Cabbage White Butterfly: ID, Damage, and Control

Faunalist Tip: Put the row cover on the day you plant, not the day you see butterflies. By the time cabbage whites are visibly working a bed, eggs have already been laid on the undersides of the leaves, and covering the plants then simply traps the caterpillars inside with the crop and excludes the parasitoid wasps that would have found them. Cover early or not at all.

What Are Their Natural Enemies?

Parasitoid wasps do most of the work. Cotesia glomerata and related species lay eggs inside cabbage white caterpillars, and the larvae emerge to spin clusters of small yellow cocoons on or beside the dying host, a sight familiar to anyone who grows brassicas. Parasitism rates in unsprayed gardens can be high.

Birds take both caterpillars and adults, with house sparrows, wrens, chickadees, and warblers all working brassica leaves, and paper wasps carry caterpillars back to their nests in quantity. Ground beetles, spiders, and predatory bugs take eggs and small larvae.

A viral disease also cycles through dense populations. Nucleopolyhedrovirus spreads rapidly when caterpillars are crowded and can collapse a local outbreak within weeks, leaving limp dark caterpillars hanging from leaves. That is the same class of natural control that limits many caterpillar populations, and broad-spectrum insecticides remove the predators and parasitoids while doing nothing about it. The guide to birds that eat caterpillars covers the bird side.

Should You Leave Cabbage White Caterpillars?

On brassicas you want to eat, no. On nasturtiums, ornamental kale, or wild mustard at a garden edge, there is a reasonable case for leaving them, since they feed birds and support the parasitoid wasps that then work your vegetable beds too.

The adults are also pollinators, and this is the part of the picture usually left out. Cabbage whites visit a wide range of flowers and are among the most numerous butterfly visitors in many gardens, and while they are less efficient than bees they contribute to pollination across the season and in cool weather when bees are inactive.

Where they do genuine harm is in commercial and home vegetable production, which is a real cost rather than a squeamish one. The workable position for most gardeners is to protect the crop physically and leave the butterfly alone elsewhere, rather than treating it as something to eliminate from the garden.

How Rare Is a Cabbage White?

Not remotely rare. It is one of the most abundant butterflies in North America, Europe, and much of Asia, present in gardens, farmland, roadsides, and city parks, and it is often the first butterfly seen in spring and the last in autumn.

The spread was remarkably fast. First recorded near Quebec around 1860, probably arriving with shipped produce, cabbage whites reached the Pacific coast within about thirty years, helped by a diet that matched the crops being planted across the continent and by the mustard-family weeds that grow in every disturbed field.

Its success has come partly at the expense of natives. The native mustard white and West Virginia white have declined in areas where cabbage whites are abundant, partly through competition and partly because both native species lay eggs on garlic mustard, an invasive plant that their caterpillars cannot survive on. The Xerces blue guide covers the other end of that story.

What Does Seeing One Mean?

White butterflies carry the strongest folklore of any colour, widely read as spirits, souls, or messages from the dead, and in several European traditions a white butterfly is taken specifically as a departed loved one making contact. Purity, peace, and new beginnings are the other common readings.

Seasonal omens attach to the first white butterfly of the year, and they contradict each other by region. In parts of England the first butterfly of spring being white meant good luck for the year; in other versions it meant the opposite, and in some Scottish and Irish traditions white butterflies were associated with the souls of children.

None of this is specific to the cabbage white, which has no folklore of its own and was not present in North America when most of this symbolism formed. What a sighting reliably means is that something in the mustard family is growing nearby, cultivated or wild. The guide to a butterfly landing on you covers the encounter symbolism.

How Long Do They Live?

About three weeks as an adult, and roughly a month from egg to adult in warm weather. Eggs hatch in four to eight days, the caterpillar feeds through five instars over ten to twenty days, and the chrysalis takes one to two weeks.

The chrysalis is where the year ends. The final generation overwinters as a chrysalis attached to a fence, wall, shed, stem, or plant debris, coloured green or brown to match the surface, and adults emerge in early spring, often flying on the first warm days of March or April before most other butterflies are active.

That overwintering habit means garden structures matter. Chrysalides on a fence or under a windowsill are easy to miss and are frequently scraped off during spring cleaning, and greenhouse frames are a favourite site. Leaving them is the simplest thing anyone can do either for or against the species, depending on how they feel about it. The painted lady guide covers a species that solves winter differently.

Frequently Asked Questions

How do you identify a cabbage white butterfly?

Small white butterfly with grey-black wingtips and black forewing spots, one on males and two on females, with a pale yellowish hindwing underside and a bouncing erratic flight.

Is the cabbage white butterfly a pest?

Yes, one of the most significant vegetable pests worldwide. Caterpillars eat cabbage, kale, broccoli, and other brassicas, and the frass packed into heads often ruins crops more than the chewing does.

What does the caterpillar look like?

Velvety green with a faint yellow line down the back and broken yellow side lines, up to about an inch, sitting along leaf midribs. Loopers arch their backs; cabbage whites do not.

How do you control cabbage whites?

Floating row cover from planting day is the most effective method, since brassicas need no insect pollination. Bacillus thuringiensis works as a spray, and hand-picking in the morning works on a small scale.

What are their natural enemies?

Parasitoid wasps above all, which leave clusters of yellow cocoons beside dying caterpillars, plus birds, paper wasps, ground beetles, and a virus that collapses crowded populations.

Are cabbage whites good pollinators?

They contribute, particularly in cool weather when bees are inactive, though they are less efficient than bees. In many gardens they are the most numerous butterfly flower visitor.

How long does a cabbage white live?

About three weeks as an adult and roughly a month from egg to adult. The last generation overwinters as a chrysalis on fences, walls, and stems, emerging on the first warm days of spring.