Black Swallowtail Host Plants: Essential Guide for Gardeners

Black swallowtail butterflies are colorful and graceful creatures, often seen in open areas like fields, meadows, and parks.

One key aspect of their life cycle involves finding suitable host plants, which provide essential sustenance for their eggs and caterpillars. In this article, we’ll explore everything you need to know about black swallowtail host plants.

 
Black Swallowtail Host Plants
Black Swallowtail

These butterflies, known scientifically as Papilio polyxenes, have specific plant preferences, mainly gravitating to the parsley family (Apiaceae). These include common plants such as carrots, celery, dill, and Queen Anne’s lace.

When planning your garden, including some of these host plants can attract these beautiful creatures and promote their life cycle.

While these host plants serve as nurseries for the swallowtail caterpillars, it is also essential to be mindful of potential downsides.

First, consider that these caterpillars feed on these plants, which could affect your garden’s overall aesthetics. Second, avoid using insecticides, as they can harm the delicate butterflies and their offspring.

Black Swallowtail: An Overview

Life Cycle

The life cycle of a black swallowtail (Papilio polyxenes) consists of four stages: egg, larva, pupa, and adult. The female lays pale yellow eggs on host plants.

Young larvae are mostly black with a white saddle, while older larvae have green and black bands.

Habitat and Geographic Range

Black swallowtails inhabit open areas like fields, meadows, parks, and wetlands. They are commonly found in sunny backyards across North and Central America.

Distinctive Markings

Black swallowtails have predominantly black wings with yellow, blue, orange, and red markings. Males feature a more noticeable yellow band, while females exhibit larger size and wingspan.

Comparing Swallowtail Species

There are several swallowtail species, including:

  • Eastern tiger swallowtail
  • Giant swallowtail
  • Pipevine swallowtail
  • Zebra swallowtail
  • Spicebush swallowtail

Swallowtail Comparison Table

SpeciesWingspanHabitatMarkings
Eastern tiger3.1 – 5.5 inches (8 – 14 cm)Forests, meadows, gardensYellow with black tiger-like stripes
Giant swallowtail4.5 – 6.7 inches (11 – 17 cm)Tropical, subtropical areasDark brown with yellow bands and spots
Pipevine swallowtail2.8 – 5.1 inches (7 – 13 cm)Woodlands, meadowsIridescent blue with white spots
Zebra swallowtail2.75 – 4 inches (7 – 10 cm)Wet areas, woodlandsWhite with black stripes
Spicebush swallowtail3.5 – 4.5 inches (9 – 11 cm)Forests, woodlandsBlue and black upper wings, two orange eyespots

Black Swallowtail Host Plants

Common Host Plants

Here are some common host plants for the black swallowtail:

  • Fennel (Foeniculum vulgare): A popular herb with a mild, licorice-like flavor used in cooking
  • Dill (Anethum graveolens): A fragrant herb often used in pickling and as a seasoning
  • Parsley (Petroselinum crispum): A widely cultivated biennial herb, often used as a garnish
  • Carrot (Daucus carota): A root vegetable, nutritious and versatile in cooking
  • Celery (Apium graveolens): A crisp, watery vegetable often used in salads and cooking
  • Queen Anne’s Lace (Daucus carota): A wildflower, also known as wild carrot, that’s native to Europe

Uncommon Host Plants

Some less common host plants include:

  • Rue (Ruta graveolens): A plant from the Rutaceae family with strong-smelling leaves
  • Golden Alexander (Zizia aurea): A perennial native to North America, with small yellow flowers
  • Ash (Fraxinus spp.): A group of medium to large trees, in the olive and lilac family

Planting Tips for Optimal Growth

Here are some tips for planting and maintaining a healthy host plant garden for black swallowtails:

  1. Plant a variety of common and uncommon host plants to attract a diverse population of black swallowtails and other butterflies.
  2. Choose a sunny location with protection from wind for optimal growth of the host plants and to provide a welcoming habitat for the butterflies.
  3. Provide a water source for the butterflies, such as a shallow container filled with water and pebbles for landing spots.
  4. Allow the caterpillars to consume some of the host plants, as this is part of their life cycle. Don’t worry, they won’t eat it all!
  5. Avoid using insecticides in the garden, as this can harm the caterpillars and other pollinators.
Host PlantGrowth RequirementsSpecial Notes
Fennel, Dill, ParsleyFull sun, well-drained soilAnnual herbs; plant in spring
Carrot, CeleryFull sun, moist soilVegetables; grow from seeds or transplant
Queen Anne’s LaceFull sun, well-drained soilHardy wildflower; requires little care
Rue, Golden AlexanderFull sun, well-drained soilPerennial plants; need regular pruning
AshFull sun, moist, well-drained soilTrees; grow from seeds or saplings

By selecting a diverse range of host plants, planting them properly, creating a welcoming environment, and avoiding insecticides, your backyard can be a thriving and supportive habitat for black swallowtail butterflies.

