Black Swallowtail Life Cycle: Discover the Fascinating Journey of This Beautiful Butterfly

The black swallowtail butterfly (Papilio polyxenes) is a beautiful and fascinating creature native to North America.

It is commonly found in open areas such as fields, meadows, parks, wetlands, and prairies, and is known for its distinctive black wings adorned with vibrant yellow, blue, orange, and red markings.

Throughout its life cycle, the black swallowtail goes through several stages: from egg to caterpillar, chrysalis, and finally, an adult butterfly.

The eggs, laid singly on host leaves or flowers, are yellow and spherical in shape. The mature caterpillar is an interesting sight, with its green body adorned with black bands on each segment containing yellow-orange spots.

In addition to their remarkable physical features, black swallowtails are known to produce multiple generations per year, making their life cycle even more noteworthy.

Black Swallowtail Life Cycle

Egg Stage

The life cycle of the Black Swallowtail butterfly begins with the egg stage. Eggs are yellow, spherical, and laid singly on host plant leaves or flowers.

Caterpillar Stage

Next, the caterpillar stage occurs and features a mature caterpillar that is:

  • Green in color
  • Possessing black bands on each segment containing yellow-orange spots

Through this stage, the caterpillar feeds and grows before transitioning to the next stage.

Black Swallowtail Life Cycle
Black Swallowtail Caterpillar

Pupa Stage

The pupa stage, also known as the chrysalis, forms a protective casing around the developing butterfly. The chrysalis of the Black Swallowtail can be either:

  • Brown with dark striations
  • Green in color

Adult Stage

Finally, the adult Black Swallowtail butterfly emerges with key features:

  • Females: Larger than males, wingspan 3¼ to 4¼ inches
  • Males: More visible yellow and less blue on wings

Both males and females can be found in open areas such as fields, meadows, parks, and sunny backyards. They reproduce and lay eggs on host plants, starting the life cycle anew.

Host Plants and Habitat

Common Host Plants

Black swallowtail caterpillars primarily feed on plants belonging to the carrot family, Apiaceae. Some popular host plants include:

  • Parsley: A favorite among gardeners, it’s known for its culinary uses.
  • Dill: An herb used for pickling and seasoning dishes.
  • Fennel: A flavorful perennial herb used in cooking and for its medicinal properties.
  • Plants from carrot family (Apiaceae): The swallowtail caterpillars may feed on other plants within the family, depending on availability.
  • Parsley: A favorite among gardeners, it’s known for its culinary uses.
  • Dill: An herb used for pickling and seasoning dishes.
  • Fennel: A flavorful perennial herb used in cooking and for its medicinal properties.
  • Plants from carrot family (Apiaceae): The swallowtail caterpillars may feed on other plants within the family, depending on availability.

Pair of Black Swallowtails (male on left)

Habitat Range and Distribution

Black swallowtails are found in various habitats across North America, extending from Canada to South America. They prefer open spaces, such as:

  • Open fields
  • Roadsides
  • Meadows
  • Parks
  • Wetlands
  • Prairies
  • Sunny backyards

Their range also includes regions around the Rocky Mountains, where they adapt to diverse geographic and climatic conditions.

With several generations per year, black swallowtails emerge from their host plants to collect nectar from flowers like clover, milkweed, and thistles 1.

Physical Characteristics and Behavior

Coloration and Markings

Black Swallowtail butterflies have distinct coloration and markings on their wings. These patterns include:

  • Black wings
  • Yellow spots
  • Green and white bands/stripes on caterpillars
  • Red spot near hindwing tails (with an occasional blue patch)

Female Black Swallowtail

Male vs Female Differences

There are some notable differences between male and female Black Swallowtails:

Males:

  • A row of large, light-colored spots across the middle of wings
  • More yellow and less blue on wings

Females:

  • A row of smaller spots
  • More blue on wings
  • Wingspan: 3¼ to 4¼ inches, larger than males

The sexual dimorphism in these butterflies is evident in their coloration and size.

Flight Patterns and Behavior

Black Swallowtails exhibit specific flight patterns and behaviors, such as:

  • Found in open areas like fields, meadows, parks, wetlands, and prairies
  • Up to 3 or more generations per year
  • Abundance: Common

Some features of their flight behavior include:

  • Fluttering movements
  • Quick, erratic movements when disturbed

Predators and Survival Strategies

Common Predators

Black swallowtails (Papilio polyxenes) have to be cautious of several predators. Some of these predators include:

  • Birds
  • Small mammals
  • Predatory insects

For instance, different bird species are known to prey on black swallowtails in various stages of their life cycle.

Camouflage and Defense Mechanisms

These butterflies employ the following strategies for survival:

  • Camouflage: Through their green coloration, black swallowtail caterpillars blend in with their host plants to evade predators.
  • Defense mechanism: Caterpillars display black bands and yellow-orange dots which serve as a warning to predators.

These features become more pronounced in every instar and lead to Batesian mimicry.

