Controlling Cabbage Loopers in the Vegetable Garden

Cabbage loopers are green caterpillars with white stripes, up to 2 inches long, that devour brassicas (cabbage, broccoli, cauliflower, kohlrabi, collards) and also attack potatoes, tomatoes, spinach, and cucumbers. They're the larvae of white cabbage butterflies. Look for them spring through fall on leaf undersides.

Control Strategies

Row covers: Use floating row covers in spring to prevent egg-laying. Remove when plants get large or temperatures rise.

Hand-picking: Drop caterpillars into soapy water for small infestations.

Fall cleanup: Remove debris and till soil to destroy overwintering pupae.

Attract beneficials: Plant marigolds, calendula, sunflowers, daisies, alyssum, or dill to draw parasitic wasps and predators.

Bt (Bacillus thuringiensis): This natural bacterial spray kills caterpillars only. Considered organic by many gardeners.

Insecticidal soaps: Effective but require frequent reapplication; don't kill eggs.

Insecticides: Various products work; follow label instructions.