Pipevine Swallowtail Caterpillar: Quick Facts & Essential Guide

The Pipevine Swallowtail caterpillar is a fascinating creature worth exploring. As the larval stage of the strikingly beautiful Pipevine Swallowtail butterfly (Battus philenor), these caterpillars have a unique appearance and interesting life cycle that makes them a perfect topic for any nature enthusiast.

Feeding primarily on Pipevine plants (Aristolochia species), these caterpillars play an important role in maintaining the native plant populations across eastern North America 1. Dark reddish-purple with fleshy outer projections, Pipevine Swallowtail caterpillars can be found munching on the leaves of their host plants, preparing for their eventual transformation into butterflies 2.

As they progress through several stages of growth, or instars, the Pipevine Swallowtail caterpillars develop distinct features that help to deter potential predators. For instance, they acquire a toxic substance from the Pipevine plant that makes them unpalatable to birds and other predators 3.

Physical Characteristics

Coloration and Appearance

Pipevine Swallowtail caterpillars exhibit vibrant colors throughout their growth stages. Initially, they are black with red-orange spikes and gradually transition to a dark reddish tone. As adults, Pipevine Swallowtails boast striking iridescent blue on their hindwings.

Caterpillar Stages and Growth

Caterpillars undergo various growth stages called instars. In their early stages, Pipevine Swallowtail caterpillars mimic the appearance of red-spotted purple butterflies for protection.

• Mimics red-spotted purple as defense mechanism
• Appearance changes throughout growth stages

In their later instars, the caterpillars turn solid black with yellow or green markings and spikes. These color changes correspond to their host plants, like the pipevine, as they feed and grow.

• Black with yellow, green markings
• Color changes for camouflage on pipevine plants

Their final appearance as adult butterflies includes a bright blue swallowtail with a single row of light spots on the hindwing. Males showcase more vivid iridescence than females.

• Bright blue on hindwings
• Males more vivid than females

Habitat and Range

Geographical Distribution

The Pipevine Swallowtail (Battus philenor) is a large and striking butterfly native to North America. It can be found in a variety of regions, including the eastern and southern states, as well as the western parts of the United States. In the east, it ranges from Florida up to Kansas, while in the west, it inhabits areas such as California and southwest regions¹.

Host Plants

• Pipevine, or Aristolochia species
• Virginia Snakeroot

These butterflies exhibit a strong preference for their host plants, laying eggs and feeding exclusively on Pipevine (Aristolochia spp.) and Virginia Snakeroot². These host plants not only provide nourishment for the caterpillars but also provide a form of defense, as the toxins from the plants are absorbed by the caterpillars, making them unpalatable to predators.

Importance

Pipevine Swallowtails play a significant role in the ecosystem by being essential pollinators for their host plants. They also provide aesthetic value due to their striking appearance, which can be a catalyst for attracting people to appreciate and care for nature. However, their dependence on specific host plants highlights the need for habitat conservation efforts to ensure the survival of both the butterfly and the plants it relies upon³.

Life Cycle

Eggs and Larvae Development

The life cycle of the Pipevine Swallowtail Caterpillar (Battus philenor) begins with eggs laid by adult females. They typically lay these eggs on the leaves of spicebush or birthwort plants, which serve as their major food source during this stage. The eggs are:

• Small
• Round
• Reddish in color

Once the eggs hatch, the larvae or caterpillars start to grow and develop through several stages called instars. Some of their features are:

• Black and orange bands
• Fleshy projections on their head and body

They feed mainly on the leaves of their host plants providing them with the necessary nutrients.

Chrysalis to Emergence

After the larvae have completed their growth, they form a chrysalis, entering the pupal stage. During this time, they undergo a significant transformation, changing their body structure in preparation for their adult stage – the Pipevine Swallowtail butterfly.

The adult butterflies have unique characteristics:

• Males: Bright iridescent blue hindwings
• Females: Darker hindwings with a row of cream-colored spots

When the transformation is complete, the adult butterflies emerge from the chrysalis, taking their first flight and beginning the next phase of their life cycle.

Behavior and Adaptations

Feeding Habits

The pipevine swallowtail caterpillar feeds primarily on pipevine plants (Aristolochia species) which gives them their name. These plants contain toxic chemicals which the caterpillars can store, making them unpalatable to predators.

