How Long Do Tiger Swallowtail Butterflies Live: Unveiling Their Lifespan Secrets

Tiger swallowtail butterflies are a captivating sight in gardens and natural environments. The Eastern tiger swallowtail, specifically, is a common and striking species found east of the Mississippi river and into the Great Plains states, with some populations reaching as far as Mexico ¹. These large insects display vibrant yellow colors and unique black stripes on their wings ².

Understanding the life cycle of the tiger swallowtail butterfly gives insight into its longevity. The adult butterfly has a limited life span, and various factors can influence its duration. In general, their life expectancy ranges from a few days to several weeks ³. It is essential to note that seasonal conditions may also affect their longevity.

Tiger swallowtails undergo four life stages: egg, larva (caterpillar), pupa (chrysalis), and adult butterfly. Each stage is accompanied by unique features and growth, ultimately leading to their transformation into a fully developed adult. By understanding their life cycle and environmental challenges, we gain valuable knowledge of these fascinating creatures. ⁴

Life Cycle of Tiger Swallowtail Butterflies

Eggs

Eastern Tiger Swallowtail butterflies lay their eggs on the leaves of plants that the caterpillars will eat. These plants are typically in the family of trees and shrubs, such as wild cherry, tulip tree, and birch. Some key features of their eggs:

• Color: green initially, turning brownish-yellow as they mature
• Size: about 1mm in diameter

For example, a female Tiger Swallowtail may choose to lay her eggs on a wild cherry tree leaf.

Caterpillars

The caterpillars emerge from their eggs and immediately start to consume the leaf on which the egg was laid. Key characteristics include:

• Early stages: resemble bird droppings for camouflage
• Later stages: green with two large black and yellow false eyes
• Preferred food: leaves of host plants

A caterpillar will typically spend 2-4 weeks in this stage, eating and growing before they form a chrysalis.

Chrysalis

When the caterpillar is ready, it forms a chrysalis, or pupa, as a protective casing for its metamorphosis. The chrysalis stage has the following features:

• Color: brown or green, depending on surrounding environment
• Attachment: hangs from a silk girdle on a twig or leaf
• Duration: varies depending on environmental factors, can be weeks or months

For instance, a caterpillar may form a brown chrysalis if it is on the trunk of a tree to blend in with the environment.

Adult Butterflies

The adult Tiger Swallowtail butterflies emerge from the chrysalis with their striking features:

• Wingspan: 3.12 to 5.5 inches
• Colors: yellow with four black bands on the front wings
• Habitat: anywhere east of the Mississippi river, and in some Great Plains states and Mexican states

The adult butterfly stage is the final part of their life cycle, during which they feed on nectar, mate, and lay eggs to complete the cycle. The adult lifespan is typically 2-3 weeks, sometimes longer depending on factors such as weather conditions and availability of food.

To summarize, here is a comparison table of the various stages of the Tiger Swallowtail’s life cycle:

Physical Characteristics and Sexual Dimorphism

Males vs. Females

The Eastern Tiger Swallowtail butterfly is a sexually dimorphic species. Males are typically smaller in size, while females tend to be larger.

• Male size: approximately 3.1 to 5.1 inches (7.9 to 13 cm)
• Female size: approximately 3.5 to 5.5 inches (8.9 to 14 cm)

Coloration and Patterns

Eastern Tiger Swallowtails exhibit distinct coloration and patterns between males and females. Males have yellow and black stripes, while females can have two color forms: yellow with black stripes, and a dark form with blue shading.

Males

• Yellow color
• Black stripes

Females

• Yellow or dark form (black with blue shading)
• Black stripes in the yellow form

Here is a comparison table for Eastern Tiger Swallowtail coloration and patterns:

These butterflies’ distinct coloration and patterns serve various purposes, including attracting potential mates and warding off predators.

Distribution and Habitat

Geographical Range

The Eastern Tiger Swallowtail butterfly (Papilio glaucus) can be found in a wide range throughout eastern North America, stretching from the Mississippi River to the East Coast of the United States, and into the southern parts of Canada¹. Meanwhile, the Western Tiger Swallowtail (Papilio rutulus) inhabits riparian forests and urban areas with host plants in the western regions of North America².

