What Do Black Swallowtail Caterpillars Eat: A Quick Guide for Curious Gardeners

Black swallowtail caterpillars are fascinating creatures, often found munching on various plants. As a gardener or butterfly enthusiast, you might have encountered these little critters on your greenery and wondered about their diet preferences.

Primarily, black swallowtail caterpillars feast on plants within the carrot family (Apiaceae), such as cultivated carrot, parsley, dill, and fennel, making them frequent visitors in your herb garden.

They can be seen consuming the leaves and flowers of these plants, playing a vital role in their life cycle.

With this knowledge, you can now better understand these caterpillars, ensuring a healthy and thriving environment for both the caterpillars and your cherished plants.

What Do Black Swallowtail Caterpillars Eat

Black Swallowtail Caterpillar: Overview

You may have encountered a black swallowtail caterpillar without realizing it. These butterfly caterpillars are various shades of green.

They have narrow black bands on each body segment, which are interrupted by yellow-orange dots.

Their sizes can vary, but they can reach up to 2 inches in length. Black swallowtail caterpillars belong to the Papilio polyxenes species.

Both the male and female black swallowtail butterflies are beautiful, with shiny black wings and colorful markings.

As for their diet, black swallowtail caterpillars consume leaves and flowers from plants in the carrot family (Apiaceae).

These herbs are popular in gardens, which makes it likely for you to find these caterpillars munching on your plants. Don’t worry, though – the plants usually recover.

It’s fascinating to observe black swallowtail caterpillars in your garden. Their eating habits play an essential role in their metamorphosis.

Black Swallowtail Caterpillar

What Do Black Swallowtail Caterpillars Eat?

General Diet

Black swallowtail caterpillars are herbivorous. Their diet consists mainly of leaves and flowers from their preferred host plants that belong to the Apiaceae family.

Apiaceae Family

The Apiaceae family, also known as the carrot family, includes several plants that black swallowtail caterpillars are fond of, such as:

  • Parsley: Caterpillars enjoy munching on its leaves and flowers.
  • Carrot: They relish carrot tops, consuming both leaves and flowers.
  • Dill: It’s a popular host plant, often stripped down by the caterpillars.
  • Fennel: Caterpillars also feed on its leaves and flowers.
  • Queen Anne’s lace
  • Turnips

Citrus and Other Plants

Apart from plants in the Apiaceae family, black swallowtail caterpillars also eat other plant species. Some of these are:

  • Citrus: Although not as common, they can be found on citrus trees.
  • Rue: A popular host in the citrus family, caterpillars feed on its leaves.
  • Tulip tree: Occasionally, black swallowtail caterpillars also consume tulip tree leaves.
  • Golden Alexander: Another favorite, caterpillars savor its leaves and flowers.

In addition to their main diet, black swallowtail caterpillars also benefit from nectar plants.

Some of these include: Clover, Milkweed, Thistles, and Phlox.

These flowering plants offer the butterflies nectar, a vital energy source.

Remember, black swallowtail caterpillars are voracious eaters, but their diet is primarily focused on plants within the Apiaceae family and a few other species.

By understanding their diet, you can provide a suitable habitat for these caterpillars and enjoy watching them transform into beautiful butterflies.

Black Swallowtail Caterpillar

Lifestage: From Eggs to Butterflies

Here’s a quick summary of the lifecycle of black swallowtail butterflies

Larva to PupaEating, growing, and molting through various instarsDill, fennel, Queen Anne’s laceVaries; until fully grown
MetamorphosisTransforming in chrysalis from caterpillar to butterflyNone10-20 days or up to months
Emerged ButterflyDrying wings, flying, mating, and laying eggsNectar from various flowersUntil the end of adult life

Black Swallowtail’s Distinct Features

Characteristics and Coloration

The Black Swallowtail caterpillar has a unique combination of colors. They are primarily green with narrow black bands on each body segment.

To add more vibrancy to their appearance, they also have yellow-orange dots interrupting the black bands.

These eye-catching caterpillars can reach up to 2 inches in length. Their distinct features make them easily recognizable among other caterpillar species.

Adult Black Swallowtail butterflies have a wingspan of 3¼ to 4¼ inches. Males predominantly exhibit yellow markings, while females display limited blue and red markings.

Adult Black Swallowtail

Swallowtail Butterfly Species

There are different species of Swallowtail butterflies, each with its distinct traits and appearance.

Let’s compare the Black Swallowtail with three other species – Zebra Swallowtail, Pipevine Swallowtail, and Spicebush Swallowtail:

SpeciesKey Feature
Black SwallowtailBlack wings with yellow, blue, orange, and red markings
Zebra SwallowtailStriking white wings with black stripes and long tails
Pipevine SwallowtailDark wings with iridescent blue or green hindwings
Spicebush SwallowtailBlack wings with blue and green patches, lighter underside
  • Zebra Swallowtails have white wings with black stripes resembling a zebra pattern, hence the name.
  • Pipevine Swallowtails have dark wings with iridescent blue or green hindwings.
  • Spicebush Swallowtails are recognized by the blue and green patches on their black wings, with a lighter underside.
Zebra Swallowtail

What Eats Black Swallowtail Caterpillars?

