Black Swallowtail Butterfly Facts: Quick & Intriguing Insights

The black swallowtail butterfly, scientifically known as Papilio polyxenes, is a majestic and fascinating creature.

Known for its distinctive black and yellow markings, these butterflies are commonly found in North America gracing gardens and meadows.

One remarkable feature of the black swallowtail butterfly is its extraordinary life cycle, which includes four stages – egg, larva, pupa, and adult.

As they grow, their appearance changes dramatically, and they display remarkable adaptability.

For those seeking to attract these beautiful creatures to their gardens, planting their favorite host plants such as parsley, dill, or fennel will make them feel right at home.

Species and Classification

The Black Swallowtail (Papilio polyxenes) is a species of swallowtail butterfly belonging to the Papilionidae family.

Its other names include the American Swallowtail and Eastern Black Swallowtail. Native to North America, their habitat ranges from Alabama to Wisconsin, and areas in between.

Physical Appearance

The Black Swallowtail butterfly exhibits sexual dimorphism, with differences in color and size between males and females:

• Males:

  • Wingspan: 2½ – 3½ inches (6.7 – 8.9 cm)
  • Predominant bright yellow band on wings
  • Row of yellow dots and dashes on wing borders

• Females:

  • Wingspan: 3¼ – 4¼ inches
  • May lack bright yellow band or display it minimally

Comparison Table

Feature	Male	Female
Wingspan	2½ – 3½ inches (6.7 – 8.9 cm)	3¼ – 4¼ inches
Yellow Band on Wings	Prominent	Minimal or absent
Yellow Dots and Dashes	Present	Present

These beautiful butterflies can mostly be found in open areas, such as fields, meadows, parks, wetlands, prairies, and sunny backyards.

Distribution and Habitat

Range in North America

The black swallowtail butterfly, scientifically known as Papilio polyxenes, is native to North America.

This species is widely distributed across the eastern and central parts of the continent, extending from the Rocky Mountains to the eastern coast¹.

Preferred Habitats

Black swallowtails have a preference for open areas that receive ample sunlight. Examples of these habitats include:

• Fields
• Meadows
• Parks
• Wetlands
• Prairies

In addition, they can be found in marshes and sunny backyards². It is essential for their habitat to contain host plants, such as parsleys and fennel, which are vital for their larval development.

Lifecycle and Growth Phases

Eggs

Black swallowtail butterflies lay tiny, spherical eggs on host plants such as parsley, dill, or fennel. These eggs are:

• Creamy white
• Develop a darkish band near hatching

Some eggs get preyed upon by parasitoids or birds.

Caterpillar

When the eggs hatch, the caterpillars emerge. These caterpillars, or larvae, have:

• Bird-dropping appearance (early instars)
• Green with black bands (later instars)

Caterpillars transition through 4-5 stages called instars. They feed on the host plants, growing quickly and eventually shedding their skin.

Pupa

The caterpillar forms a pupa, or chrysalis. Pupae are:

• Green or brown
• Suspended from stems or leaves

During this phase, their body undergoes a significant transformation. In warm climates, this transformation may take only 10-15 days.

Adult Butterfly

Finally, the adult black swallowtail butterfly emerges. Adult features include:

• Wingspan of 2½ – 4¼ inches
• Black with yellow spots (males)
• Black, often with a lesser amount of yellow (females)

Adult black swallowtails live for about 12 days. They seek out nectar-rich flowers and mate, beginning the cycle anew.

Diet and Feeding Behavior

Host Plants for Larvae

Caterpillars of the black swallowtail butterfly, Papilio polyxenes, feed on a variety of plants in the carrot family (Apiaceae) including:

• Fennel: An aromatic herb often used in cooking
• Parsley: A popular herb rich in vitamins and minerals
• Dill: A flavorful herb with feathery leaves
• Celery: A crunchy vegetable high in fiber
• Caraway: A plant producing seeds for culinary use
• Queen Anne’s Lace: Also known as wild carrot or Daucus carota
• Spotted water hemlock: A toxic plant that should be avoided¹

Larvae avoid feeding on milkweed and clover. Becoming vivid green caterpillars with narrow black bands on each body segment, these bands are interrupted by yellow-orange dots².