Example of favorite plants:

• Pipevine (Aristolochia species)

Comparison of feeding habits with other caterpillars:

Defense Mechanisms

Pipevine swallowtails have a unique defense mechanism called mimicry. They closely resemble black swallowtails and zebra swallowtails, both non-toxic species.

Example of mimicry by pipevine swallowtails:

• Imitating zebra swallowtail coloration and patterns
• Imitating black swallowtail coloration and patterns

Aside from mimicry, pipevine swallowtail caterpillars also possess an osmeterium, a forked gland they can extend from behind their head when threatened. This gland emits a strong odor that can repel predators.

Comparison of defense mechanisms with other butterflies:

Conservation and Gardening

Attracting Swallowtails to Your Garden

To attract swallowtail butterflies such as black swallowtails, spicebush swallowtails and pipevine swallowtails to your garden, plant their favorite native host plants. For example:

• Aristolochia macrophylla: Suitable for pipevine swallowtails

• Birch: Favored by some eastern tiger swallowtails

• Tulip tree: Attractive to giant swallowtails

• Citrus family: Preferred by Canadian and Ontario swallowtails

Remember, swallowtail caterpillars are gregarious and can share plants, so plant a variety of their preferred species.

Supporting Native Species

By planting native species like Aristolochia tomentosa and Aristolochia macrophylla, you can support native pipevines, which are essential for the survival of swallowtail caterpillars. Besides, some swallowtails, specifically the pipevine swallowtail, rely on aristolochic acids found in these plants for their defense mechanism.

Swallowtail caterpillars have several unique characteristics:

• Tough skin: Protects them from predators such as green anoles

• Distinctive appearance: Abdominal segments often have colorful markings

• Distasteful liquid: A defense mechanism to avoid getting eaten

• Metamorphosis: Transform from caterpillars to butterflies through a fascinating process

Caterpillars feeding on aristolochic acid-rich leaves can build up toxins in their bodies, making them distasteful to predators. A key aspect of butterfly gardening, then, is to provide young foliage rich in these compounds.

In summary, here are some pros and cons of planting native pipevines for caterpillar gardening:

Pros

• Attracts a variety of swallowtails to your garden

• Supports native plant and wildlife conservation efforts

• Provides swallowtail caterpillars the essential host plants for their survival

Cons

• Some pipevines may be invasive if not native to your area

Please consider these factors to make informed decisions when trying conservation and gardening in your own backyard.

Other Interesting Facts

Role in Native Cultures

Pipevine Swallowtail caterpillars have been admired by various cultures for their beautiful appearance and unique characteristics. Some Native American tribes believed these caterpillars held spiritual significance in their life cycles and transformation processes.

Scientific Research

The Pipevine Swallowtail caterpillar and its relationship with its host plants, mainly the genus Aristolochia, is an area of great scientific interest.

Range and habitat:

• Found across much of the United States
• Thrives in various habitats, including backyards, meadows, and woodlands

Diet and plant associations:

• Primarily feeds on plants from the Aristolochia genus
• Known to also consume pawpaw trees and sassafras

Protection from predators:

• Sequesters toxins from its host plant
• Stores these toxins, making them unpalatable to predators

Scientists are studying the ways in which these caterpillars utilize the aristolochic acids present in their host plants to protect themselves from predators. This can also serve as a blueprint for developing safer pest control methods that target specific insect species.

Comparison table – Aristolochia vs. other host plants:

This fascinating butterfly species offers a unique aspect to our understanding of insect-plant interactions, both from a cultural and a scientific standpoint.

