The Secret Life of Giant Swallowtail Caterpillars: An Intriguing Journey

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The giant swallowtail caterpillar is a fascinating creature, known for its unique appearance and intriguing life cycle. This insect plays a vital role in nature as it eventually transforms into the eye-catching giant swallowtail butterfly. Widely found in Florida, this caterpillar can captivate nature enthusiasts and casual observers alike with its development stages and captivating metamorphosis.

One of the most notable features of the giant swallowtail caterpillar is its ability to resemble bird droppings, providing it an effective camouflage against predators. As the caterpillar grows and transitions through its life stages, it eventually sheds its skin to reveal a beautifully colored butterfly. This process, known as metamorphosis, is a marvel of nature, captivating gardeners and scientists alike.

Giant Swallowtail Caterpillar Life Cycle


The life cycle of the Giant Swallowtail caterpillar (Papilio cresphontes) begins with the female butterfly laying her eggs on the leaves of host plants. They are usually laid singly or in small groups. The eggs are:

  • Spherical in shape
  • Yellowish in color
  • Approximately 1 mm in diameter

Larval Stages

Once the eggs hatch, the larvae emerge and go through five developmental stages, known as instars. Each larval stage is characterized by:

  • Growth in size
  • Pattern and color changes
  • Feeding on host plants

An interesting aspect of these caterpillars is their unique appearance, resembling bird droppings to deter predators.


After the fifth instar, the caterpillar enters the pupal stage, also known as the chrysalis stage. During this time, the caterpillar undergoes significant changes, including:

  • Developing wings
  • Body transformation
  • Formation of adult structures

The chrysalis itself is brown and resembles a dried leaf, providing excellent camouflage.

Adult Butterfly Stage

Once the transformation in the chrysalis is complete, the adult Giant Swallowtail butterfly emerges. Key features of the adult butterfly include:

  • Dark blackish-brown wings
  • Yellow spots arranged in bands
  • Hindwing “tail” with a yellow spot
  • Wingspan of up to 6 inches (15 cm)

Adult butterflies primarily feed on nectar from flowers, mate, and begin the life cycle anew by laying eggs on host plants.

Physical Characteristics and Behavior


Giant swallowtail caterpillars have a unique appearance, resembling bird droppings as a form of camouflage to deter predators. These caterpillars display a saddle pattern, which can be seen in the following features:

  • Brown and white coloration
  • Smooth, shiny texture

As they grow, the caterpillars pass through five instars, each with a spiky appearance due to setae, or hair-like structures. Additionally, they possess an orange, snake-like osmeterium, which is a defensive organ they can extend when threatened.

Some host plants for giant swallowtail caterpillars include:

  • Citrus trees
  • Prickly ash
  • Gasplant
  • Sapote

Adult Butterflies

Adult giant swallowtails have dark blackish-brown wings adorned with bands of yellow spots. Their undersides feature primarily yellow, with black, blue, and red markings. They are the largest butterflies in Missouri, with a wingspan between 2½ – 3½ inches.

Comparison between male and female giant swallowtails:

Feature Males Females
Yellow spots Predominant on upperside Less prominent, may be absent
Wing color Dark blackish-brown Dark blackish-brown
Markings Yellow stripes on abdomen Yellow stripes on abdomen

Giant swallowtails, like Schaus’ swallowtail (Papilio aristodemus), are strong fliers and are known to engage in defense against predators such as birds. Their legs are relatively short, contributing to their streamlined body shape, which aids in their agile flight.

Plants and Habitat

Host Plants for Caterpillars

Giant swallowtail caterpillars are found in various habitats throughout North America. During their larval stage, they primarily feed on plants within the citrus family. Some common host plants include:

  • Citrus species (e.g., lime, orange, and lemon trees)
  • Zanthoxylum americanum (prickly ash)
  • Ptelea trifoliata (hoptree)
  • Ruta graveolens (common rue)

In some instances, the larvae have been observed feeding on the leaves of milkweed plants. Incorporating these plants into butterfly gardens or landscape plantings can provide suitable habitat for the giant swallowtail caterpillars.

Nectar Sources for Butterflies

Adult giant swallowtail butterflies rely on nectar sources to provide them with energy. Some popular nectar-rich plants that attract these butterflies include:

  • Zinnias
  • Lantana
  • Milkweed

These flowering plants can be grown in butterfly gardens to create suitable flyways for the adult butterflies. It’s essential to offer a diverse range of nectar sources to support the giant swallowtail population and other butterfly species on the American continent.

