Cabbage white butterflies are the caterpillars of both the small and large white butterflies (Pieris rapae and Pieris brassicae). Small white caterpillars are pale green with a body up to 2.5cm long, while large white caterpillars are 4cm and are yellow with black markings. The adult butterflies lay eggs from May to June and then July to September. This means you can find cabbage white caterpillars on your brassicas from late spring through to autumn.
Caterpillars eating holes in the outer and inner leaves of brassicas, with nasturtiums also being used.
Find it on
Brassicas and nasturtiums
Cover plants with horticultural fleece or fine netting to prevent butterflies reaching the leaves. Check plants regularly and pick off any caterpillars that do make it through. Grow nasturtiums as a sacrificial crop and move eggs and caterpillars from your brassicas to the nasturtium leaves. Spray young caterpillars as they hatch with the biological control Steinernema carpcapse.
With heavy infestations, use an insecticide based on pyrethrum (only use once a season on crops).