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 – Pipevine Swallowtail Caterpillar

black caterpillar with red spikes
Location: Tucson, AZ
April 14, 2012 3:41 pm
Hello,
thank you for your great site. I have used it many times to identify bugs around my house. I do not want to waste your time but I have spent a lot of time trying to find my caterpillar on your site and attempted to google its features but was unsuccessful. This caterpillar? was found in our neighborhood. My daughter and I have made it a hobby to collect caterpillars and see what emerges. So far we have only found moths and have been ”hunting” for a butterfly in progress. Our newest addition lovingly called ”spike” by my daughter is yet to be identified. We are in Tucson Arizona and he was found on a weed. He doesn’t seem to have much of an appetite. We went out to get him more of the weed but he just seems to lick it and not eat it. Over night he climbed on a stick to the glass and spit green stuff on it. He is also very inactive and seems to move its ”horns” towards motion as if to try to intimitate. Needless to say this one is much different from the others we have harbored. Do you have any idea?
Thank you so much 🙂
Signature: Mother and daughter nature enthusiasts

Dear Mother and daughter nature enthusiasts,
You caterpillar is quite distinctive and we recognized it immediately as the caterpillar of a Pipevine Swallowtail.  The adult Pipevine Swallowtail butterfly is a beautiful iridescent blue in color and there are orange spots on the under surface of the wings.  According to BugGuide:  “Larvae feed on Aristolochia species. These include “Pipevine” or “Dutchman’s Pipe”, Aristolochia species (tomentosa, durior, reticulata, californica), as well as Virginia Snakeroot, Aristolochia serpentaria. Larvae presumably take up toxic secondary compounds (including Aristolochic acid) from their hostplant. Both larvae and adults are believed toxic to vertebrate predators, and both have aposematic (warning) coloration.”  The plant in your photo does not appear to be in the correct family, so the caterpillar’s reluctance to eat could be because the wrong food is being offered.  We would urge you to try to find a food plant from the Aristolochia family at a local nursery in order to provide the correct food, however, if the caterpillar has matured, it might be preparing to form a chrysalis, in which case it would stop eating prior to metamorphosis.  Here is a photo of a native Pipevine from the Arizona Sonora Desert Museum Digital Library website.

Hello Daniel,
thank you for getting back to us so quickly. I wanted to let you know that we immediately went out to find the right food for the little guy only to be told that local buyers do not buy it and so local nurseries do not grow it. We were devastated. But watching the caterpillars behavior, it appeared as though he was going to form a chrysalis but he just kept falling off.  It looked like he was doing exactly what he was supposed to but could not finish and in the end the poor thing appeared weak and disoriented on the dirt.  We found out that he might eat parsley and immediately offered the food but he rejected it. Looks like this story will not have a good ending after all.  We did find one nursery today who claim to grow the exact plant you describe and we will pick it up tomorrow. It probably will not make a difference for our little guy but we will plant the native pipevine in our yard and maybe we will get to see a happy ending after all. Out of all the caterpillars we have taken in ,this one will be the first to fail. Even though we are both sad for our little “spike”, we will focus on a Salt Marsh Moth (identified on your site) instead, which should emerge for us any day now. Thank you again so much for your help and keep up your great work.
Sincerely,
Mother and daughter nature enthusiasts

Dear Mother and daughter nature enthusiasts,
We are sorry to hear about your lack of success raising the Pipevine Swallowtail Caterpillar.  There must have been a pipevine growing near the vicinity where the caterpillar was originally found, though it is possible it was weeded or removed by a person believing it to be unsightly or problematic is some way.  Often native plants are not as showy in a yard or garden as some cultivated plants, though the cultivated plants do not benefit native wildlife.  Including native plants in a garden scheme is an excellent way to encourage wildlife.

Letter 2 – Pipevine Swallowtail Caterpillar

Caterpillar found in Norther California
Tue, May 26, 2009 at 3:04 PM
Hello,
My son brought home this caterpillar from a close by river. We still have it in his bug catcher with some leaves and other foliage from there and it has since cocooned.
I am curious as to what this is.
Thank you!
Delia Campos
Sacramento, CA at the American River

Hi Delia,
This is the caterpillar of a Pipevine Swallowtail, Battus philenor, a lovely blue-green butterfly with orange spots on the undersides of the wings.

Letter 3 – Pipevine Swallowtail Caterpillar

Another Red Pipevine Swallotail Caterpillar?
Dear What’s That Bug,
I found this in Austin, Texas at our Barton Springs trail. Is this for sure a Red Pipevine Swallotail? If so, what plants do they normally eat? I want to paint this wonderful creature and would very much like to include accurate plantlife in my picture. Thanks for your help!
Denise Garza

Hi Denise,
With caterpillars, the best way to determine food sources it to check the plant the caterpillar was found eating. Your Pipevine Swallowtail caterpillar, Battus philenor, should enjoy eating upon its namesake Pipevine Family plants, such as Dutchman’s Pipe and Virginia Snakeroot. The plants have toxins in the leaves and the caterpillar absorbs those toxins which make them inedible to birds and other preying dangers. Here is a site with some nice images and information.