Comparison of Host Plants and Nectar Sources

Feature Host Plants Nectar Sources
Plant Type Citrus, Prickly ash, Hoptree Flowers
Purpose Caterpillar food Butterfly energy source
Examples Lime, Zanthoxylum americanum Zinnias, Lantana, Milkweed
Landscape Use Butterfly garden, Landscape Butterfly garden, Flyways

Mating and Reproduction

Courtship and Mating

The giant swallowtail caterpillar’s life cycle starts with courtship and mating. Male and female butterflies engage in an elaborate courtship display. They flutter their wings to showcase their vibrant colors, which play a role in attracting potential mates. Some examples of plants that may be sources of nectar feed for adult giant swallowtails include azaleas, bougainvillea, Solidago, and Lonicera japonica.

Some primary habitats where mating may occur include:

  • Deciduous forests
  • Citrus orchards
  • Central plains

Egg Laying

Once a pair has successfully mated, the female lays its eggs on suitable host plants. Giant swallowtails are often found in citrus farms, where the caterpillars (also known as orangedogs) can feed on the leaves of these plants. The distribution of these butterflies ranges from New England in the United States down to Mexico.

Here are some notable features of egg laying:

  • Females lay their eggs on host plants
  • Citrus plants are preferred host plants
  • Orangedogs feed on citrus leaves
  • Widely distributed across regions

Giant swallowtails and their caterpillars can also be considered pests in citrus orchards, as they can cause damage to the plants. However, their beauty as butterflies also makes them an essential part of biodiversity in these areas.

Regional Distribution and Climate Influence

North American Distribution

The Papilio cresphontes Cramer, or the Giant Swallowtail caterpillar, can be found in various regions across North America. Some of its notable habitats include:

  • Florida
  • Great Lakes states
  • Southwestern United States
  • Ontario, near the Great Lakes of Canada
  • Rocky Mountains

These caterpillars feed primarily on the Rutaceae family of plants. Their distribution extends southwards into Central and South America, as well as the Caribbean.

Climate Change Impact

Climate change has the potential to influence the Giant Swallowtail caterpillar’s habitat and overall life cycle. For example, increasing temperatures may lead to:

  • Larger insect populations due to better conditions
  • Changes in the availability of the Rutaceae host plants

In Florida, a related species called Papilio aristodemus ponceanus, or the Schaus’ Swallowtail, may also experience shifts in their populations due to the altering climate.

Species Potential Impact of Climate Change
Papilio cresphontes Cramer Expanded distribution and increased populations
Papilio aristodemus ponceanus Population shifts due to changing habitat

In conclusion, the changing climate affects not just the regional distribution of the Giant Swallowtail caterpillar but also its interactions with other species and the health of the ecosystems it inhabits.

Conservation and Gardening

Establishing Butterfly Gardens

To support the giant swallowtail caterpillar and other insects, consider establishing a butterfly garden. Such gardens provide essential resources for various butterfly life cycles, including:

  • Nectar plants: Attract adult butterflies and provide energy for reproduction
  • Host plants: Needed for egg-laying and caterpillar feeding

Examples of nectar plants include the butterfly bush and ptelea trifoliata leaf. Caterpillars of giant swallowtails and tiger swallowtails, for instance, benefit from these plants.

Wooded areas are ideal since they offer nectar sources and shelter. Remember that some caterpillars, like the giant swallowtail, defoliate plants during their development. Plant enough host plants to accommodate this without affecting the garden’s aesthetics.

Planning Landscape Plantings

Proper planning of landscape plantings is crucial for the butterfly life cycle and metamorphosis. When selecting plants, consider the following characteristics:

  • Native plants, as they co-evolved with local butterflies and caterpillars
  • Blooming times to provide continuous nectar sources throughout the season
  • A mix of sun and shade for resting and temperature regulation

Comparison of Giant Swallowtails and Tiger Swallowtails:

Feature Giant Swallowtail Tiger Swallowtail
Forewing Span Up to 6 inches Up to 5.5 inches
Dorsal Wing Surfaces Dark blackish-brown Yellow with black stripes
Yellow Bar Several Yellow Spots Continuous Yellow Band
Ventral Wing Surfaces Primarily yellow Yellow with silver markings

Beyond the beautiful sight of butterflies in your garden, conservation efforts also involve preserving habitats for all stages of their development. By providing suitable nectar plants and host plants, you can support these fascinating creatures through their entire life cycle.

