Large, ragged holes chewed in cabbage, broccoli or kale leaves, with velvety green caterpillars on them, are imported cabbageworm - the larva of the white butterflies that lay on cole crops.
Promising · ignored, it still works, just worse · the planner suggests it
How it works
The adult is a white butterfly with black spots on its forewings that lays its eggs on cole crops. The caterpillars grow to about an inch, velvety green with faint yellow stripes, and the larger ones chew large, ragged holes in the leaves, leaving the big veins.
What to do about it
Handpick the caterpillars into a pail of soapy water. To stop the eggs being laid, cover the crop with floating row cover from seeding or transplanting until harvest. Where caterpillars are many and still young, a Bt product is an option.
How much it matters: No loss figure is invented. The source says young seedlings and transplants are hurt most; older plants tolerate some chewing. The rule advises and never blocks.
The evidence
Evidence: confirmed against 1 source in the research-based literature.
the source
UMN Extension, 'Caterpillars on cole crops', extension.umn.edu/garden-and-home/yard-and-garden/yard-and-garden-insects/caterpillars-on-cole-crops (fetched in-container 2026-09-25, read 2026-09-25): 'Adults are white butterflies with black spots on the forewings.'; 'Caterpillars can grow up to 1 inch in length and are velvety green with faint yellow stripes running lengthwise down the back and sides.'; 'Larger caterpillars chew large, ragged holes in the leaves leaving the large veins intact.'; 'Handpick and drop the caterpillars into a pail of soapy water to kill them.'; 'Floating row covers made up of lightweight all-purpose garden fabric keep the adult moths from laying eggs on plants.'; 'Fit the row covers directly over garden plants or over metal hoops/wooden frame to cover the cole crops at seeding or transplanting.'; 'When diamondback moths are the dominant caterpillar found, or when other caterpillars are found while they are still young, consider using a Bt product.'
Where this rule stops
Scoped by applies_to.species to Brassica oleracea (cabbage, broccoli, kale, cauliflower, Brussels sprouts, kohlrabi), so it surfaces on that plant page and answers the "ragged holes and green caterpillars" sign in the Something's-wrong picker (symptoms.ts). It gates nothing. The source names three caterpillars on cole crops; this rule names the imported cabbageworm, the one it describes as velvety green, and its remedies serve the other two as well.
Plants this fires on
Change history
Every change to this rule is one commit. This is what the project's version history records — the date and the reason — not a summary of it.
- corpus(another rule here): new rule, Promising, verified - imported cabbageworm on cole crops
Cite this page
Milpa Gardens. "Large, ragged holes chewed in cabbage, broccoli or kale leaves, with velvety green caterpillars on them, are imported cabbageworm - the larva of the white butterflies that lay on cole crops." Evidence grade: Promising. https://milpa.garden/rules/large-ragged-holes-chewed-cabbage-broccoli-kale/
A garden-planning corpus: every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.