Letter 4 – Pipevine Swallowtail

butterfly
hi.
i just came across your site for the first time, and i’m enthralled. great job. i didn’t see anything like the butterfly in the attached photo, so i thought i’d send it along. it was taken in the pisgah national forest in north carolina in late summer. thanks, and keep up the good work.
-epk

Hi EPK,
Thank you so much for sending in your gorgeous photo of a Pipevine Swallowtail. It really is a beautiful butterfly.

Letter 5 – Pipevine Swallowtail

What is this blue and black butterfly?
Sun, Oct 26, 2008 at 12:23 PM
I live in Central FL (Orlando area) and saw a black and blue butterfly on one of my sunflowers. It had orange and white spots under his wings. I have looked on a TON of butterfly sites and cannot figure out what kind of butterfly it is. I’d love to know!
Kate
Orlando, FL

Hi Kate,
Your butterfly is a Pipevine Swallowtail, Battus philenor.  Peter Glassberg, in his book Butterflies through Binoculars The West, writes:  “As butterfly gardeners plant more pipevines, the range of this species will probably  expand.”

Letter 6 – Pipevine Swallowtail

Pipevine swallowtail…Female?
Location:  Oklahoma City, Oklahoma
September 11, 2010 1:10 am
Hi there, love, love, love your site! Saw this little lady coming to our garden and thought it was one of the black swallowtails we had helped hatch out earlier, but now I’m thinking it is a pipevine swallowtail? I’m thinking it is a female, but what is your opinion? I’m still just not sure and the anticipation is killing me! We planted an aristalochia vine earlier this month and we are hoping it’s already been found as a host plant?
Thank you so much for your site and for doing all you do, it has helped me so much!
Signature:  Kim

Hi Kim,
Thanks for the compliment.  Because you provided us with photographs showing both the dorsal view and the undersides as well, we can be certain that your sighting is of a Pipevine Swallowtail.  According to BugGuide:  “Male has very iridescent upper surfaces of hindwings. Female has less striking iridescence.”  Iridescence is caused by light, so the quality and direction of the light may affect how iridescent and individual may appear, however, all indications are that this is a female.  Perhaps she was attracted to the Aristalochia that you planted and if you are lucky, you may soon be raising a brood of Pipevine Swallowtail Caterpillars.

Thank you so much for responding and posting my pictures! I’m really excited to have a new type of butterfly in my garden, thank you for helping me I.D. it!

Letter 7 – Pipevine Swallowtail

Brown Butterfly
Location:  Dayton, Ohio
September 18, 2010 9:29 pm
Hi bugman, first, i want to say that you have a great website here! Anyways, today, September 18, I saw this butterfly on a rose bush in our backyard and I cant figure out what kind of butterfly it is.
Signature:  Julia

Hi Julia,
This is an incredibly battered Pipevine Swallowtail.  It appears as though it may have had an encounter with a predator that attacked the wings but failed to grab the body with the vital organs.  This is interesting because much of what we have read indicates that the Pipevine Swallowtail is unpalatable to predators.  You may read more about this lovely butterfly in our archives and on BugGuide.

Letter 8 – Pipevine Swallowtail

Subject: Dark Swallowtail, Gorgeous
Location: Coryell County, TX
October 18, 2015 11:08 am
Hello!
Here is a beautiful dark swallowtail. You’ve helped me with identifying a Black Swallowtail before, thank you!
I looked at your site and at Bug Guide, and I’m thinking that this beauty may be a Pipevine Swallowtail, but I’m far from certain.
It visited the Autumn Sage for the longest time, fluttering like mad almost the entire time.
Thank you so much for your help!
Signature: Ellen

Dear Ellen,
You are correct that this is a Pipevine Swallowtail, and it is not as iridescent as other individuals, which means either the light did not strike it directly, or more likely that it is a female.  According to BugGuide:  “Male has very iridescent upper surfaces of hindwings. Female has less striking iridescence. Underside has a single median row of orange spots which do not touch each other.”  BugGuide also notes:  “The Pipevine flutters its wings incessantly while nectaring–I suspect this is part of its mechanisms for advertising distastefulness. (This is original speculation by the author–PC.) Some others in its complex, notably the Black Swallowtail, seem to do this too.”  That is very consistent with your observations.

