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Garden pests
Cabbage white caterpillars
Pieris rapae and Pieris brassicae · Insect
Also called imported cabbageworm (North America), small white (UK and Europe), large white (Pieris brassicae) (UK and Europe), great white butterfly (Pieris brassicae) (New Zealand).
Illustration
Velvety green caterpillars that chew holes in cabbages, broccoli, kale and other brassicas, and burrow into the hearts. Cover plants with fine netting, check leaves for yellow eggs, and pick the caterpillars off by hand.
How to spot it
- Velvety green caterpillars up to about 3 cm long, with a faint yellow stripe down the back (small white).
- Hairy yellow-and-black caterpillars feeding in groups (large white, in the UK and Europe).
- Tiny yellow, bullet-shaped eggs under the leaves, laid singly (small white) or in clusters (large white).
- Ragged holes in the outer leaves, caterpillars inside the hearts, and droppings (frass) left on the leaves.
- White butterflies with black spots on the wings flying around the plants.
Easily confused with
Diamondback moth caterpillars
Much smaller, about 1 cm, and often leave see-through 'windows' in the leaves.
Cabbage moth and cabbage looper caterpillars
Smooth, without the velvety hairs; the cabbage looper arches its back into a loop as it walks.
Slugs and snails
They leave slime trails, not droppings.
Where it's a problem
- United Kingdom/Europe: Both the small white and the large white are common on brassicas, with two overlapping generations active from May to October.
- North America: Called the imported cabbageworm. It was accidentally introduced around 1860 and is one of the most damaging pests of the cabbage family.
- Australia: The small white was first recorded in Melbourne in 1929 and is now probably the most common butterfly in Sydney.
- New Zealand: The great white (large white) butterfly was found in Nelson in 2010 and later eradicated. Report groups of caterpillars or clusters of eggs on brassicas or cresses to MPI on 0800 80 99 66.
What to do
- Cover brassicas with fine netting or fleece from planting, held clear of the leaves and tucked in at the edges, so butterflies can't lay eggs.
- Check under the leaves every few days and rub off the yellow eggs.
- Pick the caterpillars off by hand, looking deep in the hearts too.
- Welcome the tiny parasitic wasps that attack the caterpillars: small yellow cocoons clustered by a dead caterpillar mean they're at work.
- Keep checking all season, as generations overlap (May to October in the UK).
If you use an insecticide, choose one labelled for cabbage white caterpillars and follow the label and local rules.
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Sources
- RHS: Cabbage caterpillars
- Utah State University Extension: Caterpillar pests of brassica vegetables
- University of Maine Cooperative Extension: Imported cabbageworm
- NZ Department of Conservation: Great white butterfly
- Australian Museum: Cabbage white butterfly
- RHS: Slugs and snails
Facts checked Sunday 27 September 2026. General guidance only: follow your local council, agency and product label.