow as long as 1-1/2 inches and their heads are orange or pale brown and show a pattern resembling a net. The body is pink, green, yellow, brown or black. The larvae can also have two dark stripes that run down the back.
- 3
  Kill the adult moths by searching for them at night with a flashlight. These insects are large, with a length of ¾-inch and a wingspan of 1-1/2 inches. Their color is tan, green or reddish brown. Use a butterfly net if you find it difficult to capture them by hand.
- 4
  Watch for damage to developing tomatoes and to other parts of plants, such as the leaves and stems. The earworms typically burrow into ripening fruit and leave a small hole, but soon depart in search of other tomatoes or plants in your garden they like to eat.

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