Host Plants

Eastern Tiger Swallowtails are known to lay their eggs on a variety of host plants, including:

• Wild cherry
• Tulip tree
• Aspen

In contrast, Western Tiger Swallowtails use plants from similar genera as host plants in their urban habitats².

Nectar Sources

The adult butterflies from both species feed on various nectar sources. Eastern Tiger Swallowtails, for example, may enjoy flowers like:

• Milkweed
• Wild cherry blossoms

Western Tiger Swallowtails are less specific and can feed on nectar from many flowering plants³. They prefer wetter environments and can often be found in gardens and parks.

Behavior and Reproduction

Mating

Eastern tiger swallowtail butterflies have an interesting mating behavior. Male swallowtails use a specific method to find females. They patrol areas in search of females, detect the female’s pheromones, and approach the female for copulation.

Puddling

Adult male swallowtails participate in an activity called “puddling,” where they congregate on wet soil or mud near water sources to extract minerals and salts. These nutrients are vital for reproductive success and overall health. Puddling is more common in males, as they pass on these nutrients during mating to females.

Flight

• Eastern tiger swallowtails are strong fliers.
• Flight period: June through July.
• Preferred habitat: wetter areas.

These butterflies take flight individually or in small groups during their active season, and they prefer wetter areas such as riverbanks and streams. Their powerful flight allows them to cover large distances in search of flowers for nectar and suitable host plants for their larvae.

Wing Patterns

-Eastern tiger swallowtails have distinct wing patterns.
-Male wingspan: 3.1-5.5 inches, Female wingspan: 4.1-5.9 inches

The yellow and black striped pattern on the wings of male eastern tiger swallowtails mimics the appearance of a tiger, while female tiger swallowtails display sexual dimorphism, with either a similar yellow pattern or a darker form with blue spots.

Diet and Predators

Feeding Habits of Butterfly

The diet of a tiger swallowtail butterfly mainly consists of nectar from various flowering plants. Adult butterflies are known to feed on a diverse range of nectar plants, such as willow, cottonwood, and magnolia trees ¹.

Caterpillars of this species have specific host plants where they feed on leaves, including:

• Willow
• Cottonwood
• Magnolia

Predators and Defense Mechanisms

Tiger swallowtails have several predators, including snakes and birds ². To defend themselves, they adopt various mechanisms, such as:

• Camouflage: Their coloration helps them blend into their surroundings, making it difficult for predators to spot them.
• Mimicry: Some female tiger swallowtails have dark coloration that closely resembles the toxic pipevine swallowtail, deterring predators from attacking them ³.

Subspecies and Related Species

Western Tiger Swallowtail

The Western Tiger Swallowtail (Papilio rutulus) is a butterfly found primarily in the western United States. They are known for their bright yellow color with black stripes, similar to their Eastern counterpart. Adult butterflies typically take flight from June through July and can be found in wetter areas like Pacific coastal regions throughout much of the year.

• Bright yellow with black stripes
• Prefers wetter areas

Canadian Tiger Swallowtail

The Canadian Tiger Swallowtail (Papilio canadensis) is a species found in the Great Plains and northern regions of North America. Like other swallowtails, it has a yellow and black striped pattern. The distribution of the Canadian Tiger Swallowtail overlaps with the Eastern Tiger Swallowtail, although Canadian Tigers prefer colder climates.

• Yellow and black striped pattern
• Overlapping distribution with Eastern Tiger Swallowtail

Pipevine Swallowtail

The Pipevine Swallowtail (Battus philenor) is another related species, distinguishable by its iridescent blue or green wings. It is named after the pipevine plant, which is the primary food source for its larvae. Unlike other swallowtails, they don’t have the typical yellow and black pattern.