Reader Emails

Over the years, our website, 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 – Giant Swallowtail Caterpillars


caterpillars? in Florida
We live in Orlando, Florida and my husband found these caterpillars (?) on our Key Lime Tree. Can you tell us what kind they are? They had amazing long red forked tongues. We are a crowd of bug lovers but we have never seen these and they made us a bit nervous with the long forked tongue. Thank you for any information.
Andrea K

Hi Andrea,
These are Giant Swallowtail Caterpillars, Papilio cresphontes. It is widely accepted that they mimic bird droppings to avoid getting eaten. The red forked “tongue” is a scent organ knows as the Osmetrium. Giant Swallowtail Caterpillars are harmless and develop into beautiful butterflies.

Letter 2 – Giant Swallowtail Caterpillar


Orange Dog pic
Hi Bugman,
Wonderful caterpillar pages. You have helped me finally identify my Orange Dog caterpillars! They love lemon trees in Texas. They are our little rainforest buddies. This one picture October 2006 in the lemon tree. Thank you!
Jill in San Antonio TX

Hi Jill,
We are pleased to know you used our site to identify your Orange Dog, the caterpillar of the Giant Swallowtail.

Letter 3 – Giant Swallowtail Caterpillar on Rue


Subject: Itching to find out what catapillar/moth this is.
Location: Los Angeles, California
October 8, 2015 9:18 pm
I have been looking on tons of websites and google images trying to find out what bug this is. It’s has been in my rue plant for around 3 days now and I haven’t been able to find out what type of bug it is.
Where:Inside( has been outside for 1-2 weeks but only spotted bug inside )
Location: Los Angeles, Calofornia
Please Help!
Signature: From, Ashton

Giant Swallowtail Caterpillar
Giant Swallowtail Caterpillar

Dear Ashton,
This interesting caterpillar is a Giant Swallowtail Caterpillar, and most of the identification requests we receive of this species have the caterpillars feeding on the leaves of citrus, prompting the common name Orange Dog.  If you disturb the Orange Dog, it will reveal an orange, forked organ known as an osmeterium that produces an odor found repulsive by some predators.  The coloration and markings of the Orange Dog causes the caterpillar to resemble a bird’s dropping, which is another form of protective mimicry that helps to ensure that it appears unappetizing to predators.  The adult Giant Swallowtail is a large butterfly native to the North American southeast, but upon the wholesale cultivation of citrus and the adaptation of the species to a non-native food source, the range of the species has expanded, eventually reaching Los Angeles in the late 20th Century.  We have received one previous report of Giant Swallowtail Caterpillars feeding on rue, and we must say we are really curious why you relocated your plant indoors.  Folks who live in places that get a hard frost and severe winters often keep plants outdoors in the summer and then indoors in the winter, but if all predictions regarding El Niño this winter are accurate, it will be a wet and warm winter for Angelinos. 

Letter 4 – Giant Swallowtail at WTB? Office


Normally, at our Mt. Washington office, we see Western Tiger Swallowtails and Anise Swallowtails. Both have proven to be very camera shy. This year, for the first time, we have seen Giant Swallowtails, at least 3 individuals. Our lantana shrubs have gotten to a good size and there is a profuse bloom this year. While lantana is not one of our favorite plants, we have to admit we were very excited it forwarded us the opportunity to get close enough to photograph this Giant Swallowtail today. It should be noted that Giant Swallowtails were first reported in the Los Angeles basin in 1998.

Letter 5 – Giant Swallowtail Caterpillar


Caterpillar Resembles Lizard and Bird Droppings
Fri, Oct 17, 2008 at 5:02 PM Dear Bugman,
Love the website. Maybe you can help me indentify these stranger caterpillars I found this morning terrorizing my baby lemon tree. At first, I thought they were lizards, because of the “eyes” on their backs, and noticed they also look like bird poo . The biggest one erected two giant antenae. I captured some of the larger, more aggressive ones and created a little habitat. Any chance they’ll turn into butterflies?
Thanks! -Kyle
Palm Springs, CA 92262

Giant Swallowtail Caterpillar
Giant Swallowtail Caterpillar

Hi Kyle,
This is a Giant Swallowtail Caterpillar and it will metamorphose into a large lovely brown and yellow butterfly.

