Cabbage Butterfly of Cauliflower

One of the most disheartening sights in the vegetable garden is your otherwise flourishing plants full of holes, or the leaves chewed down to their stems. The Cabbage Butterfly may be a beautiful and excellent pollinator, but as caterpillars or larvae, unfortunately, they are one of the most destructive pests in cruciferous vegetable gardens. They can do a lot of damage in a short time. They tend to be most active in late summer and early autumn, right when many garden crops are starting to get bigger.

How to Identify Cabbage Butterfly?

There are 2 species of Cabbage Butterfly:

• Pieris rapae, also known as the small white, the small cabbage white, or the white butterfly, is a small to medium-sized butterfly with a wingspan of 32–47 mm (1.3–1.9 in). The upper side of its wings is creamy white with black tips on the forewings and one or two black spots in the center (depending on the sex). The underside is yellowish with black speckles.

• Pieris brassicae, also known as the large white, the large cabbage white, or the cabbage moth, is a larger butterfly with a wingspan of 50–63 mm (2.0–2.5 in). The upper side of its wings is white with black tips on the forewings and a black spot near the front edge. The underside is pale yellow with black veins and spots.

Life Cycle of Cabbage Butterfly

Both species have similar life cycles and behaviors. They lay their eggs on the undersides of leaves of brassica plants, usually in clusters. The eggs hatch into green caterpillars that feed on the leaves, causing holes and damage. The caterpillars then pupate in silken cocoons attached to the plants or nearby objects. The adults emerge after about two weeks and feed on nectar from various flowers. They can have several generations per year, depending on the climate and availability of food plants.

Damage caused by Cabbage Butterfly

The damage caused by these butterflies to cauliflower crops can be severe, especially during the primordial stage (10–20 days after planting) and the curd formation stage. The caterpillars feed on the leaves, making holes and skeletonizing them. They also bore into the growing tip and the curds, making them unfit for consumption and market. The damage can reduce the yield and quality of the crop significantly.

How to Control and Prevent Cabbage Butterfly?

Cultural control:

• Use fine-mesh netting in the nursery and main field to prevent the butterflies from reaching the crop and laying eggs.

• Collect and destroy eggs or caterpillars manually by hand, usually on the underside of the leaves. Rotate crops and avoid planting brassicas in the same area more than once every three or four years.

• Intercrop cauliflower with other plants that repel or distract the butterflies, such as marigold, mint, etc.

Biological control:

• Use natural enemies of these butterflies, such as egg parasitoids (Trichogramma spp.), larval parasitoids (Brachymeria spp., Eriborus spp., Cotesia spp., Apanteles spp.), and predators (ladybugs, lacewings, spiders).

• Use biopesticides based on Bacillus thuringiensis (Bt), a bacterium that kills caterpillars by producing toxins in their gut. Apply Bt when caterpillars are young and before they cause serious damage to the crop.

Chemical control:

• Use selective insecticides that are less harmful to natural enemies and pollinators, such as neem oil, pyrethrum, or spinosad.

• Apply insecticides only when necessary and follow label instructions carefully.

• Avoid spraying during flowering to protect bees and other beneficial insects.

• Rotate insecticides with different modes of action to prevent resistance development in the butterflies.