Nectar Sources for Adults

Black swallowtail butterflies enjoy nectar from a variety of flowers, focusing on the following:

• Milkweed: A group of plants with milky sap and clustered flowers
• Clover: Small flowering plants in the legume family
• Spotted water hemlock: Despite its toxicity for caterpillars, adult butterflies feed on its nectar

These sources provide the energy and nutrients needed for reproduction and migration.

Survival Strategies

Predators and Defense Mechanisms

Black swallowtail butterflies have several ways to fend off predators. One of their primary defense mechanisms is their appearance, which features bright yellow spots on the wings and often mimics harmful butterflies known for their toxins.

This is called Batesian mimicry of another, more toxic swallowtail butterfly. The bright markings can potentially deter predators.

Another defense mechanism is their osmeterium, a specialized organ found in their head. When threatened, the caterpillar can protrude the osmeterium, which releases a foul-smelling chemical to deter predators.

Comparison Table

Defense Mechanism	Details
Batesian Mimicry	Mimics the appearance of harmful, toxic butterflies to deter predators.
Osmeterium	A special organ that produces a foul-smelling chemical for defense against predators.

Impact of Habitat and Human Interaction

The habitat of black swallowtails is generally open areas, such as fields, meadows, parks, wetlands, prairies, and sunny backyards.

They have a wingspan of 3-4 inches with a distinct tail on their hindwings. This tail is not required for flight and can be sacrificed to escape predation.

Human interaction can both positively and negatively impact black swallowtail butterflies. Gardens that offer host plants like parsley and dill can provide a beneficial habitat where black swallowtails can lay their eggs.

Conversely, the widespread use of pesticides and the destruction of their natural habitats can significantly reduce their population.

Identification and Unique Characteristics

Coloration and Patterns

Black swallowtail butterflies are notable for their vibrant colors and patterns. Some key features include:

• Predominant combination of yellow, black, orange, blue, and red colors³
• Rows of yellow spots along the edges of their hindwings and forewings⁴

These colors and patterns not only make the black swallowtail visually striking, but they also have a role in their survival, such as in mating and camouflage.

Cultural and Historical Significance

Symbolism and State Butterfly Status

Black swallowtail butterflies, or Papilio polyxenes, carry significant symbolism in various cultures. For example, they are often associated with transformation and metamorphosis due to their lifecycle from caterpillar to adult butterfly.

They are also admired for their beauty, grace, and elegance, which make them symbols of freedom, joy, and nature’s grand design.

In the United States, the black swallowtail has gained recognition as a state butterfly. It is designated as the state butterfly of Oklahoma, representing the region’s rich fauna and natural beauty.

Interaction with Native Plants

Black swallowtails, also known as parsley worms or parsnip swallowtails, have co-evolved with native plants in their habitats.

They are commonly found from southern Canada, throughout the United States, and into Mexico. In particular, they have a strong affinity towards plants belonging to the family Umbelliferae, such as:

• Parsley
• Carrot
• Parsnip

These plants act as primary hosts for the black swallowtail’s larval stage, known as the parsley worm, which feeds on their leaves.

When the caterpillar transforms into an adult butterfly, it has a lifespan of about 14 days, during which it feeds on flowers to obtain nectar.

Here is a comparison table of the black swallowtail’s interaction with selected native plant species:

Plant Species	Host for Parsley Worm	Nectar Source for Adult Butterfly
Parsley	Yes	No
Carrot	Yes	Yes
Parsnip	Yes	Yes

Black swallowtail butterflies contribute to the pollination of native plants and help maintain the region’s biodiversity.

Thus, by understanding the cultural and historical significance of these insects, we can better appreciate their role in our ecosystems and strive to conserve their populations for generations to come.

Conclusion

In conclusion, the Black Swallowtail butterfly, or Papilio polyxenes, is a marvel of nature, renowned for its striking black and yellow markings and unique life cycle.

Native to North America, it thrives in open spaces, undergoing a transformative journey from egg to adult. Its diet varies across life stages, with caterpillars favoring plants like parsley and dill, while adults seek nectar-rich flowers.

Their vibrant appearance serves as both a defense mechanism and a symbol of transformation in various cultures.