Letter 9 – Pipevine Swallowtail

Subject: Pipevine Swallowtail?
Location: Coryell County, TX
November 1, 2016 1:46 pm
Hello, I’m seeing these beautiful butterflies again, almost exactly a year since I last noticed them. I think they are Pipevine Swallowtails. Some others have more blue iridescence when their wings are opened than this beauty; you had said that the ones that are more blue are likely males.
The plant is Autumn Sage (Salvia greggii), and the red variety remains the most popular with the butterflies. I think a dried petal landed on the butterfly’s wings in some of the photos.
Signature: Ellen

Hi Ellen,
Your most recent images of a Pipevine Swallowtail are lovely, and we really continue to enjoy the detailed sighting descriptions you always provide.

Letter 10 – Pipevine Swallowtail Caterpillar

unknown caterpillar
I found this while clearing out a place on our acreage in town. We live on the Texas Coast in the coastal plains, in Calhoun County. There were three of them on a Chinese Tallow branch that I trimmed. I couldn’t find any damaged leaves around them, so they may have just been on the move. I found them on my oleander plant this morning, just “chillin.” Other plants nearby where I found them – dewberry, lantana, Texas persimmon, poison ivy (I didn’t get into that, don’t worry!) Mustang grapevine, tickseed, thistle, wild chives. We have more but they are much farther away from the spot. Hope you can help – my son and I are very curious. I couldn’t find them on BugGuide or What’s That Bug. Thanks –
Michelle

Hi Michelle,
Searching our archives at What’s That Bug?, as well as searching the archives of our favorite identification site BugGuide (and BugGuide is way more organized than we are), can be a daunting task if you don’t know exactly what you are searching for. Both of our sites have numerous images of your species, the Pipevine Swallowtail Caterpillar, Battus philenor. Interestingly, none of the plants you mention are host plants for the caterpillar. According to BugGuide: “Larvae feed on Aristolochia species. These include ‘Pipevine’ or ‘Dutchman’s Pipe’, Aristolochia species ( tomentosa, durior, reticulata, californica ), as well as Virginia Snakeroot, Aristolochia serpentaria. Larvae presumably take up toxic secondary compounds from their hostplant.” Your photo indicates this is probably the final instar for the caterpillar and it is getting ready to metamorphose into a chrysalis. If that is true, the caterpillars might be wandering away from the plant that they were eating in search of the perfect location for pupation.

Letter 11 – Pipevine Swallowtail Caterpillar

bug id, catpartid, and cat photo
Dear Bugman,
WOWEEEEEEE! What an amazing site. It seems like many people like to hang on to their knowledge and it’s wonderful to see someone sharing it so generously. Thank you! I have several questions: 1) What is this bug that’s attached to the monarch butterfly? It is flying OK. SF Bay area
2) I see you have a couple of red pipevine swallowtail cat photos on your site; here’s a black one.
3) I’m creating a website about monarch butterflies and would like to ID some parts. I’ve searched the web high and low for photos of monarch cat spiracles and all I can find are line drawings. Same with mouthparts. Can you confirm these are correct? I’d hate to pass on misinformation!
Sincerely,
Hazel

Hi Hazel,
First, thanks for the sweet letter. We can’t see anything in the Monarch photo, but know that Pseudoscorpions sometimes hitch rides on flying insects. We love your Pipevine Swallowtail Caterpillar photo and are proud to have it. Regarding the labeling of the caterpillar image, you should probably check with a real expert. We are rank amateurs, but in our opinion, the labels look correct.

