Broccoli, Cole crops: Imported cabbageworm

Biology

The imported cabbageworm is the larval stage of the cabbage butterfly. The adult butterfly has white wings, with black tips and spots on the forewings. Wingspan is about 1 1⁄2″. Eggs are laid in the spring on the leaves of host plants, which include cole crops such as broccoli and cabbage, as well as radish, turnip, and nasturtiums. The caterpillars are green with faint yellow stripes along the back and sides. They feed on the leaves, chewing irregular holes in the leaf tissues. Mature caterpillars are about 1″ long and may also feed in the center of cabbage heads. Black pellets of frass (excrement) are often present on the leaves. The caterpillar pupates in a pale green chrysalis which may be attached to any convenient object in the garden. Three to five generations may occur in a single season.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Cover crops with floating row covers or screen cages to prevent egg-laying by adult butterflies.
• Hand-pick any caterpillars found on leaves.
• Pick and destroy any pupae found.
• Natural enemies of caterpillars include predacious beetles, parasitic wasps, and birds. Avoid use of broad-spectrum insecticides when possible to conserve beneficial insects.
• Remove debris which may shelter pupae.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• Use product according to label instructions.
• Read the product label for timing between last application and harvest.
• Apply in spring about 10 days after flights of mating pairs are observed.
• Use a spreader-sticker with liquid Bt formulations.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

• Bonide Captain Jack's Deadbug Brew R-T-U [Organic]
  Active ingredient: spinosad (spinosyn A+D) [EPA registration number: 4-472]
• Bonide Thuricide BT Concentrate
  Active ingredient: Bacillus thuringiensis subsp. kurstaki [EPA registration number: 4-226]
• Bug Buster-O [Organic]
  Active ingredient: pyrethrins [EPA registration number: 1021-1771-54705]
• ferti-lome Dipel Dust
  Active ingredient: Bacillus thuringiensis subsp. kurstaki [EPA registration number: 7401-290]
• Safer Brand Caterpillar Killer for Trees, Shrubs and Vegetables Concentrate II [Organic]
  Active ingredient: Bacillus thuringiensis subsp. kurstaki [EPA registration number: 70051-106-42697]
• Garden Safe BT Worm and Caterpillar Killer
  Active ingredient: Bacillus thuringiensis subsp. kurstaki [EPA registration number: 9688-294-39609]
• This list may not include all products registered for this use.

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