Caterpillar to Butterfly Transformation

Feeding and Growth

Black swallowtail caterpillars feed on plants from the carrot family (Apiaceae) such as parsley, dill, and fennel.

They hatch from eggs and progress through five growth stages, or instars, as they consume leaves and flowers1. Here are some key characteristics of the caterpillars:

  • Green with narrow black bands
  • Interrupted by yellow-orange dots
  • Can reach 2 inches in length

Pupation and Chrysalis

After completing five instars, caterpillars pupate and form a chrysalis. This stage lasts about two weeks, during which they undergo a significant transformation.

An adult butterfly eventually emerges from the chrysalis, ready to mate and lay eggs.

Overwintering

Some black swallowtail caterpillars overwinter as pupae. They wait until the warmer months to emerge as butterflies. This strategy helps them survive cold temperatures and a lack of available host plants during winter.

Parasitic Threats

Black swallowtail caterpillars face threats from parasitic wasps, which lay their eggs inside the caterpillars. When the wasp larvae hatch, they consume the caterpillar from the inside, ultimately causing its death.

To deter these threats, black swallowtail caterpillars can extend a forked, fleshy organ called the osmeterium, which emits a foul-smelling defensive secretion.

Comparison of Black Swallowtail Life Stages:

Life StageDurationActivity
Egg10 daysDevelop into caterpillars
Caterpillar3 to 4 weeksFeed and grow through five instars
Pupa (Chrysalis)2 weeksTransform into adult butterflies
Adult Butterfly1 to 2 weeks2Mate and lay eggs on host plants, and feed on nectar from flowers

Attracting Black Swallowtails to Your Garden

Nectar Plant Recommendations

Black Swallowtails are partial to colorful, sweet nectar plants. A variety of flowers can provide nectar to attract these beautiful butterflies:

  • Zinnias are a favorite for their bold colors and easy growth.
  • Milkweed draws Black Swallowtails with its fragrant nectar.
  • Coneflowers offer many benefits, including purple coneflowers and butterfly weed.
  • Joe Pye Weed provides height and charisma to your butterfly garden.
  • Phlox entices Swallowtails with fragrance and abundant nectar.
  • Clover is a low-maintenance, petite nectar source.
  • Thistles provide nectar and nesting material for diverse pollinators.

Creating a Butterfly-Friendly Habitat

A balanced habitat is essential for a thriving butterfly garden. Here are a few elements to consider:

  • Host plants: Black Swallowtails lay eggs on plants from the parsley family, such as parsley (Petroselinum crispum), dill, and Queen Anne’s lace.
  • Nectar plants: Provide a diverse selection of nectar-producing flowers mentioned above.
  • Watering: Keep your garden hydrated but avoid overwatering to prevent damping off of host plants.
  • Shade: A mix of sunny spots and partial shade is ideal for butterflies to thermoregulate their body temperature.

Watering and Shade

Proper watering is essential to keeping your butterfly garden healthy, while providing shade gives butterflies the option to rest or cool off:

  • Water your garden evenly and regularly. Avoid soaking or overwatering.
  • Create shade spots by planting taller plants next to shorter ones, or by adding structures, like a trellis or pergola.

Seasonal Considerations

As seasons change, different host and nectar plants become relevant. Consider planting a mix of annuals and perennials to cover multiple seasons:

Spring PlantsSummer PlantsFall Plants
MilkweedZinniaBee Balm
CloverConeflowerJoe Pye Weed
ThistlesPhloxAsters

Incorporating plants for each season ensures a colorful, lively butterfly garden throughout the year.

Conservation and Importance

Black Swallowtail’s Role in Ecosystem

The Black Swallowtail (Papilio polyxenes) is a butterfly species found in various habitats such as fields, meadows, parks, wetlands, and prairies, spanning from southern Canada to northern Mexico.