Letter 12 – Pipevine Swallowtail Caterpillar

caterpiller
Hi. I am wondering if you can identify this caterpillar? for me. Its about an inch and a half long. It was found on a rose bush in the front yard. I live in Kerrville, Texas.
Thanks in advance
Daniel Burney

Hi Daniel,
This is a Pipevine Swallowtail Caterpillar, Battus philenor. Rose is not a host plant, so we can only guess a pipevine is growing nearby.

Letter 13 – Pipevine Swallowtail Caterpillar

Hello, hello…I am a little late sending this in. My eight-year-old found this in our desert ‘yard’ in Tucson, Arizona in October, so that’s an eight-year-old thumb if it helps you size it. I’ve been meaning to look it up for five months now. I await your entemological wisdom.
Amy Gray

Hi Amy,
This is a Pipevine Swallowtail, Battus philenor, Caterpillar. The foodplant consists of both native and cultivated pipevine.

Letter 14 – Pipevine Swallowtail Caterpillar

what’s this bug?
Hi,
Your website is great! I’ve been able to find everything I was trying to look up, except one bug, which I need some help with. I found these little guys while walking in a partially wooded area near Boone, NC. The first one we found was in the stick and leaf debris, and then we found a second one hanging onto a large rock. They were about 1.5 – 2 inches long. Any ideas?
thanks!
Jackie

Hi Jackie,
This is a Pipevine Swallowtail Caterpillar, and its osmeterium, a Y-shaped retractile organ that emits a foul odor, is showing.

Letter 15 – Pipevine Swallowtail Caterpillar

Can you please identify this caterpillar (with picture)
Howdy,
I live in Suwannee County, FL and found this little critter out and about near the front porch this morning. My best guess is that it’s a Gulf Fritillary Caterpillar, however I am most often mistaken as opposed to correct with these assumptions. Would you mind helping me properly identify this caterpillar? As a note, when my dog tried to sniff at it, two spots on it’s head around the vicinity of it’s eyes bulged out big round bright orange spots about the size of two small drops of water. Unfortunately, I couldn’t get the caterpillar to do it’s performance for the camera. Also, I tried looking up this caterpillar in your archives, but many of the pictures wouldn’t load.
Thanks for your time,
Joe

Hi Joe,
What an awesome photo of a Pipevine Swallowtail Caterpillar. The orange horns that appeared are a defense mechanism known as the osmeterium that produce a scent found offensive by predators.

Letter 16 – Pipevine Swallowtail Caterpillar

Puzzled
Dear WTB, we live in northern California, in the foothills north of Sacramento (Penryn). On our walks to the local pond we have been finding a lot of these caterpillars along the trail. Can you help us learn what they are? Thank you,
Jack (6) and Macy (4).

Hi Jack and Macy,
This is a Pipevine Swallowtail Caterpillar. They feed on both native and cultivated pipevine. If provoked, the caterpillar has an interesting defense mechanism. A forked orange scent gland called the osmetrium emerges, looking like a forked horn. The caterpillar then emits a foul odor.

Letter 17 – Pipevine Swallowtail Caterpillar

Subject: What is this bug
Location: Rockport South Texas
August 13, 2012 5:29 pm
We found this bug next to the front door in Rockport, Texas. Can you tell us what it is?
Signature: I don’t care

Dear I don’t care,
This is the caterpillar of a Pipevine Swallowtail.  It is a very distinctive caterpillar and it is highly unlikely that it would be confused with any other caterpillar except possibly its close relative the Polydamus Swallowtail.

Letter 18 – Pipevine Swallowtail Caterpillar

Subject: Pipevine Swallowtail?
Location: Slade, KY; Red River Gorge
August 20, 2012 8:37 am
Good morning! I found this little guy on a hike in Kentucky; Trying to ID him, my best guess is that he is a pipevine swallowtail caterpillar, but he doesn’t look quite the same as the pictures I am seeing of them. Would love some verification! He was about 1.5” long.
Signature: Katy

Hi Katy,
This is indeed the caterpillar of a Pipevine Swallowtail.

