Don Herbison-Evans (
The scientific name of this species is probably derived from the Greek word rapavi (rapavi) meaning 'radish', which is one of the food plants of the Caterpillar.
This velvety looking plain green Caterpillar is a similar colour to the leaves of many of its food plants. The caterpillar is an international pest on:
It seems to need food plants that contain Mustard Oil, so it feeds on most species of the family BRASSICACEAE, including :
It also will develop on a variety of plants from other families, including :
The Caterpillar, when mature, has a pale yellow line on the back, and a line formed of yellow spots on each side. It normally sits on the upper surfaces of leaves of its food plant in broad daylight. Its coloration is presumably an effective camouflage. It grows to a length of about 3 cms.
When the Caterpillar is fully grown, it creeps off: searching for a sheltered crevice in which to pupate. It usually crawls upwards in its search and if its search is unrewarded, may pupate on an exposed wall. It attaches itself at both ends of the body with silken pads, and also puts a loop of silk around its middle. It turns into an exquisitely sculptured angular form, like a broken but symmetrical piece of jade. The pupa may turn brown. Its final colour is influenced by the colour of its background. On light backgrounds, the pupa remains greener than on dark backgrounds.
In summer, the butterfly emerges after about two weeks. The upper surfaces of the wings are white with black tips to the forewings, and a faint black spot on the front margin of the hindwings. In the middle of each forewing, males have a single black spot.
Females have a pair of black spots on each forewing. The undersides of the forewings are similar to upper surfaces, except for the abscence of the black wing tips. The undersides of the hindwings are plain pale yellow. Butterflies from pupae which have been subjected cold temperatures in winter are much paler than summer forms from pupae that have stayed warm. Both sexes have a wingspan of about 4 cms.
The eggs are pale yellow and bottle-shaped, with a height of about 1.5 mm. They are usually laid singly on the underside of a leaf of a foodplant.
There is much confusion about the common names of this and other Caterpillars that feed on Cabbages, which in general is why scientific names were invented. Note that our Cabbage White Pieris rapae is quite different from the Cabbage Moth: Plutella xylostella, which is also a world-wide pest of Cabbages.
Although a common pest over the whole of Australia, the Cabbage White is not a native to Australia. There are in fact no Australian native members of the genus Pieris. The species Pieris rapae appears to have originated in Europe, where it is called the Small White, to distinguish it from Pieris brassicae, the Large White, the Caterpillar of which also feeds on Cabbage. In Europe, the Large White is plentiful, and is also confusingly known as the Cabbage White. Although the Large White has appeared in North America, south-east Asia, and Japan, so far there is no sign of the Large White appearing in Australia. Our Cabbage growers hope it will stay that way.
In Japan, our Cabbage White is known as the European Cabbage Butterfly. In North America, it is known as the Imported Cabbageworm. or else as the Cabbage Butterfly. Our Cabbage White has spread around the world in the wake of European colonisation and cultivation of cabbages. It was first found outside Europe in Canada in 1860. It had spread to California by 1883, Hawaii by 1898, and it reached Melbourne in 1929. The species spread across the length and breadth of Australia reaching Perth in 1943. In 1980, it was featured on Japanese postage stamps :
The pupa of Pieris rapae has been found to contain a carcinogenic chemical Pierisin.
The damage caused by Pieris rapae to crops has provoked various government agencies to try and control the species. The control agents still being investigated include:
The behaviour of the butterfly is also being extensively studied.
Nevertheless, the Cabbage White is still probably the commonest butterfly in Sydney and Melbourne gardens.
Further reading :
Michael F. Braby,
Butterflies of Australia, CSIRO Publishing, Melbourne 2000, vol. 1, pp. 343-344.
(updated 21 December 2009)