The Black Swallowtail butterfly (Papilio polyxenes) is a beautiful species commonly found in gardens across North America. Its caterpillar, often referred to as the Black Swallowtail caterpillar, is known for its striking green and black appearance, with vibrant orange spots. To transform into a butterfly, this caterpillar must feed on specific plants that provide the nutrients needed for growth. Understanding which plants these caterpillars eat is essential for gardeners who wish to support these fascinating insects while fostering a healthy garden ecosystem.
In this article, we’ll explore the plants that Black Swallowtail caterpillars prefer and how you can incorporate them into your garden.
The Black Swallowtail Caterpillar: An Overview
Lifecycle of the Black Swallowtail
The Black Swallowtail caterpillar undergoes several stages of development, from egg to caterpillar to pupa and, eventually, to butterfly. The journey begins when the female butterfly lays her eggs on suitable host plants. Upon hatching, the caterpillars begin feeding on the plant leaves, growing rapidly over time. After several molts, the caterpillar will transform into a pupa (or chrysalis), where it will undergo metamorphosis into the adult butterfly.
Identification of the Black Swallowtail Caterpillar
Young caterpillars are green with black bands and orange spots, making them look somewhat like bird droppings—a tactic that helps them avoid predators. As they mature, they grow larger and their color may darken, becoming predominantly green with black markings. When disturbed, the caterpillar can release an orange, forked organ known as the osmeterium, which is used as a defense mechanism against predators.
Host Plants for Black Swallowtail Caterpillars
Parsley (Petroselinum crispum)
Parsley is one of the most well-known host plants for Black Swallowtail caterpillars. They prefer the flat-leafed variety, although the curly-leafed version can also be consumed. Parsley is not only beneficial for the caterpillars but can also be grown in your garden for culinary use. The caterpillars will quickly strip the leaves, so if you’re hoping to support them, consider growing a patch of parsley specifically for them.
Dill (Anethum graveolens)
Dill is another favored host plant for Black Swallowtail caterpillars. This herb, which has feathery, aromatic leaves, attracts caterpillars in droves. Dill is commonly used in cooking, particularly in pickles, but in your garden, it also serves as a great food source for these insects. If you want to cultivate dill specifically for the caterpillars, try to leave a few plants unsprayed with pesticides.
Fennel (Foeniculum vulgare)
Fennel, with its aniseed flavor and aromatic foliage, is an excellent host plant for Black Swallowtail caterpillars. The plant’s feathery leaves are particularly attractive to the caterpillars, and like dill, fennel is also edible for humans. While fennel can grow quite large, it’s advisable to plant it in a location where it won’t overwhelm other garden plants. Fennel’s delicate flowers also attract other pollinators, enhancing the biodiversity of your garden.
Queen Anne’s Lace (Daucus carota)
Queen Anne’s Lace, a member of the carrot family, is a favorite of Black Swallowtail caterpillars. Its lacy white flowers are iconic, and its leaves are commonly used by the caterpillars. This plant is often considered a wildflower and can spread quickly, making it an excellent addition to a meadow or less manicured area of your garden. If you let Queen Anne’s Lace grow in a designated spot, it will attract both adult butterflies and caterpillars.
Carrot (Daucus carota)
Although primarily grown for its roots, the carrot plant also serves as a host for Black Swallowtail caterpillars. The plant’s feathery, aromatic leaves are particularly attractive to caterpillars, especially those looking for a tender, flavorful meal. If you grow carrots in your garden, you may notice caterpillars feeding on the foliage. Consider leaving a few plants to flower, as the seeds and flowers will also attract beneficial insects.
Celery (Apium graveolens)
Celery, often associated with its crisp stalks, also serves as a host plant for Black Swallowtail caterpillars. Like parsley and dill, the leaves of celery are tender and flavorful, making them an ideal food source. Growing celery in your garden is an excellent way to provide nourishment for these caterpillars while also harvesting stalks for your own culinary use.