Black swallowtail caterpillars, as with many other caterpillars, face numerous natural predators in their environment. Some common predators include:

  • Wasps: Some species of wasps are known to prey on caterpillars, with certain parasitic wasps laying their eggs inside the caterpillars. Once the eggs hatch, the larvae will consume the caterpillar from the inside.
  • Spiders: Many spiders catch and eat caterpillars, including black swallowtail caterpillars, that wander into their webs or come within their hunting range.
  • Birds: Birds are common predators of caterpillars, with species like warblers, orioles, and cuckoos preying on various caterpillar types.


In summary, black swallowtail caterpillars are an essential component of our gardens and ecosystems.

They primarily feed on plants from the Apiaceae family, such as parsley, carrot, dill, and fennel, which are crucial for their development into adult butterflies.

These caterpillars undergo a fascinating lifecycle, transforming from vibrant green larvae to strikingly marked adult butterflies.

Gardeners can play a vital role in supporting these caterpillars by growing their preferred host plants and nectar-rich flowers.

However, it’s important to be mindful of their natural predators like wasps, spiders, and birds, which are part of the ecological balance.

By understanding and fostering the habitat of black swallowtail caterpillars, we not only contribute to the preservation of a beautiful butterfly species but also enhance the biodiversity and health of our gardens.

Reader Emails

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

Letter 1 – Black Swallowtail Caterpillar

Mystery caterpillar
July 6, 2010
This caterpillar has been nibbling my parsley. That’s actually a good thing because I planted it in hopes of attracting Black Swallowtail Larvae. The question is, is that what I have here? I have not found a photo that’s exactly like this guy. The blue doesn’t seem correct for a Black Swallowtail. What do you think?
Chapel Hill, North Carolina

Black Swallowtail Caterpillar

Dear Flatpickr,
Congratulations.  Your efforts to plant parsley to attract Black Swallowtail Caterpillars has been successful.  Your caterpillar is in fact a Black Swallowtail.

Letter 2 – Black Swallowtail Caterpillar

Another caterpillar!
Location: Jacksonville Fl
May 2, 2011 2:47 pm
Hello Bugman!
This one was cleverly concealed in some weeds. I was wondering if you could identify it for me. I’m rather curious as to what it will become.
As always, thank you for your continues efforts!
Signature: Danno

Black Swallowtail Caterpillar

Dear Danno,
In an effort to respond to more emails and make more postings of all the wonderful images we are receiving, our answers are getting shorter.  This is a Black Swallowtail Caterpillar.

Letter 3 – Black Swallowtail Caterpillar

Black and yellow caterpillar
Location: Ocean County NJ ( south NJ )
June 20, 2011 5:45 pm
Hi Bugman,My daughter found this caterpillar in the green houses where she work at moore’s farm market in Beachwood NJ. Do you know what that is, maybe a swallowtail butterfly? Thanks for your time & knowledge 🙂
Signature: Jacqui Moich & family

Black Swallowtail Caterpillar

Hi Jacqui,
You are correct.  This is a Black Swallowtail Caterpillar.  You can feed it parsley or even the tops of carrots from the grocery store.

Letter 4 – Black Swallowtail Caterpillar

Munching the parsley
Location:  Vermont
June 25, 2011
Hi again,
Busy week with critters! I just found these guys on a parsley plant. Any clue what they are?

Black Swallowtail Caterpillar

Hi again KT,
This striking caterpillar is a Black Swallowtail and it also goes by the common name Parsley Worm.  BugGuide notes that the caterpillars are sometimes called Carrot Worms, Dill Worms, Celery Worms and Fennel Worms because they will feed on the leaves of many plants in the carrot family.  They will also feed on Queen Anne’s Lace.

We had a bit of trouble formatting this posting because you bypassed our normal submission form.  While we do not discriminate against emails that we receive that are not on our standard form, occasionally crucial information is omitted.  In the case of this posting, we had to research your previous submissions to provide the proper location for this sighting.

Please use our standard submission form by clicking Ask WTB when you are submitting photos in the future to ensure that our posting process will be more streamlined and efficient.

Letter 5 – Black Swallowtail Caterpillar

Subject: Late season black swallowtail caterpillar
Location: Evergreen Park Illinois
November 9, 2015 5:26 am
First (Fall) black morph black swallowtail caterpillar that I have seen in my garden over the years. I always seem to end up with one or two of them in Fall, but usually they are the standard green color. I put a cold frame up to give it a better chance of pupating as we have had frosts here the last few nights.
Signature: OZ-IL

Black Swallowtail Caterpillar
Black Swallowtail Caterpillar

Dear OZ-IL,
This is a very dark Black Swallowtail Caterpillar, but BugGuide does have some images depicting this dark coloration.


  • 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.

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  • 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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7 thoughts on “What Do Black Swallowtail Caterpillars Eat: A Quick Guide for Curious Gardeners”

  1. It would appear that I’m not the only one who plants parsley in the hopes of attracting black swallowtail butterflies. My family seems to think I’m a little loopy to do this, but now I know I’m not alone!

  2. What do they look for when they are ready to pupate? I move monarch pupas all the time so we can watch them hatch in the house. I suppose I could do the same thing in my 30 degree garage.
    What is the normal pupation time for this swallow tail.


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