Human interactions can influence their populations, emphasizing the importance of sustainable practices to ensure their continued presence in our ecosystems.

Footnotes

1. https://entnemdept.ufl.edu/creatures/bfly/bfly2/eastern_black_swallowtail.htm ↩ ↩² ↩³

2. https://hort.extension.wisc.edu/articles/black-swallowtail-papilio-polyxenes/ ↩ ↩² ↩³

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

4. Missouri Department of Conservation ↩

Reader Emails

Letter 1 – Two Black Swallowtail Caterpillars

I’m glad we could be helpful Jim. I don’t know if you have Anise Swallowtails, Papilio zelicaon, in your area. The caterpillars of Black Swallowtails and Anise Swallowtails look very similar. Thanks for the photo. It is pretty great.

Letter 2 – Parsleyworm: Black Swallowtail Caterpillar, early instar

Dear Castro Family,
Caterpillars shed their skins going through stages known as instars. This is an earlier instar of a Black Swallowtail Caterpillar, Papilio polyxenes. According to BugGuide, the caterpillar changes dramatically with each molt. They are sometimes called Carrotworms or Parsleyworms since they feed on the leaves of carrots as well as parsley and other plants in that family.

Letter 3 – Zebra Swallowtail and Black Swallowtail

Letter 4 – Pre-Pupal Black Swallowtail Caterpillar and Butterfly Garden

Interesting moths and butterflies?
Location: Windsor, ON, Canada
August 2, 2011 12:10 pm
This doesn’t seem like a question you would normally get, but I am quite interested in Lepidoptera and I am wondering what are some easy ways to attract interesting and beautiful species?
I am currently raising a Black swallowtail caterpillar, which is about to pupate, that I found on my parsley,in my garden.
Next year, I am going to plant a strawberry plant, and I know it will attract many moths, including the Emperor moth. Anyway, are there any nice species that I can attract easily with a host plant? Preferably not a tree. A shrub, plant, flower ..etc will work.
Signature: Sincerely, Dante

Thank you for replying, I want to provide host plants for caterpillars,  preferably simple plants, not trees.
I was thinking about planting strawberries to attract Small emperor moths , but I am not sure if they live in Detroit, MI. Are there any silk moths, sphinx/hawk moths or butterflies that I can attract easily with a host plant?
Sincerely, Dante

Hi again Dante,
We are not certain where you heard about strawberries, but we have our doubts.  Regarding Giant Silkmoths, they do not feed as adults.  Lights will attract them, but you need host trees and you are not interested in planting trees.  Hawkmoths can be attracted by flowers with nectar, like bee balm, honeysuckle and nicotiana.  Tomato plants will attract species that feed on tomato leaves.  Good Luck.

Letter 5 – Parsley Worm is Black Swallowtail Caterpillar

Subject:  Caterpillar
Geographic location of the bug:  Gettysburg, PA
Date: 07/24/2018
Time: 06:08 PM EDT
Your letter to the bugman:  What is this. Just found it on my parsley plant.
How you want your letter signed:  Tina

Dear Tina,
This is a Black Swallowtail Caterpillar, and some common names are “Dill Worm, Parsley Worm, Celery Worm, Carrot Worm, Fennel Worm” according to BugGuide, because “The common names for the caterpillars vary because they can be found on many important cultivated plants in the Carrot Family. Pick the host plant, add the word ‘worm’, and you have another common name that has probably been used and published somewhere.”

Letter 6 – Parsley Worm is Black Swallowtail Caterpillar

Subject:  Electric Caterpillars Eating Parsley
Geographic location of the bug:  Mantaloking, NJ
Date: 08/04/2019
Time: 11:47 AM EDT
Your letter to the bugman:  Dear Bugman,
These neon caterpillars were enjoying a parsley buffet in a backyard near the bay in Jersey. Wondering what they will be after they transition…
How you want your letter signed:  Melanie on the Irish Chain

Dear Melanie on the Irish Chain,
This is a Black Swallowtail Caterpillar, often called a Parsley Worm or Carrot Worm by home gardeners because of their host plants.  The adult Black Swallowtail is a beautiful butterfly.