Cabbage Worms
Pest · Commonly affects: Cabbage, Broccoli, Cauliflower, Kale, Brussels sprouts, Collard greens
Cabbage worms are the caterpillar stage of the imported cabbage white butterfly (Pieris rapae), one of the most common pests of cole crops in home gardens across the United States. They matter because they feed heavily on the leaves and heads of cabbage-family plants and can quickly ruin an otherwise healthy crop if left unchecked.
How to identify it
Look for velvety, pale green caterpillars up to about one inch long with a faint yellow stripe running down the back; they blend in closely with leaf color and often rest along the midrib. The adult is a white butterfly with one or two black spots on each forewing that flutters over the garden during the day, and clusters of small, yellowish, bullet-shaped eggs may be found on the undersides of leaves. Dark green, crumbly droppings scattered on the foliage are a reliable sign that worms are present even when the caterpillars themselves are hard to spot.
Damage
The caterpillars chew ragged, irregular holes in leaves and bore into the developing heads of cabbage and broccoli, often working their way toward the center where they are hard to reach. Beyond the loss of leaf tissue, their droppings contaminate heads and florets, lowering quality and making harvested produce unpleasant to clean and eat.
Prevention
Rotate cole crops so they are not planted in the same bed year after year, and clean up and remove old plant debris at the end of the season to reduce overwintering pupae. Space plants properly and keep the soil healthy and evenly fed so plants grow vigorously and can better tolerate some feeding, and consider red or purple-leaved cabbage varieties, which make the green caterpillars easier to see and hand-remove.
How to manage it
The most effective home-garden control is floating row cover placed over the plants right after transplanting and kept in place through the season, since cole crops do not need pollinators; this physically blocks the white butterflies from laying eggs. Scout the undersides of leaves once or twice a week and handpick both eggs and caterpillars, dropping them into soapy water, and cut out any heavily infested leaves or damaged head tissue. Encourage natural enemies such as parasitic wasps, predatory beetles, and birds by keeping some flowering plants nearby, and water at the base of plants in the morning so foliage stays healthy without creating the damp, sheltered conditions that let feeding go unnoticed.
General guidance for US home gardens, focused on prevention and non-chemical control. For a confirmed diagnosis and options specific to your area, contact your local Cooperative Extension office. Page updated Aug 4, 2026.