Black Swallowtail: All You Need to Know for Butterfly Enthusiasts

The black swallowtail butterfly, scientifically known as Papilio polyxenes, is a beautiful and intriguing species found in various habitats.

They are often seen in open areas such as fields, meadows, parks, and wetlands, making them a lovely sight in sunny backyards or during outdoor adventures.

Males and females of this species display unique wing patterns which can help in telling them apart.

Male black swallowtails usually have more noticeable yellow and less blue on the wings, while females tend to be larger and exhibit a wingspan of 3¼ to 4¼ inches.

Both genders showcase stunning colors on their wings, including a mix of black, yellow, blue, orange, and red, making them an eye-catching sight in nature.

As you learn more about the black swallowtail, you’ll discover fascinating facts about its life cycle, role in the ecosystem, and the significance of its vibrant wing patterns.

Knowing more about these captivating creatures can deepen your appreciation for the natural world and enhance your experience when encountering them in the wild.

Black Swallowtail Overview

Identification and Physical Description

The black swallowtail, also known as Papilio polyxenes, is a large, black butterfly with a wingspan of 2½ – 3½ inches (6.7 – 8.9 cm).

It is characterized by its distinctive tails and colorful markings on the wings. Some key features include:

  • Black wings with yellow, blue, orange, and red markings
  • Noticeable tails on the hindwings

Male Black Swallowtail vs Female Black Swallowtail

Male and female black swallowtails have some differences in their appearance:

FeatureMale Black SwallowtailFemale Black Swallowtail
Yellow markings on wingsMore noticeableLess noticeable
Blue markings on wingsLess extensiveMore extensive
SizeSmallerLarger, with a wingspan of 3¼ to 4¼ inches

Habitat and Distribution

Black swallowtails are commonly found in North America, particularly in Eastern parts of the continent. They prefer open areas with abundant sunlight, and can be found in various habitats:

  • Fields
  • Meadows
  • Parks
  • Wetlands
  • Prairies
  • Sunny backyards

In addition, the black swallowtail is the state butterfly of Oklahoma.

Life Cycle and Development

Eggs and Egg Stage

  • The black swallowtail starts life as pale yellow eggs.
  • Eggs can be found laid singly on host leaves or flowers.

When the eggs of the black swallowtail butterfly are laid, they are pale yellow in appearance and are placed individually on host leaves or flowers.

Caterpillars and Larval Stage

  • Caterpillars are green with black bands.
  • Each black band contains yellow-orange spots.
  • Known as parsleyworms.

The larval stage of the black swallowtail, also referred to as parsleyworms, features green caterpillars adorned with black bands on each segment, which are interrupted by yellow-orange dots.

 

Black Swallowtail Caterpillar

Chrysalis and Pupal Stage

  • Chrysalis can be brown with dark striations or green.
  • Represents the butterfly’s transformation stage.

During the pupal stage, the black swallowtail caterpillar forms a chrysalis, which can be either brown with dark striations or green. This stage represents the transformation from caterpillar to adult butterfly.

Black Swallowtail Emerges from Chrysalis

Adult Butterfly Stage

  • Wingspan: 2½ – 3½ inches (6.7 – 8.9 cm).
  • Large black butterflies with tails.
  • Males have a band of bright yellow spots on their upper wings.
  • Females may lack or display heavy yellow bands.
  • Number of generations: 3 or more per year.

In the adult butterfly stage, the black swallowtails have a wingspan of 2½ to 3½ inches (6.7 – 8.9 cm) and are large black butterflies with tails.

Males feature a band of bright yellow spots on their upper wings, while females may lack the heavy yellow bands or display them only partially. The black swallowtail produces 3 or more generations per year.

Host Plants and Nectar Sources

Preferred Host Plants

Black Swallowtail caterpillars primarily feed on plants from the Apiaceae family. Some common plants include:

  • Dill: a popular herb with feathery leaves, often found in gardens
  • Parsley: another common herb, characterized by its curly or flat leaves
  • Fennel: a perennial herb with a sweet licorice flavor, used in cooking and herbal remedies
  • Carrot: the caterpillars may feed on the leaves of this root vegetable
  • Queen Anne’s Lace: also known as wild carrot, this plant features delicate white flowers
  • Parsnip: a root vegetable closely related to carrots, with large, green leaves
  • Rue: an evergreen shrub with yellow flowers, sometimes used in traditional medicine
  • Celery: a vegetable with long, fibrous stalks, often used in salads and other dishes

It’s important to note that caterpillars do not strictly feed on these plants only and may choose other plants within their natural habitats.