Letter 6 – Giant Swallowtail Caterpillar and Citrus Leaf Miner


Interesting Critter
Hi there,
My neighbor referred me to your site when I showed her these strange little creatures that have taken up residence on my orange tree. They’ve probably been there since last year when I first noticed the “snail trail” they leave on the leaves. I never found the bugs and the local nursery wasn’t able to identify the bug that might leave the snail trail. It nearly killed my orange tree last year. So this year everything was going along swimmingly, my orange tree has quite a bounty of fruit, but I started seeing the snail trails again. I’ve been trimming off the affected leaves as I see them. In hunting out damaged leaves I came across a whole branch in the very back of the tree that was covered with these guys. I thought they were bird poop at first! They really look like it. But on closer inspection I realized they were way too uniform and then I see it looks like they even have a face!! Like little dragons. One even reared its head as I was trying to take the picture. Any ideas? Thanks so much.

Hi Susan,
You have two different unrelated caterpillars here. The caterpillar that resemble bird poop are Giant Swallowtails, lovely large brown and yellow butterflies whose caterpillars are known as Orange Dogs. The snail’s trail is being made by the Citrus Leaf Miner, Phyllocnistis citrella, the caterpillar of a tiny moth that feeds on the tissues between the epideral layers of the leaves of citrus trees.

Letter 7 – Giant Swallowtail Caterpillar on Prickly Ash


Subject: What is this bug/caterpillar living on Mesquite Tree?
Location: North Texas
July 29, 2012 11:57 am
There’s multiple bugs of this kind all over a growing mesquite tree. I’m not sure if it’s a caterpillar or what. Whenever we touch it with a stick it has what looks to be two tongues that come out of its head. Then I start smelling something. I don’t know if that smell comes from the bug. It’s summer here in the Northern part of Texas.
Signature: Robert

Giant Swallowtail Caterpillar

Hi Robert,
This caterpillar is aGiant Swallowtail Caterpillar and it will eventually metamorphose into a beautiful adult Giant Swallowtail.  Giant Swallowtail Caterpillars are frequently found feeding on the leaves of orange trees, giving the caterpillars the common name Orange Dog.  The tongue you mention is a scent organ called an osmeterium and it functions to discourage predators by releasing a smell that could be described as unpleasant.  We were confused by your claim that these caterpillars are feeding on mesquite, and the plant in your photo does not resemble mesquite which you can view on Desert USA.  We learned on BugGuide that Giant Swallowtail caterpillars feed on the leaves of Prickly Ash, and upon doing some research, we found photos of Prickly Ash
on the North Carolina Wildflowers, Shrubs & Trees website, and they appear to match the plant in your photo.  We believe your caterpillars are feeding on Prickly Ash, not Mesquite.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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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12 Comments. Leave new

  • Oh scared me so bad when I seen the first one but today seen another and so scared, no one seems to know what it is says it looks like a baby snake, even the company that sprays around our home said they have never seen anything like it, but would charge me $475. To spray our lemon and orange trees. My daughter after sending her a picture looked it up and came up with your sight, I can send pictures from my phone . Someone told me there’s a worm that’s came up from Mexico but don’t know what that one looks like. I live in Southern Ca. I don’t like them killing the leafs on our trees, the Trees aren’t producing much fruit, how do I get rd of these ugly things? Thank you Irma

    • The Giant Swallowtail Caterpillars are not preventing your citrus trees from producing fruit. The drought is a more likely cause.

  • Thank you so much for letting me know these caterpillar ‘s are harmless and not eating our leafs on the fruit trees. As of late I found a large grasshopper on the lemon tree, do they eat on the trees?

    • We are not sure where you got the wrong impression that Giant Swallowtail Caterpillars do not eat leaves. They do in fact eat the leaves of citrus trees, but in our opinion the few leaves they do eat do not produce any lasting damage to the trees.

  • James Wallace
    August 30, 2016 10:40 pm

    please post a Giant Swallo-tail picture.

  • Katie Bauerlein
    September 29, 2016 8:45 am

    How long does it take for the caterpillars to hatch , some of the ones on my citrus trees are at least 2 inches long. It’s hard to believe that a face that ugly can become a beautiful butterfly. The y are eating a lot of leaves but I would rather lose the leaves than the butterfly.

  • I transferred two giant swallowtail catepillars into a large butterfly house that I have. I have numerous varieties in this enclosure. This morning the smallest, approximately 1 1/2 inches, is lifeless. The large, approximately 2 inches seems to be doing fine. Can you tell me what could have possibly happened. The blacktails and monarchs appear to be doing great. Very disappointed as I was looking forward to watching these wonderful creatures form.

    • Possibly parasites. No way to say for certain what caused the demise of one of your caterpillars.

  • do they turn into butterflies?

  • Thank ypu for thos post I have had one on a small citrus tree here in Southern California for a few weeks… I give him drops of water that he seems to drink but didn’t know until today what he was


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