Royal Alberta Museum: Invertebrate Zoology - Bug Facts

[Caterpillars and Other Immature Insects]

Fact Sheets: Commonly Observed and Asked About Insects and Spiders Found in Alberta

Cabbage White (Pieris rapae)

Cabbage White resting on a leaf
Credit: Terry Thormin

INTRODUCTION

The Cabbage White is an introduced species from Europe. It is also, unfortunately, a serious pest on a variety of garden plants in the mustard family such as cabbage, cauliflower and broccoli.

IDENTIFICATION

This is a white butterfly with a wing spread of about 5 cm. Males have a dark spot on the hind wing right near the leading edge, a dark spot in the middle of the front wing and a dark tip to the front wing. They also have some yellow scaling on the underside of the hind wing. Females have similar, although generally paler, dark markings and have a dark mark on the front wing along the trailing edge. Some summer individuals may be almost completely lacking the dark marks. The caterpillars are green with narrow yellow lines running down the back and sides.

DISTRIBUTION

This butterfly is found throughout Alberta and is distributed throughout North America south of the 60th parallel. It is also found in Europe, Asia and North Africa and is introduced in Australia.

TIME OF YEAR

In Alberta adults have three generations a year and can be found from April to October. There are even records as late as November 16.

HABITAT AND HABITS

This is a butterfly of cultivated areas, weedy areas and backyards. It can be found wherever its larval food plants, both domesticated and wild members of the mustard family, are found. At times it is a serious pest in backyard vegetable gardens and in farmers' crops. It overwinters in the pupal stage.

SIMILAR SPECIES

The Mustard White (Pieris napi) is a very similar species that is also closely related. It lacks the dark spots that the cabbage butterfly has but has dark scales along the veins, especially on the underside of the hind wing. There are several other species of white butterflies in Alberta, including the Western White (Pontia occidentalis), three species of marbles, and several species of sulphurs that have white female forms.

COMMENTS

When people see the Cabbage White they often think it is a moth as it is not very colourful. Of course, it is a butterfly, but in a sense they are right, as butterflies are just a group of moths. As stated earlier, the caterpillars can do considerable damage to any crops in the mustard family. We are not about to recommend control measures for commercial farmers and we certainly will not suggest any insecticide uses on this web site. For the home gardener though, a few suggestions may help. Often if an outbreak is not too serious, caterpillars can simply be picked off infected plants by hand. One can also reduce the next generation by destroying any unwanted plants and digging up the garden. Destroying any nearby wild mustard plants will also help.

Note: We cannot provide advice on controlling insect pests. If you need more information beyond what has been provided here, we suggest you either search further on the web, or talk to a local exterminator.

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Last update: August 6 2004