Attractive Nectar Plants

In order to create a welcoming environment for Black Swallowtail butterflies, consider planting nectar sources they are attracted to. Examples include:

  • Milkweed: a plant with clusters of small, pink flowers, known for its importance to Monarch butterflies as well
  • Thistle: a group of flowering plants with spiky flower heads, often found in meadows and fields
  • Zinnias: brightly colored annual flowers that add a pop of color to any garden
  • Clover: both red and white clover can offer nectar for butterflies and are often found in lawns and meadows
  • Red Clover: characterized by its round, pink flowers, this plant is a nitrogen fixer and benefits soil health
PlantHost PlantNectar Source
Dill✔️ 
Parsley✔️ 
Fennel✔️ 
Carrot✔️ 
Queen Anne’s Lace✔️ 
Parsnip✔️ 
Rue✔️ 
Celery✔️ 
Milkweed ✔️
Thistle ✔️
Zinnias ✔️
Clover (red & white) ✔️

By incorporating both host and nectar plants in your butterfly garden, you are sure to provide a nurturing environment for Black Swallowtail butterflies throughout their life stages.

Gardening Considerations

Encouraging Black Swallowtail Populations

Managing The Swallowtail Caterpillar As A Pest

  • Handpick caterpillars: If you find caterpillars on your herbs, simply remove them by hand.
  • Natural predators: Encourage natural enemies like birds and insects through habitat provisioning.
  • Avoid pesticides: Most pesticides can be harmful to beneficial insects like monarchs and the American swallowtail.

Parsley Worm

Black Swallowtail Butterfly Gardening Tips

  • Create a diverse garden: Plant a variety of flowering plants that bloom at different times to provide continuous nectar sources for black swallowtails.
  • Provide shelter: Offer places for overwintering, such as shrubs, leaf piles, or dead branches.

Comparison Table: American Swallowtail vs Black Swallowtail

FeatureAmerican SwallowtailBlack Swallowtail
SizeLargerSmaller
ColorYellow with black stripesBlack with yellow patterns
Host PlantsLeaves of trees and shrubsHerbs, such as parsley and dill

Pros of encouraging black swallowtail populations:

  • They act as pollinators, benefiting plants in the garden.
  • Observing the butterflies can be enjoyable and educational for both children and adults.
  • They contribute to a healthy ecosystem by providing a food source for other animals.

Cons of encouraging black swallowtail populations:

To encourage a healthy black swallowtail population in your garden while minimizing potential issues with their caterpillars, it’s important to create an environment that supports their entire life cycle.

By providing a diverse selection of nectar sources and host plants, you can enjoy the beauty of these butterflies while they contribute to a thriving garden ecosystem.

Black Swallowtail

Defense Mechanisms and Threats

Osmeterium and Predators

Black swallowtail caterpillars possess a unique defense mechanism called the osmeterium. The osmeterium is a forked, horn-like organ located behind the caterpillar’s head.

When threatened, the caterpillar can evert this organ and emit an unpleasant odor to deter predators1.

Common predators of black swallowtail caterpillars and butterflies include:

  • Wasps
  • Spiders
  • Birds

Mimicry

Black swallowtails exhibit a special type of camouflage called Batesian mimicry. Their hindwings’ color patterns resemble those of the toxic Pipevine Swallowtail (Battus philenor)2.

Here are some distinguishing features between Black Swallowtail and Pipevine Swallowtail:

  • Black Swallowtail: Yellow spots on wings, lacks iridescence
  • Pipevine Swallowtail: Iridescent blue, lacks prominent yellow spots

By mimicking the appearance of a toxic butterfly, the black swallowtail gains protection from predators that may avoid consuming the noxious species.

Challenges Faced By Black Swallowtails

Black Swallowtails face a few challenges which include:

  • Habitat loss and fragmentation
  • Pesticide exposure
  • Competition with other butterfly species

Despite these challenges, black swallowtails remain relatively successful and adaptive, with populations flourishing across much of their range.

Additional Interesting Facts

Relation to Other Swallowtail Species

Black swallowtails (Papilio polyxenes) are closely related to other swallowtail butterfly species, and can sometimes be confused with them. To differentiate, observe the following comparison4:

SpeciesHindwing – From BelowHindwing – From Above
Black SwallowtailTwo rows of red-orange spotsTwo rows of yellow spots
Pipevine SwallowtailOne row of light blue spotsDark, iridescent-blue field
Eastern TigerDark blue spots with tinges of yellowRow of large, light-colored spots

In terms of habitat, black swallowtails are often found in open areas such as fields, meadows, parks, wetlands, and prairies1.