Overwintering Strategies

Black swallowtails have unique overwintering strategies to survive harsh winter conditions.

  • Pupa stage: A black swallowtail overwinters in a state of dormancy called diapause, in the pupa stage.
  • Hidden location: The pupa is usually well-camouflaged on tree bark or stems source.

By employing these survival strategies, black swallowtails achieve a balance between predator avoidance and environmental adaptations.

Conclusion

In conclusion, the Black Swallowtail butterfly is a remarkable emblem of North America’s natural beauty, thriving in open spaces from fields to sunny backyards.

Its life cycle, from the spherical yellow eggs to the vibrant adult stage, is a testament to nature’s wonders. These butterflies have a special affinity for plants in the carrot family, which serve as essential hosts for their caterpillars.

While they face threats from various predators, their camouflage and defense mechanisms ensure their survival.

By understanding and appreciating the Black Swallowtail’s unique characteristics and behaviors, we can further our commitment to preserving these captivating creatures and the habitats they grace.

Footnotes

  1. (https://hort.extension.wisc.edu/articles/black-swallowtail-papilio-polyxenes/) 2

  2. Alabama Butterfly Atlas

  3. Oklahoma State Butterfly

  4. North American Model of Wildlife Conservation
  5. North American Wetlands Conservation

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 Life Cycle

Black swallowtail life cycle
July 9, 2010
I thought you’d enjoy my photographic documentation of the Black Swallowtail life cycle.
Sherry Young
Roe, Monroe County, Arkansas

Black Swallowtail Egg

Hi Sherry,
Thanks so much for sending us your documentation of the early stages of the life cycle of a Black Swallowtail.

Your caterpillar images show two different instars.  Caterpillars molt five times before the chrysalis stage, and each of these instars, in addition to allowing the caterpillar to grow, often demonstrate different coloration and patterns.

INSERT:  July 9, 2010

Black swallowtail 2nd instar
July 9, 2010
Of course, after I submit my 6 pics of the black swallowtail life cycle, I FINALLY get a good picture of what I believe is a 2nd instar!
Sherry Young
Roe, Monroe County, Arkansas
Ed. Note: This was inserted from a later email. End Insert

A mature caterpillar might have no resemblance to an earlier instar.

Black swallowtail life cycle part 2
July 9, 2010
the first email includes egg, early instar (3 I think) and a 5th instar. This one includes 5th getting ready for pupation, chrysalis, and newly emerged butterfly!
Sherry Young
Roe, Monroe County, Arkansas

Black Swallowtail Caterpillar prepares to pupate

Hi again Sherry,
We are thrilled that you rounded out this Life Cycle of a Black Swallowtail so completely.

Your adult butterfly is a female as evidenced by the blue markings on the wings.  Can you provide us with the name of the food plant.  It does not appear to be parsley nor carrots (caterpillars are often called Carrot Worms) but it does look like it might be dill.

Letter 2 – Black Swallowtail: Egg Laying, Eggs and First Instar Caterpillar

Black Swallowtail Baby Mama to Baby Prelude to Black Swallowtail Metamorphosis
Location:  Centreville, VA
August 5, 2010 3:53 pm
Hi – I have been raising Black Swallowtails and Monarchs in my garden for a couple of years now. This year I was lucky enough to see the eggs being laid.

Black Swallowtail Oviposits

I did an egg check everynight so I know for a fact the time line. These were laid on July 31 and hatched the morning of Aug 5. Just so exciting to me!
Bev Basham

Black Swallowtail Eggs

Hi Bev,
This is wonderful documentation for our readership.  We generally hear about Black Swallowtail Caterpillars feeding on carrot greens or parsley, but it appears the food plant in your garden is something different. 

Might it be Queen Anne’s Lace?  Can you please provide us with the identity of the food plant in the event others want to try to support the generation of Black Swallowtails in the home garden?

I think I sent the worst of two pictures of the butterfly laying eggs. This is a better shot. The plant is Bronze Fennel.

I have a butterfly garden at my son’s school and the Fennel we planted there is a different version and it is taking over the world, it’s over 10 ft tall and throws seeds everywhere so we are replacing it next year with this version which seems to be shorter.

I’m so glad you liked the shots. I have a pretty good macro on my camera and really enjoy getting the close up pictures of insects. There is so much more to them than we see with our eyes.

Maybe I did send the right one the first time, once it was gone I had no way of checking. I just got in from checking on the little cats and they have at least doubled in size.

The first day they hatched we had a horrendous thunder storm here with high winds and I thought they got washed away but they were holding on tight. Now if I can just keep the earwigs away.

Letter 3 – Black Swallowtail lays egg on Parsley

Subject: Trying to figure out this butterfly
Location: Omaha Nebraska
July 21, 2013 12:18 am
I’ve narrowed it down to black, spicebush, black morph tiger, or pipevine. I was leaning more toward pipevine. I’ve never seen another like it around here, it was just up on my deck one day investigating the cucumber flowers and it rested for a couple of seconds on my parsley and my basil.