These butterflies play a vital role in pollination, which benefits various plant species in their ecosystem.

They depend on host plants like wild carrot, poison hemlock, water hemlock, and Foeniculum vulgare to lay their eggs and provide food for their caterpillars.

Threats and Conservation Efforts

Black Swallowtails face multiple challenges, such as habitat loss, pesticide exposure, and climate change.

Here are some common host plants for black swallowtails and their caterpillars:

  • Trees: Black Cherry, Magnolia, Wild Lime
  • Shrubs: Hoptree, Hercules Club
  • Herbs: Citrus, Pawpaw, Wild Carrot, Poison Hemlock, Water Hemlock

To conserve and encourage black swallowtail populations, consider the following actions:

  • Plant a variety of host plants in your garden for their larvae, such as dill, parsley, or fennel
  • Provide nectar-rich flowers to supply food for adult butterflies
  • Refrain from using pesticides in your garden
  • Conserve the natural habitat of these butterflies by supporting local biodiversity efforts

Conclusion

In conclusion, the Black Swallowtail butterfly, scientifically known as Papilio polyxenes, has a deep connection with specific host plants, primarily from the parsley family (Apiaceae).

These plants, including carrots, celery, dill, and Queen Anne’s lace, are essential for the butterfly’s life cycle, providing sustenance for their eggs and caterpillars.

Gardeners looking to attract these graceful creatures should incorporate these plants, but be prepared for caterpillars to feed on them. Additionally, it’s crucial to avoid pesticides, which can harm these delicate beings.

By understanding their preferences and needs, one can create a thriving habitat for Black Swallowtails, promoting biodiversity and the beauty of nature.

Footnotes

  1. https://arthropod.uark.edu/black-swallowtail-caterpillar-parsleyworm/

  2. https://putnam.cce.cornell.edu/resources/meet-the-pollinators-the-swallowtail-butterfly

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Black Swallowtail, newly hatched

Chrysalis on fennel plant
This morning, as I was leaving for work, I noticed a new arrival. I guess this answers my question of “How long til it hatches?” Enjoy the pictures.
Ken

Hi Ken,
Thanks for the follow-up. This is a Black Swallowtail as we suspected.

Letter 2 – Black Swallowtail Metamorphosis

he

Butterfly
Location:  Bellville, Ohio
August 3, 2010 6:26 pm
I thought you might like these pictures of A Black Swallowtail, from start to finish.
Thanks
Jim

Black Swallowtail Caterpillar

Hi Jim,
Thanks for sending us your wonderful documentation of the metamorphosis of a Black Swallowtail.  Maria Sibylla Merian would be impressed.  It appears as though the Chrysalis image is of the exuvia, the cast off skin after the butterfly has emerged. 

It is also quite curious that the Chrysalis is up-side-down.  Generally the Swallowtail Butterflies make a Chrysalis that is upright and supported by the silk girdle.

The adult imago is a female.  The female has blue markings while the male has yellow spots.

Letter 3 – Black Swallowtails Emerge

Subject: The eastern Swallotails are emerging
Location: Omaha, NE
August 16, 2013 6:00 pm
Last month you identified my butterfly as an eastern swallowtail. Well, they defoliated my curled parsley, and went through three bunches of organic curled parsley from the store before they settled down to pupating, but they’re all emerging now! Here are the pics of some of them as they emerged and got ready to fly
Signature: lyredragon

Black Swallowtail
Black Swallowtail

Dear lyredragon,
We actually identified your butterfly as a Black Swallowtail six weeks ago.  Thanks for sending us these new images of a second generation of Black Swallowtails that will be filling the skies of Omaha. 

We saw a few Black Swallowtails on our recent visit to Ohio, and we also spied a Spicebrush Swallowtail  We did manage to photograph an elusive Eastern Tiger Swallowtail nectaring on some Joe Pye Weed in a field in western Pennsylvania, and we will post those photos when we have some time.

Black Swallowtail
Black Swallowtail

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    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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2 thoughts on “Black Swallowtail Host Plants: Essential Guide for Gardeners”

  1. Sorry, I accidentally omitted the “black” part of their name. anyway, we had 21 caterpillars at the highest count by the time all of the eggs hatched, but only 15 caterpillars pupated. Most of them so far are coming out female.

    Reply

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