• Iridescent blue or green wings
• Larval food source: pipevine plant

Appalachian Tiger Swallowtail

The Appalachian Tiger Swallowtail (Papilio appalachiensis) is a hybrid species found in the Appalachian Mountains. It is believed to have evolved from hybridization between the Canadian and Eastern Tiger Swallowtails. The hybrid is identified by its size, which is intermediate between its parent species.

• Hybrid of Canadian and Eastern Tiger Swallowtail
• Intermediate size between parent species

Comparison Table

Conservation and Human Interaction

Garden Planting

The Tiger Swallowtail butterfly is a species that benefits from urban parks and gardens. When selecting plants for your garden, consider adding wild black cherry and lilac, as they are attractive to this butterfly species. Some benefits of attracting these butterflies include:

• Pollination of flowers
• Natural pest control
• Aesthetic value

Notably, the Tiger Swallowtail is polyphagous, meaning it feeds on various plants, increasing the potential interactions with different plant species in your garden.

State Insect

In the United States, the Tiger Swallowtail butterfly serves as the state insect for several states, including:

• Alabama
• Georgia
• North Carolina
• South Carolina

This cultural importance and recognition make it vital to protect their habitats, notably in urban parks and gardens, which play an essential role in their conservation.

Cultural Significance

The Tiger Swallowtail butterfly holds significant cultural value in various regions around the world. For example, in Mexico, it is known for its unique beauty and is often used as a symbol in artwork and literature.

Capturing the beauty of the Tiger Swallowtail in a photograph is popular among nature enthusiasts. The Papilionidae family, which the Tiger Swallowtail species belongs to, is regarded for their aesthetic appeal, making them a popular subject for photographers.

Besides their visual appeal, Tiger Swallowtails play an essential role in ecosystems. They help balance species populations by consuming sodium ions and amino acids, which maintains the nutrient cycles within an environment. -*-

Additionally, Tiger Swallowtails contribute to plant reproduction and growth by pollinating flowers as they gather nectar.

Overall, the conservation and human interaction with Tiger Swallowtail butterflies enrich both the natural environment and human culture. By incorporating plants that attract these beautiful creatures into urban parks and gardens, raising awareness of their importance, and celebrating their cultural significance, we can help protect and conserve these species to allow future generations to appreciate their beauty and ecological contributions.

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 – Male and Female Eastern Tiger Swallowtail

Subject: Tiger Swallowtails
Location: Western Kentucky
September 9, 2012 6:47 pm
Dear Staff,
I have a question about the Tiger Swallowtails. I know there is an Eastern, a Western, light phase, dark phase and so on. I live in Kentucky and around the area I have seen different colors on the Tiger Swallowtails. I wondered why some have a lot of blue and some have none at all. I am including three shots of the Tiger Swallowtails from around the area. Two are from 2010, and one from 2011. I have wondered about the reason for the areas of blue on some.
Signature: Janet Fox

Hi Janet,
This is a very interesting and complicated question and we will try to the best of our ability to answer it correctly.  There are at least five recognized Tiger Swallowtail species:  Pale Tiger Swallowtail, Western Tiger Swallowtail, Canadian Tiger Swallowtail, Appalachian Tiger Swallowtail and Eastern Tiger Swallowtail as well as a similarly marked western species known as the Two Tailed Swallowtail.  We believe your individuals are Eastern Tiger Swallowtails.  Males lack the dusting of blue scales on the lower wings that are present in the female, so the blue markings can be used to differentiate the sexes.  You can get a full explanation of these differences on BugGuide.  To further complicate things, BugGuide reports hybrids that might occur where the ranges of the different species overlap.

