Large White

Large White Pieris brassicae (Linnaeus 1758)

Family: Pieridae, subgroup Pierinae (The Whites)

Description

All photos above by Martin Partridge

Top photos and photo above right show females

Photo above left shows a male

The Large White is a very common but beautiful butterfly, also known as the Cabbage White.

Although it is well known it can be mixed up with the Small White because the two species may actually be similar sizes. However the largest Large Whites (usually second brood females) are larger than Small whites. The best feature to look at to tell the two species apart are the wing tips; usually Large Whites have black wing tips with the black curving over the top edge of the forewing whereas Small Whites have more greyish wing tips.

Second brood summer Large whites are more strongly marked than spring adults.

The species has been seen as a pest in the past and still is to many people, because of it using the cabbage family as larval food. Chemical pesticides are often used against the larvae and some people plant nasturtiums to encourage it away from their cabbages. The fact that it is very common despite being disliked by many people shows how robust the species is.

Habitat

This species can be found almost everywhere in the UK though it prefers lowland to high exposed ground. It can be seen in almost every habitat, including gardens, wastelands and farmland.

Large Whites have been recorded laying on over 60 different species of wild cruciferous plants and many types of cultivated cabbage varieties, and it will nectar on many wild and cultivated flowers, especially buddleia.

Distribution

It is a very common resident, and regular immigrant, usually seen in any lowland tetrad and many higher ones, including as far north as Shetland. Counts can be incredibly high; in one day in August 2001 Filey Brigg Ornithological Group counted over 1500 on Filey's North Cliff (VC61). These may have been immigrants from across the North Sea

It is also widespread across the world, from North Africa up to Norway and across to the Himalayas.

Life Cycle

In the majority of years there are two broods (April to June then July to September) and in good years there is a partial third lasting into October.

The generations overlap so that the butterflies seem to be around continuously through the summer and this is also supplemented by immigrants from Europe. Arrivals from North Sea crossings may be localised and quite densely packed but have often thinned out by the time they get to Yorkshire. There may be some moves back south in the autumn.

Using their antennae, female Large Whites are able to detect the strength of mustard oil in potential larval foodplants and seek to choose plants with the greatest concentration. The oil (a burning irritant) makes larvae taste bad to predators, particularly birds, and so the caterpillars do not try to hide on the food plant, despite being quite obvious and visible.

Eggs are laid in batches of about 50 on a wide range of wild and cultivated cabbage family plants and are pale yellow when laid, eventually becoming a golden orange and hatching after one to two weeks. The larvae eat their eggshells, then the leaf on which they were laid, before moving on to other leaves or plants. They usually only eat the plant's outer leaves (compared to Small White larvae which mainly eat the inner leaves) and they grow to about four to five centimetres long (about two inches) through 5 moults. They are pale green and yellow with black spots and have a distinctive unpleasant mustard smell. They stay together as large group where possible.

When they are ready to pupate they walk away on their own looking for somewhere to pupate. They can go large distances and climb up to the eaves of house or up trees. They put a web of silken threads on the surface they have chosen and attach themselves with silken hooks and a girdle.

Pupae are variable in colour, usually in shades from green to brown, and speckled with black dots. The first spring brood spend about two to three weeks as a pupa but the second brood overwinter in this stage.

The butterfly emerges when the weather is warm enough, usually around the end of April in Yorkshire, although recent warmer years have also seen March sightings.

The species is often attacked by a tiny wasp Apanteles glomeratus. The wasp injects eggs just below the skin of the larvae, enabling the resulting wasp larvae to develop without killing their hosts until just before pupation. As many as 80 wasps may develop on each larva and these wasps may explain the year to year fluctuations in Large White numbers.


Photo above top right shows the fourth instar of caterpillars

Photo above left shows the final instar, stripping a broccoli plant

Photo above right shows a larva in the process of pupating on the side of a greenhouse - note the silken pad it has spun plus the silken girdle

Photos by Catherine Jones

Status

The species is not under threat.

Aberrations

Around 30 aberrations have been described, including a rare sulphur yellow variety ab pava Kane and a pink-tinged specimen ab cornea Gross-Smith.

With thanks to the Butterflies of Yorkshire edited by Howard M Frost

C Jones 04/01/21