Letter 19 – Pipevine Swallowtail Caterpillar

Subject: ID for weird Wrath of Khan caterpiller
Location: Sonoran Desert uplands, Superior, Arizona
March 6, 2013 4:21 pm
I found this at Boyce-Thompson Arboretum in Superior Mountains in Arizona. This is harsh, no water, no live, desert. The arboretum is an oasis of supreme beauty and peace.
As I am desert rat, It was midsummer, midday, when this picture was taken.
Unfortunately I have only this one photo from this angle.
Thanks!
And thanks for going mobile!
Signature: srcbennett

Dear srcbennett,
We are happy to get some positive feedback on our new mobile friendly upgrades.  There was some initial rockiness with the transition.  Your caterpillar is a Pipevine Swallowtail Caterpillar, Battus philenor, and they feed upon Pipevine and other plants plants in the genus Aristolochia. According to the Arizona-Sonora Desert Museum Digital Library website, a native species to the area is Aristolochia watsonii. The adult Pipevine Swallowtail is a beautiful blue butterfly.

Letter 20 – Pipevine Swallowtail Caterpillar

Subject: Catapillars
Location: Vacaville, ca
April 3, 2015 12:33 pm
Please identify this catapillar in the attached pix. Location Vacaville, ca
Signature: Robin

Dear Robin,
It seems it has been years since we posted a new image of a Pipevine Swallowtail Caterpillar, Battus philenor.

Letter 21 – Pipevine Swallowtail Caterpillar

Subject: Pipevine Swallowtail
Location: Tucson AZ
September 9, 2015 8:48 pm
Greetings!
Your excellent site helped me easily identify this caterpillar, but you did not seem to have a photo of a Pipevine Swallowtail on it’s preferred vegetation, which of course is Pipevine! Scientific Name: Aristolochia watsonii English Name: Southwestern pipevine, snakeroot, birthwort, Indian root
Perhaps you will find my photo useful. Use it at will.
Signature: bfrazier

Dear bfrazier,
Thanks so much for sending us your image of a Pipevine Swallowtail Caterpillar, and also for providing the information on the food plant.  We love that the osmeterium, a fleshy forked organ on swallowtail caterpillars that releases what some have likened to a foul odor, is visible in your image.

Letter 22 – Pipevine Swallowtail Caterpillar

Subject: A new creature for me
Location: SW Orange County –
June 3, 2017 1:17 pm
I have lived in NC, in the woods, for over 25 years but this was new. I didn’t even know where to begin looking it up: Beetle? Bug? Caterpillar? Poisonous for my hens or safe?
Signature: Virginia

Dear Virginia,
This is the caterpillar of a Pipevine Swallowtail, Battus philenor.  Adult Pipevine Swallowtails are lovely greenish-blue butterflies with orange spots on the undersides of the wings.  According to BugGuide:  “Caterpillar is quite distinctive, may be a mimic of the tropical onychophorans, called velvet worms. Dark brownish black (occasionally smoky red) with soft fleshy tentacle-like projections, usually red-orange dorsal warts over abdomen. Tentacles on T1 twice as long as those on following segments. ”  We are post-dating your submission to go live later in the month when our editorial staff is away on holiday. 

Thank you!  Yes, what a beautiful butterfly from such a distinctly different caterpillar.  And the caterpillar was so large!  I really appreciate learning more about my friends in Nature.  Virginia Leslie

Letter 23 – Pipevine Swallowtail Caterpillar

Subject: Bright red caterpillar
Location: Southern Arizona ( Santa Cruz county)
August 25, 2017 7:58 pm
I have been noticing these bright red caterpillars during my evening walks.
They are on a plant that I have not found on our property, so that may be their host plant
Do you know what is caterpillar is ?
Signature: Len Nowak ( Salero Ranch )

Dear Len,
This is a Pipevine Swallowtail Caterpillar, and according to BugGuide:  “Larvae feed on Aristolochia species. These include ‘Pipevine’ or ‘Dutchman’s Pipe’, Aristolochia species (tomentosa, durior, reticulata, californica), as well as Virginia Snakeroot, Aristolochia serpentaria. Larvae presumably take up toxic secondary compounds (including Aristolochic acid) from their hostplant. Both larvae and adults are believed toxic to vertebrate predators, and both have aposematic (warning) coloration.”  The adult Pipevine Swallowtail is sometimes called a Blue Swallowtail and it is a gorgeous butterfly.

