Why Host Plants Matter
A butterfly garden isn't just about nectar plants for adults — it must also include host plants where females lay their eggs and caterpillars feed. Without the right host plants, swallowtail butterflies cannot complete their life cycle in your garden. The good news is that many swallowtail host plants are beautiful, useful, or easy to grow, making them excellent additions to any landscape.
North American Swallowtail Species & Their Host Plants
1. Black Swallowtail (Papilio polyxenes)
The black swallowtail is the swallowtail most likely to visit kitchen gardens. Its caterpillars feed on plants in the carrot family (Apiaceae), including:
- Dill (Anethum graveolens) — A top choice; caterpillars love it.
- Parsley (Petroselinum crispum) — Flat-leaf parsley is especially popular.
- Fennel (Foeniculum vulgare) — Bronze fennel is both ornamental and functional.
- Queen Anne's Lace (Daucus carota) — A wildflower that's a natural host.
- Carrot tops — Garden carrots can double as host plants.
Tip: Plant extra dill and parsley if you want both herbs for cooking and caterpillar food — they are surprisingly voracious in later instars.
2. Eastern Tiger Swallowtail (Papilio glaucus)
One of North America's largest and most spectacular butterflies, the tiger swallowtail uses tree leaves as its primary host plants:
- Wild Cherry / Black Cherry (Prunus serotina)
- Tulip Poplar (Liriodendron tulipifera)
- Sweet Bay Magnolia (Magnolia virginiana)
- Ash trees (Fraxinus species)
- Cottonwood (Populus species)
If you have mature trees of these species on your property, tiger swallowtails may already be using them.
3. Spicebush Swallowtail (Papilio troilus)
This stunning dark swallowtail has a narrower host plant range, primarily using:
- Spicebush (Lindera benzoin) — The #1 host plant; a beautiful native shrub with fragrant yellow flowers in spring and bright red berries in autumn.
- Sassafras (Sassafras albidum) — A native tree with aromatic leaves and interesting mitten-shaped foliage.
Spicebush caterpillars are especially remarkable — they fold leaves to create shelters and have large false eyespots that mimic a snake's head to deter predators.
4. Giant Swallowtail (Papilio cresphontes)
North America's largest butterfly, the giant swallowtail, lays eggs on plants in the citrus family (Rutaceae):
- Common Hoptree (Ptelea trifoliata)
- Citrus trees (orange, lemon, lime) — where it's called the "orange dog"
- Prickly Ash (Zanthoxylum americanum)
- Rue (Ruta graveolens) — A garden herb that doubles as a host plant
How to Design a Swallowtail-Friendly Garden
| Swallowtail Species | Best Host Plants to Grow | Ease of Growing |
|---|---|---|
| Black Swallowtail | Dill, Parsley, Fennel | Easy (annual herbs) |
| Tiger Swallowtail | Wild Cherry, Tulip Poplar | Moderate (trees) |
| Spicebush Swallowtail | Spicebush, Sassafras | Easy (native shrubs/trees) |
| Giant Swallowtail | Rue, Hoptree | Easy (small plants) |
Key Tips for Success
- Avoid pesticides — even "organic" options can harm caterpillars. If you must treat a pest problem elsewhere in the garden, do so carefully and away from host plants.
- Plant in clusters — groups of host plants are easier for butterflies to find and provide more food for caterpillars.
- Embrace the damage — chewed leaves mean caterpillars are thriving. Healthy host plants can support multiple caterpillars without permanent harm.
- Include nectar plants nearby — adult butterflies need flowers too. Combine host plants with nectar sources like coneflowers, zinnias, and lantana.