I saw another post up with similar looking butterfly that you identified as a tiger, but tigers don’t have spots on their body like this one does, do they?

I had to take a picture of it through my sliding window because I didn’t want to scare it off. It just didn’t sit still the entire time it was there so this is the best picture I could take as it paused on my parsley pot.
Signature: –lyreragon

Black Swallowtail Ovipositing
Black Swallowtail Ovipositing

Dear lyreragon,
This is a female Black Swallowtail and you have caught her in the act of depositing an egg on your parsley plant.  Compare your image to this photo from BugGuide.  Black Swallowtails exhibit sexual dimorphism, and females have blue markings on the hind wings and males do not. 

According to BugGuide:  “Female, with its large blue patches on hindwings, is a mimic of the Pipevine Swallowtail.”  Your parsley plant is so lush, and you can probably share the leaves with a developing Black Swallowtail Caterpillar

Parsley and other garden plants in the family Umbelliferae (or Apiaceae) like carrots are favored larval food plants.  Another common name for the Black Swallowtail is Parsley Swallowtail and the caterpillar is sometimes called a Carrot Worm.  

Authors

    by
  • 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.

9 thoughts on “Black Swallowtail Life Cycle: Discover the Fascinating Journey of This Beautiful Butterfly”

  1. Pretty girl isn’t she! She emerged this morning. I was so afraid she’d fly off before I could get my battery off the charger, run down the hall and find my camera, put the battery in, and make it back outside. But she didn’t. At first, she was in an odd position where it was difficult to get good pictures. Then she flew over a couple of branches and posed for me. Yes, it is a dill plant, it’s about 30 inches in diameter at the base, and about 5 feet tall. It’s been growing about 5 years strictly as a habitat for my black swallowtails.

    Reply
  2. This is the first time I ever saw this caterpillar on my parsley and have watch them grow (I have two) but now I cannot find them. Where would I find their cocoons? One day the caterpillars were huge and the next day they were gone. I have one more little one that I would like to nurture to a butterfly stage. Is there something I should be doing? I live in CT so I am afraid the weather will get to cool too soon.

    Reply
    • No problem. We wonder if we forgot to email you, which we generally do whenever we post something that is submitted.  For clarification, we generally email, we don’t generally forget to email.

      Reply
  3. We had a black swallowtail butterfly in our Christmas tree. It fell out when my wife was removing the ornaments on January 14. It did not seem to want to feed on sugar water or fruit placed out for it. The black swallowtail died yesterday, having lived for about 11 days.

    Presumably black swallowtails don’t migrate as do monarch butterflies. We were uncertain if it had been hibernating in the tree when it fell out or came out of a chrysalis. At any rate it was nice to enjoy its beauty on January days.

    When we were first married, I placed a BS caterpillar in a jar, it formed a chrysalis, and then emerged some weeks later. My wife had never seen the likes of this and was truly amazed at the butterfly that came from a caterpillar. I’ll never forget the look of amazement on her face when she saw the butterfly in all its glory.

    Reply
    • Thanks for providing this comment. We suspect the Chrysalis was in the tree and the adult Black Swallowtail emerged because of the warmth indoors.

      Reply
  4. We had a black swallowtail butterfly in our Christmas tree. It fell out when my wife was removing the ornaments on January 14. It did not seem to want to feed on sugar water or fruit placed out for it. The black swallowtail died yesterday, having lived for about 11 days.

    Presumably black swallowtails don’t migrate as do monarch butterflies. We were uncertain if it had been hibernating in the tree when it fell out or came out of a chrysalis. At any rate it was nice to enjoy its beauty on January days.

    When we were first married, I placed a BS caterpillar in a jar, it formed a chrysalis, and then emerged some weeks later. My wife had never seen the likes of this and was truly amazed at the butterfly that came from a caterpillar. I’ll never forget the look of amazement on her face when she saw the butterfly in all its glory.

    Reply
  5. I had over 12 BSB in the first stage of their life moving into the second. For as fast as they were eating I knew with all the eggs I still had to go with as well I bought more parsley and dill plants to keep them fed. Every morning I go out to feed my friends birds, chipmunks, squirrels and check on my butterflies. I went to Walmart again to pick up a few more plants and noticed out of about 12 that I had counted that I had 3 left. I looked everywhere for them no luck. Next day went out all of them were gone. I was sick. I never had a problem before last year I raised them had so many had to give them to the enviromental center at the local park. Now my question is what happened to these guys? I have a bunch of eggs now and don’t want to go through this again they just disappeared. Who ate them? I want to protect them the best I can any suggestions? I just want to know where they went and why did something eat them if they stink so bad when you touch them? Please help me. Haven’t had any Monarch visitors as of yet but they will be next for me to babysit. I don’t want to lose any of them anymore.

    Reply

Leave a Comment