Lesser-Known Host Plants
Rue (Ruta graveolens)
Rue, an herb with a distinctive, bitter aroma, is another host plant for Black Swallowtail caterpillars. This plant is often used as an ornamental or for medicinal purposes, but its bitter taste makes it less appealing to other herbivores. The caterpillars, however, are not deterred by the flavor and will readily feed on its leaves. If you want to support Black Swallowtails, consider adding rue to your garden.
Spicebush (Lindera benzoin)
Spicebush, a shrub with aromatic leaves and small, fragrant flowers, is another host plant used by the Black Swallowtail caterpillar. This plant is native to parts of North America and can be planted to attract both caterpillars and adult butterflies. Spicebush is particularly beneficial in shaded garden areas, where its dense foliage provides a safe and hidden place for the caterpillars to feed and grow.
Wild Carrot (Daucus carota)
Wild carrot, also known as Queen Anne’s Lace in its wild form, is a favorite for Black Swallowtail caterpillars. It is similar to the domesticated carrot, but it has a more delicate structure and is often found in meadows, roadsides, and fields. Wild carrot is an excellent addition to any wildflower garden, as it attracts not only caterpillars but also a variety of pollinators.
How to Attract Black Swallowtail Caterpillars to Your Garden
Planting Host Plants
The easiest way to attract Black Swallowtail caterpillars to your garden is to plant their host plants. Parsley, dill, fennel, Queen Anne’s Lace, and carrots are all great options. You can grow these plants in a vegetable garden, herb garden, or designated butterfly garden. Planting these species in clusters will make your garden more appealing to the butterflies.
Avoid Pesticides
If you want to attract Black Swallowtail caterpillars, it’s essential to avoid using harmful pesticides in your garden. Caterpillars are particularly sensitive to chemicals, and pesticides can kill them or harm their development. Opt for organic or natural pest control methods that are safe for beneficial insects.
Providing Shelter
Black Swallowtail caterpillars need shelter from predators and extreme weather. Consider planting a variety of shrubs, tall plants, and grasses to provide a safe haven for them to feed and pupate. Providing areas of shade and protection will encourage these caterpillars to thrive in your garden.
Planting for All Stages
To support Black Swallowtail butterflies throughout their life cycle, consider planting both host plants and nectar plants. As caterpillars feed on the host plants, the adult butterflies will feed on nectar from plants like milkweed, lantana, or zinnias. This approach will ensure your garden is attractive to both caterpillars and adult butterflies.
Benefits of Supporting Black Swallowtail Caterpillars
Supporting Biodiversity
By growing host plants for Black Swallowtail caterpillars, you’re helping to support biodiversity in your garden. These caterpillars are part of a larger ecosystem that includes other insects, birds, and pollinators. By attracting them to your garden, you’re contributing to the health and stability of the local ecosystem.
Educational Opportunities
Supporting Black Swallowtail caterpillars in your garden provides valuable educational opportunities, especially for children. Observing the caterpillar’s life cycle, from egg to caterpillar to butterfly, is a fascinating and rewarding experience. It can help foster an appreciation for nature and teach important lessons about conservation.
Aesthetic Appeal
In addition to supporting the lifecycle of these beautiful butterflies, planting their host plants can add aesthetic value to your garden. Many of these plants, such as parsley, dill, fennel, and Queen Anne’s Lace, are lovely additions to a garden, offering both beauty and function. The presence of Black Swallowtail butterflies in your garden adds an extra layer of charm.
Conclusion
By planting the right host plants, such as parsley, dill, fennel, and Queen Anne’s Lace, you can provide Black Swallowtail caterpillars with the resources they need to thrive. These plants not only support caterpillars but also attract adult butterflies and other pollinators, benefiting the entire garden ecosystem. Avoiding pesticides and providing shelter for the caterpillars will ensure a safe and nurturing environment for these insects. Gardening for Black Swallowtail caterpillars is not only an act of conservation but also a way to enhance the beauty and biodiversity of your garden.
