Caterpillars
Caterpillar Facts
Common names: Large white, small white and green veined white butterflies, cabbage and diamond-back moth.
Scientific names: Pieris Crassicae, P. Rapae, P. Napi, Mamestra Brassicae, Plutella Xylostella.
Cabbage Caterpillars feed on all edible brassicas.
Cabbage Caterpillars are active from May to October.
Symptoms include:
- Sight of caterpillars on leaves
- Holes in the leaves
Holes are eaten in the outer leaves of all brassicas and damage may also be seen on the inner leaves of cabbages when the heart is cut through. Caterpillars and their excrement are often found on the plants.
Non-Chemical Treatments include:
- Picking off the caterpillars and eggs on sight
- Protecting plants with netting/mesh or fleece
- Encourage predators like birds and wasps
- Nematodes
Caterpillars are the larval stage of butterflies and moths. There are several species that feed on cabbages, other brassicas and other plants including turnip, swede, horseradish and nasturtiums.
About Caterpillars
Caterpillar Lifecycle
The pest overwinters as a pupa and emerges in late spring to lay groups of yellow conical shaped eggs on the undersides of brassica leaves such as cabbages, brussels sprouts, kale, swedes, nasturtiums and wallflowers. After a period of 14 days the caterpillars emerge and start feeding on the host plants.
The caterpillars moult as they grow and when fully fed the caterpillars seek crevices in sheltered places to pupate. There can be up to 3 generations per year, the first is on the wing in May-June, the second in August and the third in September-October. The adults can fly over distances of hundreds of miles and every summer the UK population is reinforced by new arrivals from the continent.
Three main species are:
Large White Butterfly (Pieris Brassicae)
Small White Butterfly (Pieris Rapae)
Cabbage Moth (Mamestra Brassicae)
Large Cabbage White Butterfly likes to lay its eggs in sheltered spots, so gardens are ideal. Its caterpillars are pale green, often with a yellow hue, and heavily dark-speckled. Look out for a strong, yellow line down the centre of their backs and light hairs.
Small Cabbage White Butterfly are velvety green, again with a yellow line down the middle of their backs. They are both about 3-4cm long when fully mature.
Cabbage Moths are plain grey-brown with some white markings. Flying at night, they are seldom noticed by gardeners. Their light-green/brown caterpillars are 4cm long when fully grown. Unlike the cabbage-white caterpillars, they do not have many hairs.
Diamond-Back Moths are elongated and narrow in shape, about 6mm long, with long antennae and white wing edges. When closed, the white marks form a rough diamond pattern. Its light-green caterpillars live on the leaf undersides in a web, and can reach 14mm long.
