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Caterpillars on cole crops

Quick facts

  • Cole crops include cabbage, cauliflower, broccoli, kale, rutabaga, radish, turnip and collard.
  • The most common caterpillar pests of cole crops are imported cabbageworm, cabbage looper and diamondback moth.
  • The imported cabbageworm is the most common caterpillar in gardens.
  • All caterpillars feed between the large veins and midribs of cole crops.
  • Older, larger caterpillars cause the most feeding damage.
  • Treat caterpillars when they are still small and before they cause too much feeding damage.

How to identify caterpillars

Imported cabbageworm (Pieris rapae):

Adult butterflies are commonly seen flying around plants during the day.

  • Adults are white butterflies with black spots on the forewings.
  • Eggs are yellow and oblong, and are on both upper and lower sides of leaves.
  • Caterpillars can grow up to 1 inch in length and are velvety green with faint yellow stripes running lengthwise down the back and sides.
  • They move sluggishly when prodded.
A tiny, oblong, yellow egg on a leaf
Imported cabbageworm egg
 A fuzzy, green imported cabbageworm larvae on the surface of a leaf.
Imported cabbageworm larva
Light gray moth with a white furry body and long antenna feeding on the center of a flower
Imported cabbageworm moth

Cabbage looper (Trichoplusia ni):

Adults are nocturnal moths with a 1½-inch wing span.

  • Adult moths have mottled grayish brown wings.
  • A small silvery white figure 8 is in the middle of each of the front wings.
  • Eggs are creamy white, aspirin-shaped, and about the size of a pin head.
  • Adults lay eggs on the undersides of the lower leaves.
  • Caterpillars are pale green with narrow white lines running down each side.
  • Full grown caterpillars are about 1½ inches long.

Cabbage looper caterpillars have no legs in their middle sections and make a characteristic looping motion as they move across vegetation.

Yellow-colored, tiny, pin-point eggs on the underside of a leaf
Cabbage looper eggs
A green caterpillar arching its body as it moves on a leaf.
Cabbage looper larva
Grayish brown moth with four legs
Cabbage looper moth

Diamondback moths (Plutella xylostella):

  • Adult moths are nocturnal flyers.
  • Moths are light brown and slender.
  • The folded wings show a pattern of three white diamonds.
  • Eggs are laid near leaf veins on the leaf and are creamy-white and tiny.
  • Caterpillars are light green, tapered at both ends, and grow up to 1/3 inch long, much smaller than imported cabbageworms and cabbage loopers.
  • They wiggle vigorously when touched.
Thin, green caterpillar chewing a hole in a cabbage leaf
Diamondback moth larva
A slender, light-brown moth on a green leaf
Diamondback moth adult

Biology of caterpillars

All three species have similar life cycles.

  • Eggs hatch into caterpillars and then damage plants.
  • After feeding for weeks on cole crops, the larvae change into pupae in protected areas on the plants.
  • Then they emerge as adults.
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Damage

Irregular shaped holes on the leaves of a cole crop
Caterpillar damage on a young plant
  • Cole crops can tolerate some feeding damage.
  • Young seedlings and transplants are most susceptible to injury.
  • Severe defoliation of young seedlings and transplants can cause distorted growth or even death.
  • Extensive feeding can also prevent the head formation of cabbage, cauliflower and broccoli.
  • Older plants can tolerate some defoliation, with little effect on yield. Do not allow defoliation to exceed 30 percent of leaves.

The caterpillars of all three species feed between the large veins and midribs of cole crops.

Imported cabbageworm and cabbage looper feeding

Holes in the leaves of a cabbage plant
Caterpillar damage on older plant
  • Young caterpillars produce small holes in leaves that do not break through to the upper leaf surface.
  • Larger caterpillars chew large, ragged holes in the leaves leaving the large veins intact.
  • In cabbage, broccoli, or cauliflower, larger caterpillars crawl toward the center and leave large amounts of frass (fecal matter).
Velvety green caterpillars with holes and the leaves and small circular pieces of frass.
Imported cabbage worm frass and feeding damage
Brownish droppings of caterpillar on cauliflower florets
Caterpillar frass on cauliflower

Diamondback larva feeding

Purplish green cabbage leaf's underside with small sections where layers have been eaten, leaving the thin top layer of the leaf.
A diamondback moth feeding
  • Starts feeding inside the leaves and then moves to the outside of the leaves.
  • Eats all the leaf tissue except the upper layer, giving a windowpane look.

Managing caterpillars in cole crops in home gardens

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Managing caterpillars on cole crops on farms

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Authors: Marissa Schuh, horticulture IPM Extension educator, Jeffrey Hahn, and Suzanne Wold-Burkness, College of Food, Agricultural and Natural Resource Sciences

Reviewed in 2022

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