Spicebush Swallowtail Host Plants: What to Grow
If you want spicebush swallowtails in your garden, there’s one thing you need: the right plants. This species doesn’t do well with substitutes. The females are selective about where they lay eggs, and the caterpillars can only complete development on a specific group of native shrubs and trees. Get the plants right and the butterflies tend to show up on their own.
The primary host plants are spicebush (Lindera benzoin), sassafras (Sassafras albidum), and, to a lesser extent, tulip tree (Liriodendron tulipifera) and sweetbay magnolia (Magnolia virginiana). All of these are native to eastern North America and grow well across a range of yard conditions, particularly in sites with partial shade and reasonable moisture.
Spicebush: The Best Choice for Most Gardens
Lindera benzoin is the gold standard for attracting spicebush swallowtails. The common name of the butterfly comes directly from this shrub, which tells you something about how closely the two are associated. Female butterflies spend time searching spicebush leaves, drumming them with their forelegs to detect the chemical compounds that signal a suitable egg-laying site.
Spicebush is a versatile native shrub that tolerates conditions many garden plants won’t. It grows well in partial to full shade, which makes it genuinely useful in the woodland margins and shaded borders where many gardeners struggle to find plants that perform. It prefers moist, well-drained soil but handles periodic wet conditions better than most shrubs. Mature plants reach six to twelve feet in height.
Beyond butterfly hosting, spicebush earns its place in a native garden independently. It produces small yellow flowers very early in spring, often before leaves emerge, making it one of the first nectar sources of the season. In fall, it blazes yellow and produces glossy red drupes that birds eat eagerly. Planting it is genuinely a multi-benefit decision rather than a single-purpose one.
Sassafras: A Larger Option with Multiple Benefits
Sassafras albidum is a native tree that grows across the eastern US and into the Midwest. It can reach 30 to 60 feet at maturity, though in open conditions it often stays smaller and spreads through root suckers to form thickets. This suckering habit makes it a good candidate for a naturalized edge or woodland area where you’re not managing for a tidy, single-stem specimen.
The leaves are highly variable, producing three distinct shapes on the same tree: unlobed, mitten-shaped with one lobe, and three-lobed. This variability makes it easy to identify once you know what to look for. Spicebush swallowtail caterpillars use all leaf types without any apparent preference, so the shape variation isn’t a concern for hosting success.
Sassafras grows in full sun to partial shade and tolerates a range of soil conditions, including dry, sandy soils where spicebush would struggle. This makes it a better choice for drier sites or for a taller host plant option in a sunny border. Fall color is spectacular, ranging from yellow through orange and red, and the tree hosts a wide range of other insects beyond spicebush swallowtails.
Tulip Tree and Sweetbay Magnolia as Secondary Hosts
Liriodendron tulipifera (tulip tree or tulip poplar) serves as a secondary host plant in some parts of the spicebush swallowtail’s range. It’s a large, fast-growing canopy tree that reaches impressive heights and is native across much of the eastern US. Caterpillars found on tulip tree tend to be more common at the northern edge of the spicebush swallowtail’s range where spicebush is less abundant.
Magnolia virginiana (sweetbay magnolia) is used sporadically, primarily in the southeastern portion of the range. It’s a semi-evergreen to evergreen shrub or small tree that grows in wet, acidic soils near swamps and stream edges. If you have a wet area in your yard that other plants won’t tolerate, sweetbay magnolia is worth considering both as a host plant and as an ornamental.
Neither tulip tree nor sweetbay magnolia is as reliable for attracting egg-laying females as spicebush and sassafras. If your primary goal is supporting this butterfly species, start with spicebush and sassafras. The secondary hosts are good additions to a diverse native planting but shouldn’t be the foundation of a spicebush swallowtail habitat plan.
The caterpillar host plants guide for gardeners covers host plant relationships for many butterfly and moth species, including comparisons of how different plants rate for specific species.
Planting for Success
Spicebush is dioecious, meaning male and female plants are separate individuals. Only female plants produce the berries, but both sexes serve equally well as caterpillar host plants. When buying, try to get at least two plants to ensure genetic diversity and, if fruiting is a goal, confirm you have both sexes. Many native plant nurseries sell rooted cuttings of known sex.