Letter 24 – Pipevine Swallowtail Caterpillar and Feeding Frenzy of Hackberry Emperors

Pipevine Swallowtail Caterpillars
Hi!
I Googled and got your site on the second hit. On the first hit, I saw an Eastern Swallowtail caterpillar misidentified as a Pipevine Swallowtail caterpillar. I KNOW what an ES looks like; I wasn’t sure what I had eating the Pipevine plants I had just purchased at the Texas Discovery Garden Butterfly Plant sale (duh, right? LOL! Well, I just wanted to be sure!) I didn’t see any shots of the black variant on your site, so am sending you a couple if you can use them. If not, no worries; I don’t have a macro lens, and I was using a zoom lens, so it was hard to get a good depth of field focused. Thanks for your site; I’ve got it bookmarked.
Debbie

PS Have you ever successfully grown Pipevine, the plant? This is my fourth try, and each time the tubors get holes in them and then rot. I’m keeping these dryer, but have already lost one of the three plants I bought. The other two got hammered by this pair of larvae, so I have them in netting now. It hurts when I see butterflies flitting against the net, but if I can’t get them to grow, there won’t be anything to feed the caterpillars next year!
PPS I’m also including a shot of a rotten tomato I threw into the fenceline yesterday; today, it was covered with Hackberry and Mourning Cloak butterflies!

Hi Debbie,
Your afterthought photo of the Hackberry Emperor feeding frenzy is pretty awesome. We will be posting it as well as your Pipevine Swallowtail Caterpillar photo. Sorry, we have never grown pipevine and do not know anything about its horticultural needs.

Letter 25 – Pipevine Swallowtail Caterpillars

Unknown Caterpillar
Location:  Southeast Arizona desert scrub at 3500 feet elevation. N32 deg, 18.3min; W110 deg, 21.5 min
September 13, 2010 10:15 pm
Please identify this caterpillar.
Signature:  Bob Evans

Hi Bob,
These are the caterpillars of the lovely Pipevine Swallowtail, Battus philenor, which you can verify on BugGuide which indicates:  “Larvae feed on Aristolochia species. These include “Pipevine” or “Dutchman’s Pipe”, Aristolochia species (tomentosa, durior, reticulata, californica), as well as Virginia Snakeroot, Aristolochia serpentaria. Larvae presumably take up toxic secondary compounds (including Aristolochic acid) from their hostplant. Both larvae and adults are believed toxic to vertebrate predators, and both have aposematic (warning) coloration.”  We don’t normally think of them as a desert species, so your letter is quite welcome.

Letter 26 – Pipevine Swallowtails Mating

either Pipevine or Spicebush Swallowtails mating.
Hey bugman,
I took this picture earlier today in the Great Smoky Mountains National park of two Swallowtails mating that i thought turned out pretty good. they were right in the middle of the road (well, almost more of a driveway). i thought that was a weird place for them to mate. well hopefully this will be of use to your bug love page. anyway hope you enjoy it.
Michael Davis

Hi Michael,
These are mating Pipevine Swallowtails, and your photo is wonderful

Letter 27 – Pipevine Swallowtails Puddling

Pipevine Swallowtails puddling.
Hey bugman,
I thought I would share with you this picture I took today of some Pipevine Swallowtails puddling. I hope you like it. Thanks so much for an awesome website!!!
Michael Davis

Hi Michael,
Thanks so much for sending us your high quality image of this dramatic puddling event. Swallowtail butterflies are one of the families that frequently gather at water puddles to drink, the benefits being both moisture and minerals. We are sure some of our readers are very curious where this image was taken.

Hey Daniel,
sorry I forgot the location. It was taken in the Great Smoky Mountains National Park near Gatlinburg, Tennessee

Letter 28 – Pipevine Caterpillars and Chrysalis

What is this caterpillar?
Can you identify this caterpillar? I found this in Nov 2007 in the Sutter Buttes of California. It was on the ground about 30 feet from a cluster of pupas that I found attached to a rock. Not sure if they are related. Thank You,
Richard Coleman

Hi Richard,
Your caterpillars are Pipevine Swallowtails, Battus philenor, and the Chrysalis is also from the Pipevine Swallowtail. Your photo does not show the silken girdle thread that keeps the chrysalis upright. This is a characteristic of the chrysalis of most swallowtails.