It is often referred to as the Cabbage White because its caterpillars feed on crucifers, members of the Brassicae family of vegetables, and can be a pest to both commercial farmers and garden vegetable growers.
For vegetable growers concerned about damage to vegetables information on effective organic preventative measures can be seen below.
Other caterpillars of moths and butterflies that gardeners may find in their vegetables.
Identification of the Cabbage White Butterfly
It is most easily identified from other common white butterflies – The Small White, Green-veined White and female Orange-tip Butterfly by its larger size, having a wingspan of up to 55mm and the extensive black tips to its forewings.
The female Large White butterfly has two large black spots on both sides of each forewing which are absent from the upper surface of the males.
Caterpillar food plants of the Large White Butterfly
The butterflies are also attracted to the brightly coloured garden nasturtiums which some vegetable growers plant as a companion plant in an effort to attract the butterflies away from their brassica crops.
Flight period of the Cabbage White Butterfly
Most eggs are laid during July and August when the numbers of resident butterflies may be increased significantly by migrants arriving from Europe.
This also happens to coincide with maturing brassica crops.
Identification of Large White Butterfly eggs
The egg clusters are yellow and can easily be seen against the green leaves.
The eggs hatch within 14 days.
Identification of the Large White Butterfly caterpillar
The caterpillars extract mustard oil from their food plants which make them unpalatable to birds. They give off a mustardy smell which combined with their bold colouring acts as a warning to predators.
They grow rapidly, shedding their skins four times and becoming generally darker with fewer yellow markings.
The caterpillars are heavily parasitised by the tiny Ichneumon Wasp, Apanteles glomeratus.
When fully grown after about four weeks the caterpillars stop feeding and leave the food plant to look for a suitable place to pupate.
Identification of the Large White Butterfly Chrysalis
Butterflies from early broods will emerge in about 14 days but later broods will over winter as a chrysalis, emerging in March or April.
However, many butterflies do not emerge having been parasitised.
Feeding signs of the Cabbage White caterpillar
Slight fenestration of the leaves will appear soon after the caterpillars first emerge which is shortly followed by small holes as the caterpillars grow rapidly.
Within two weeks large areas of leaves will be reduced to veins and by the time the caterpillars are fully grown whole plants can be stripped of all leaves leaving just the stalk.
How to stop vegetable damage by the Large Cabbage White Butterfly
The most reliable and least labour intensive preventative measure is to stop the female butterfly from laying her eggs on the vegetables. This can be done by suspending one inch mesh netting over the bed.
Although netting off is highly effective against Cabbage White Butterflies smaller insect pests such as the Diamond-back Moth (shown), The Cabbage Moth, Silver Y Moth and many species of fly and Sawflies will not be prevented from laying eggs on the vegetables.
Organic ways of preventing Cabbage White caterpillar damage
The yellow clusters of eggs are easy to see on the underside of the leaves and can be easily scrapped off.
Clusters of recently hatched caterpillars are also not difficult to find and can be spooned off.
Larger caterpillars can be picked off wearing gloves and are easily located by damaged leaves and frass.
Does companion planting prevent work?
However, although the female Cabbage White has been shown at times to favour laying her eggs on these brightly flowering plants she does not seem to do this exclusively.
It also seems likely that having Nasturtiums in the garden will attract more butterflies from neighbouring gardens and allotments.
The use of Pesticides to eradicate Cabbage White caterpillars
It is very easy to upset the natural balance of nature by using chemical pesticides that kill all insects.
The parasitic wasp Apanteles glomeratus kill a high proportion of Large White Butterfly caterpillars and there are many beneficial insects such as ladybirds that help control Aphids, Mites and other caterpillar vegetable pests.