Plant in fall or early spring when soil temperatures favor establishment root growth. Dig a hole two to three times the width of the root ball but no deeper than it. Water thoroughly at planting and during dry spells in the first growing season. Once spicebush is established, it’s quite drought-tolerant despite its preference for moist conditions, and it rarely needs supplemental watering.
Grouping multiple spicebush plants together rather than planting a single individual provides more food surface and increases the likelihood that roving females detect the plant chemical signals. A cluster of three or more in a partially shaded area will attract significantly more egg-laying activity than a lone specimen in an otherwise open sunny bed.
Understanding the Caterpillar’s Leaf Rolling Behavior
Spicebush swallowtail caterpillars have a distinctive behavior of folding a leaf over themselves and securing it with silk to create a shelter. Early instars make small rolls from portions of a leaf. Later instars create larger folds using the entire leaf. You’ll notice these rolled-leaf shelters on your spicebush plants, and finding them is a good sign that the species has found your planting.
The caterpillar emerges from its shelter to feed, usually at night, and returns to rest during the day. The shelter provides protection from some visual predators and regulates microclimate to some degree. If you open one of these shelters out of curiosity, the caterpillar inside will likely drop and curl into a defensive posture. They’re harmless but startled easily.
For species identification and life cycle information across swallowtail butterflies, the swallowtail species identification guide includes detailed descriptions of each stage for spicebush and related species.
Key Takeaways
- Spicebush (Lindera benzoin) is the most reliable host plant for attracting spicebush swallowtail egg-laying. Plant in partial shade with moist, well-drained soil.
- Sassafras is an excellent alternative for drier, sunnier sites or where a larger tree is appropriate. Its drought tolerance makes it useful where spicebush would struggle.
- Plant spicebush in groups of three or more to maximize chemical signal detection by roving females looking for egg-laying sites.
- Look for rolled leaves on your host plants as evidence of caterpillar presence. The rolls are shelters the caterpillars construct using silk to fold the leaf over themselves.
Frequently Asked Questions
How long does spicebush take to grow large enough to support caterpillars?
A one-gallon container plant can begin supporting a few caterpillars in its first or second year. Early instars eat less and cause less damage, so even a young plant can host them without major setback. By the third or fourth year, a well-watered spicebush typically has enough leaf mass to support a full cohort of caterpillars through completion without significant defoliation damage to the plant.
Will spicebush swallowtails find my plants on their own?
Yes, if spicebush swallowtails are present in your area. Females actively search for host plant chemical signals during their breeding flights. If you’re within their range (most of eastern North America east of the Great Plains), planting spicebush or sassafras in a garden with some open space for flight access will typically attract egg-laying females within a season or two. Urban gardens may take a bit longer to be discovered.
Do spicebush swallowtail caterpillars damage the host plants?
They can cause noticeable defoliation, especially on smaller plants when a large group is present. However, established spicebush and sassafras plants recover quickly from even heavy feeding pressure. Think of caterpillar damage as a temporary setback rather than a permanent problem. Plants that are regularly browsed by caterpillars often push new growth vigorously after defoliation if they’re well-established and watered.
Can I grow spicebush in full sun?
Spicebush tolerates full sun reasonably well if moisture is consistent, but it genuinely prefers partial shade. In full sun with dry soil, it tends to look stressed by midsummer, with scorched leaf edges and reduced vigor. If your available planting spots are mostly sunny, sassafras is a better primary host option. It handles drier, sunnier conditions significantly better than spicebush.
Are there non-native plants that spicebush swallowtails will use as hosts?
Occasionally, spicebush swallowtail caterpillars have been found on non-native Lindera species sold as ornamentals, including Lindera obtusiloba. However, success rates on non-native relatives are less consistent, and some species in the same family may not trigger egg-laying behavior reliably. Native spicebush and sassafras remain the recommended choices, and they’re widely available from native plant nurseries across most of their range.
