Classification
The cabbage white caterpillar is the larval stage of the small white butterfly, scientifically named Pieris rapae. It belongs to the order Lepidoptera (butterflies and moths) and the family Pieridae, a group that includes mostly white, yellow, and orange butterflies. Pieris rapae is among the most studied Lepidoptera species due to its role as a significant agricultural pest. While small and unassuming as adults, the larval stage can cause considerable damage to cabbage and other brassicas, making it of both ecological and economic importance.
Identifying Characteristics
The caterpillars of Pieris rapae are slender, velvety green, and typically measure about 1–1.25 inches (2.5–3 cm) at maturity. They are cryptically colored, blending in with the leaves of their host plants. The surface is covered in fine, short hairs, giving them a slightly fuzzy texture.
They are often distinguished by a faint yellow dorsal stripe and additional broken yellow lines running along the sides. These markings are subtle and enhance their camouflage among leafy greens. The adult butterfly is relatively small, with a wingspan of 1.5–2 inches (4–5 cm), white wings marked by black tips on the forewings and, in females, two black spots on each forewing.
Distribution, Migration & Habitat
The cabbage white is one of the most widespread butterflies in the world. Originally native to Europe and Asia, it was accidentally introduced to North America in the mid-19th century, and since then, it has spread across nearly every continent except Antarctica. It thrives in a wide variety of habitats, including gardens, farms, meadows, suburban areas, and roadsides.
Unlike monarch butterflies, cabbage whites do not undertake long-distance, seasonal migrations, but they are strong fliers and capable of dispersing widely. Their ability to reproduce quickly allows them to establish populations almost anywhere brassicas grow.
Predators and Threats
Cabbage white caterpillars face heavy predation and parasitism. Natural predators include birds, spiders, predatory beetles, and wasps. One of the most significant natural enemies is the parasitic wasp Cotesia glomerata, which lays eggs inside the caterpillar; the wasp larvae feed on the host internally before emerging, often killing it.
Additionally, fungal diseases and bacterial infections can reduce populations under favorable conditions. Humans also play a major role in controlling cabbage whites, using both organic methods such as handpicking and natural enemies, and synthetic insecticides in commercial farming. Despite these threats, their rapid breeding ensures persistent populations.
Lifespan of Adults
Adult cabbage white butterflies live relatively short lives, typically 2 to 3 weeks. During this time, their main focus is mating and reproduction. Females are capable of laying hundreds of eggs, usually singly on the undersides of leaves, ensuring widespread infestations.
Depending on climate, Pieris rapae may produce several generations per year—2 to 3 in cooler climates and up to 6 or more in warmer regions. This multivoltine life cycle makes them particularly resilient agricultural pests.
Host Plants & Diet
The cabbage white caterpillar’s diet centers around plants in the Brassicaceae (mustard) family, which includes many economically important crops. Common hosts include cabbage, broccoli, cauliflower, kale, Brussels sprouts, radishes, turnips, and mustard greens. The caterpillars chew irregular holes in leaves, often skeletonizing them, and may bore into the central growing tissues, stunting or killing young plants.
While the larvae are strictly herbivorous, adults are nectar feeders, commonly visiting flowers such as dandelions, clovers, and asters. Their dual feeding roles highlight an ecological contrast: destructive larvae that damage crops, and pollinating adults that support plant reproduction.
Lifecycle of Cabbage White Caterpillar (Pieris rapae)
Egg Stage
The cycle begins when adult female butterflies lay tiny, elongated, pale yellow eggs on the undersides of host plant leaves. Each egg is about 1 mm long and is usually laid singly rather than in clusters. A single female can lay hundreds of eggs, ensuring widespread infestations. The eggs typically hatch in 3 to 7 days, depending on temperature. Warmer conditions accelerate development, while cooler weather slows it down.
Larval (Caterpillar) Stage
Upon hatching, the larvae begin feeding immediately on the tender leaf tissue. The caterpillars go through five instars (molting stages), during which they grow from just a few millimeters to about 1–1.25 inches (2.5–3 cm) long. They are green with a velvety appearance, faint yellow striping, and covered in fine hairs that help camouflage them against leafy host plants. This stage lasts around 2 to 3 weeks. During this time, they are highly destructive, feeding on cabbage, broccoli, kale, cauliflower, and other brassicas, often skeletonizing leaves or burrowing into growing tissues.
Pupal (Chrysalis) Stage
When fully grown, the caterpillar stops feeding and attaches itself to a vertical surface, such as a plant stem, wall, or fence, using silk threads. It then transforms into a chrysalis (pupa). The pupa is usually green or brown, angular in shape, and blends well with its surroundings, offering some protection from predators. The pupal stage lasts about 1 to 2 weeks in warm weather. In colder climates, pupae may overwinter, delaying emergence until spring.
Adult (Butterfly) Stage
From the chrysalis emerges the adult cabbage white butterfly, with a wingspan of 1.5–2 inches (4–5 cm). Adults are white with black-tipped forewings; females also have two black spots per forewing, while males have just one. Adults live for 2 to 3 weeks, during which they mate and reproduce, continuing the cycle. Their diet consists of nectar from various flowers, including clover, dandelion, and asters, making them both pollinators and agricultural pests through their larvae.
Generations per Year
The number of generations varies with climate. In cooler regions, there may be 2 to 3 generations per year, while in warmer climates, there can be 4 to 6 or more, allowing populations to grow rapidly. This adaptability is one reason Pieris rapae has become one of the most successful butterfly species worldwide.