These attractive butterflies are also known to visit gardens, where they are drawn to nectar-rich flowers like phlox and winters5.

Conclusion

The Black Swallowtail, scientifically termed Papilio polyxenes, is a captivating butterfly native to North America. Distinguished by its vibrant wing patterns, its life cycle spans from pale yellow eggs to striking adult butterflies.

Thriving in open habitats, they feed on plants like dill and parsley during their caterpillar stage and are drawn to nectar-rich flowers as adults.

Their unique defense mechanisms, such as the osmeterium and Batesian mimicry, showcase nature’s intricate adaptations.

Footnotes

  1. https://www.si.edu/object/black-swallowtail-caterpillar-defense-mechanism:yt_NTVdgzOwyrM 2 3

  2. https://entnemdept.ufl.edu/creatures/bfly/bfly2/eastern_black_swallowtail.htm

  3. https://alabama.butterflyatlas.usf.edu/species/details/106/black-swallowtail 2 3

  4. https://mdc.mo.gov/discover-nature/field-guide/black-swallowtail-parsnip-swallowtail

  5. https://mastergardener.extension.wisc.edu/files/2015/12/BlackSwallowtail.pdf

Reader Emails

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

Letter 1 – Black Swallowtail

Some Kinda Swallowtail
Hi there,
This beauty was on my Chicago area butterfly bush this morning. Do you know which variety this is?
Many thanks,
Joe

Hi Joe,
This is a Black Swallowtail, a female judging by her small yellow spots. This is a common butterfly found in open meadows. The larval food include parsley, carrots, celery and Queen Anne’s Lace.

Letter 2 – Black Swallowtail

Swallowtail
Hi Bugman,
This swallowtail was flying around in my yard this morning and I’m wondering if it’s a black swallowtail.
Joanna

Hi Joanna,
Yes, this is a Black Swallowtail.

Letter 3 – Black Swallowtail

Beautiful Butterfly you might be interested in
Sat, May 16, 2009 at 4:58 AM
I found this guy resting on my azeala bush a few days ago, thought he was beautiful and grabbed my camera. I have never see a butterfly like this in Long Island, NY and possible ideas?
Mary R.
Long Island

Black Swallowtail
Black Swallowtail

Good Morning Mary,
We hated cropping your beautifully composed image of a female Black Swallowtail because it was such a lovely photograph, but our readership is more interested in seeing the insects as large as possible, so we eliminated much of your azalea and the fence in the background. 

Female Black Swallowtails have blue markings on the lower wings while the male has only yellow spots.  The male is also smaller.

Letter 4 – Black Swallowtail

More Black Swallowtail on Long Island, NY
August 22, 2009
Your site was very helpful in identifying a butterfly that has been flying around Bayville NY this summer. I took two more pictures which feel free to add to that section of the site.
This is a female Black Swallowtail flying near a tomato plant, southern exposure. The pictures may not show the yellow spots at the bottom of the tail.
Barry P. from Bayville, N.Y.
Bayville, New York (North Shore of Long Island)

Black Swallowtial
Black Swallowtial

Thanks Barry,
The feeling of movement in your photo is a nice departure from the static images we generally post.

Hi Sirs
Just happened to be on here when your reply came in.
You are very polite about the “feeling of movement”- sorry if it’s a little blurred, but if you are able to use it, feel free. In the past, I have seen Monarch butterflies and sometimes Tiger Swallowtails, but I can’t remember seeing these Black Swallowtails in previous summers.

Usually I see them at the dunes on the beach. Our house is about 100 feet from the beach, so some similarities. I can add that we had torrential rain last night so the plants are very moist. This particular butterfly was exploring (sniffing?) a tomato plant, getting very fragrant about now.

I took the picture to send to my daughter, who is in Southern Florida visiting relatives, possibly going to “Butterfly World” near Fort Lauderdale, hence I came on your site (via Google image search for “butterfly” and “Long Island”) to identify the pix before sending to her.

She is a teenager now, but used to go there when she was much younger, did a project in school re rain forest in first grade, etc so maybe all this will rekindle her interest in butterflies.
Barry D Parker

Letter 5 – Black Swallowtail

black butterfly
Location: Eau Claire, Wis.
July 24, 2011 5:03 pm
I had quite a few minutes in my garden today, July 24, 2011, with this beauty. It was very large as far as butterflies go in West Central Wis. perhaps four or five inches. While it was very interested in my garden it also seemed interested in me and for a while, as I hoped and waited, it seemed it would land on me, circling around.

