The Painted Lady butterfly, Vanessa cardui, is a widely distributed insect found across nearly every continent, excluding Australia and Antarctica. These medium-sized butterflies are recognized by their distinctive orange, black, and white patterned wings. Beyond their visual appeal, Painted Ladies are also known for their remarkable migratory patterns, undertaking some of the longest butterfly migrations globally, spanning thousands of miles.
What Caterpillars Consume
Painted Lady caterpillars are herbivorous, feeding on a range of host plants for their growth and development. Their diet primarily consists of leaves from plants within the Asteraceae (or Compositae) and Malvaceae families. Preferred host plants include various types of thistles, such as Canada thistle, spear thistle, tall thistle, and swamp thistle. They also commonly consume mallows, hollyhocks, and asters.
These caterpillars are voracious eaters, consuming significant quantities of foliage. They may also feed on plants like sunflowers, calendula, burdock, and various legumes, including alfalfa and clover. Caterpillars often create silken nests by tying leaves together, providing shelter while they feed. The nutritional content of these host plants is essential for their development into adult butterflies.
What Adult Butterflies Feed On
Adult Painted Lady butterflies primarily feed on nectar, which fuels their flight muscles. They are generalist feeders, visiting over 100 different kinds of flowering plants, but prefer taller plants (3-6 feet high) within the Asteraceae family. Common nectar sources include:
- Asters
- Thistles
- Zinnias
- Cosmos
- Blazing star
- Joe-Pye weed
- Purple coneflower
- Ironweed
- Calendula
- Sunflower
- Milkweed
- Red clover
- Butterfly bush
Beyond nectar, adult Painted Ladies occasionally supplement their diet with other liquid sources like tree sap, rotting fruit juices, or animal waste. Their specialized mouthpart, a long, tubular proboscis, allows them to reach deep into flowers. This proboscis is typically coiled when not in use, extending when the butterfly is ready to feed.
The Ecological Importance of Their Diet
The feeding habits of Painted Lady butterflies contribute to ecological processes. As adult butterflies move between flowering plants to collect nectar, they inadvertently transfer pollen, facilitating plant reproduction. This pollination service supports the health and genetic diversity of various plant species, including wildflowers and some fruit trees.
The caterpillars’ consumption of specific plants, particularly thistles, can also affect local plant dynamics. Their migratory behavior, fueled by their diet, allows them to spread pollen across vast geographical areas. The energy derived from their food sources is important for successful reproduction and migration. These butterflies also serve as a food source for animals, including birds, bats, and spiders.