WSU Extension

Hortsense

Broccoli, Cole crops
 
Disease
Black rot 
Clubroot 
Downy mildew 
Oedema 
Insect
Aphids 
Cabbage maggot 
Flea beetles 
Imported cabbageworm 
Loopers 
Thrips 



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Caption: Imported cabbage worm and damage on cabbage
Photo by: A.L. Antonelli
  
Broccoli, Cole crops : Imported cabbageworm
(revision date: 5/18/2015)


Biology
The imported cabbage worm 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

Non-Chemical Management
  • 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.
Select non-chemical management options as your first choice!

Chemical Management

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.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Azamax Botanical Insecticide, Miticide, & Nematicide [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 71908-1-81268
  • Bonide Captain Jack's Deadbug Brew R-T-U [Organic]
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 4-472
  • Bonide Eight Insect Control Garden & Home R-T-U
    Active ingredient: permethrin  |  EPA reg no: 4-406
  • Bonide Thuricide BT Conc
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 4-226
  • Bug Buster-O [Organic]
    Active ingredient: pyrethrins  |  EPA reg no: 1021-1771-54705
  • Bull's-Eye Bioinsecticide
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 62719-314-56872
  • ferti-lome Dipel Dust
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 7401-290
  • Safer Brand Caterpillar Killer for Trees, Shrubs & Vegetables Conc II [Organic]
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 70051-106-42697
  • Safer Brand Caterpillar Killer/Trees, Shrubs, & Vegetables Conc
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 42697-23
  • This list may not include all products registered for this use.
Images

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Caption: Imported cabbage worm and damage on cabbage
Photo by: A.L. Antonelli
Caption: Imported cabbage worm adult
Photo by: A.L. Antonelli