Flitting from plant to plant, it never stayed long on one. Although it has a ragged wing it seemed to be doing fine. Lovely blue spots one the top of wings with one orange spot each in the center on the inner edge. The undersides, however, have yellow spots.

When it landed it liked to have its wings outstretched. I hope it visits again.
Signature: gail from Wisconsin

Black Swallowtail

Hi Gail,
There are several large dark swallowtail butterflies in your area, and this individual is a female Black Swallowtail,
Papilio polyxenes.  The male does not hae the blue markings on the hind wings which you can see in this photo from our archives.

Letter 6 – Black Swallowtail

Subject: ID of blue butterfly
Location: eastern Ontario – 40km south Ottawa
July 2, 2012 4:16 pm
Your help ID’ing this blue butterfly which was visiting our garden would be much appreciated. About the size of a Monarch.
Signature: Rick

Male Black Swallowtail

Hi Rick,
This is a male Black Swallowtail.  Male Black Swallowtails lack the have more pronounced yellow coloration while female Black Swallowtails have more blue dusting.  The caterpillars are known as carrot worms and they are frequently found on parsley as well.  We just posted a nice series of photos of the Black Swallowtail Caterpillars.

Hi Daniel (Mr. Bugman), thanks so much for your reply.   This is great to know, and we’ll watch for the larval form.    We do have parsley and other some other herbs near the point that photo was taken, perhaps coincidence (and we don’t use chem pesticides).


I had decided that it is really time to start ID’ing the insects that we get, and it is not easy as a neophyte to work successfully through keys.   But a few positive IDs really help, as then I can go backwards through keys with more examples.
Much appreciated.
Rick

Letter 7 – Black Swallowtail

Subject: black with blue spot butterfly
Location: staunton, va
August 31, 2012 5:57 am
Is it a morning cloak?
Signature: MJ

Black Swallowtail

Dear MJ,
The “tails” on the lower wings immediately identify this as one of the Swallowtails.  It is a Black Swallowtail,
Papilio polyxenes, and the dusting of blue on the lower wings identifies this as a female.  She is nectaring on a zinnia, one of the best plant for attracting butterflies and other pollinators to the garden.  Gardeners should plan early if they want zinnias in mid to late summer. 

Zinnias grow easily from seeds that should be started in the early spring or late winter in areas that do not get snow and have hot summers, like the southwest.  The caterpillars of Black Swallowtails are often found feeding on parsley, carrots and other related plants in the vegetable patch.  More information on the Black Swallowtail is available on BugGuide

We have our own theory that the swallowtails that feed most on nectar are the females who need to be strong to survive to lay eggs which are deposited singly on plants rather than in clusters.  We developed this theory because of the reluctance of the Western Tiger Swallowtails at our Mount Washington, Los Angeles offices, to land and visit the flowers. 

We believe them to be “hill topping” males who are hoping to mate with females that are attracted to our own zinnias, lantana and butterfly bush, though the females never seem to be around when we are camera ready.

Letter 8 – Black Swallowtail

Subject: Black Swallowtail Butterfly?
Location: Coryell County, Texas
January 24, 2014 11:20 pm
Hello, I hope you’ve both been well.
I took these photos last February 7, 2013, and I never sent them because I didn’t think the quality of the photos was very sharp. I think I’ve seen Pipevine Swallowtails in our garden before, but I think this may be a Black Swallowtail?

Or a dark phase of a Tiger Swallowtail? They are confusing to me! So lovely, though.
The butterflies like these native plants in the creek bed.
I’ll keep trying to get better photos of the beautiful swallowtails… the quest continues.
Thank you!
I found this reference: https://insects.tamu.edu/fieldguide/cimg266.html
Signature: Ellen

Black Swallowtail
Male Black Swallowtail:  Note orange and black spot on inner margin of hindwings

Hi Ellen,
You are correct that this is a Black Swallowtail, and it is a male as evidenced by the yellow markings.  Compare your individual to this image posted to BugGuide.  According to BugGuide:  “Males have more extensive broken yellow band.

Note orange and black spot on inner margin of hindwings (Palamedes Swallowtail is otherwise very similar, above, but has no black center in the orange spot).”  The black center in the orange spot is clearly visible in one of your images.

Black Swallowtail
Black Swallowtail
Black Swallowtail
Black Swallowtail

Authors

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  • Bugman

    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.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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