Daniel,
Thanks so much for taking the time to answer me.  I have been taking pictures of bugs for a few years now.  I had so many that I could not name and I spent a lot of time trying to find them on your site.  I broke down and bought a Kaufman Field Guide to Insects of North America.  I still have a couple I can not find in there.  But I am happy to report most of my photos do have names.  Your site is a great resource to me for information and confirming my possibles.  When I started taking random pictures of bugs, I never realized there were so many kinds.  I also didn’t know so many were so pretty.
Thanks again.
Janet

Letter 2 – Female Tiger Swallowtail: Dark Form

Posted (09/01/2007) Female Tiger Swallowtail?
Hi again!
Am I correct in believing that this is a "camouflaged" female Tiger Swallowtail mimicking the poisonous Pipevine Swallowtail? These pic was taken today and the butterfly is on a Mexican Sunflower (Tithonia Rotundifolia ). She was such a good subject, I could have taken pics of her all day long. I did find several pics of morphed female Tigers on your website but none of them had their wings open. How do you tell the difference between a morphed female Tiger Swallowtail and a Spicebrush Swallowtail? Is it that the Spicebrush has more blue "trailing" the orange spots on the inner row of orange spots on the underside of the lower wing? The butterflies are quite similar with their wings up. Thank You!!
Jacqui
Middle Georgia
P.S. I used to think it was SpiceBUSH Swallowtail, not SpiceBRUSH — LOL!! I guess I was crossing my bushes and my butterflies.

Hi Jacqui,
We were deleting some old emails and came across your great questions and wonderful photos that somehow slipped through the cracks when it was first sent. It was a busy time and the last full day of mom’s yearly visit. According to BugGuide, the: “dark phase occurs in females through much of range, especially in southern states. The stripes are still faintly visible from some angles. The black females may be distinguished from other swallowtails from below, by the absence of the band of orange spots on the hind wing seen on Black and Spicebush Swallowtails, and lack of iridescent blue of Pipevine Swallowtails. ” The stripes are more visible on the underwings as your photos illustrate. Also, we have seen both Spicebush and Spicebrush used, but Spicebush is more commonly accepted since it is the food plant of the caterpillar.

Letter 3 – Golden Buprestid and Tiger Swallowtail: Home Intruders

Insects that hatch in houses in winter
Dear Bugman,
For an “art project” your marvelous site is very helpful to naturalists who get asked, what’s this bug that hatched in my house this winter? I’m pasting in 2 photos for you. The first is of a Golden Buprestid (I think) that came right out of my friend Sandy’s cutting board one morning. She’d had that home-made board (probably Ponderosa pine), for 8 years, and pounded, carved, sliced n’ diced on it all that time. Then one recent morning out came this beauty! The 2nd photo is of a Swallowtail butterfly that hatched out on some potted plants in a windowsill in the building here in Moscow, Idaho, where I go for my massage appointments (lucky me). My questions are — have you got any great tales of the long-lived Buprestid larvae popping out as adults in people’s homes? For the Swallowtail, how would a pupa end up on a geranium that’s never been outside? And lastly, what do we tell people who want to feed or keep alive their unexpected and stunningly beautiful winter visitors? The Swallowtail died within the week. The Buprestid has been in a little cage with some fir needles and has made it for a week so far. Thanks for your replies!
Sarah Walker
Moscow, Idaho

Hi Sarah,
Thank you for sending your interesting anecdotes. We have heard of certain wood boring beetles emerging many years after the wood was cut. Sometimes they emerge from furniture and other times from wood paneling. Many caterpillars leave their host plant and wander in search of a place to pupate. Sorry, we have no advice on keeping off season guests alive. Eric Eaton wrote in with this information: “Daniel: What a fabulous story about the beetle emerging from the cutting board! It is indeed a “golden buprestid,” Cypriacis aurulenta (formerly Buprestis aurulenta). The record age for one is an adult that emerged from a baseboard(?) in a Canadian building fully 51 years after the building was erected! Why milled lumber forces such an extended life cycle in woodborers is a mystery, at least as far as I know. Normally, the life cycle would be no more than 2-5 years. Eric”

Letter 4 – Male Eastern Tiger Swallowtail Butterfly

Butterfly
Location: cape cod
August 17, 2011 10:38 pm
Hi bugman. I found this butterfly sitting on a bush out in my yard.
Signature: max

Hi Max,
This beautiful butterfly is an Eastern Tiger Swallowtail and he is a male as indicated by the lack of blue on the lower wings.  Here is a photo of a female Tiger Swallowtail from our archives.

Letter 5 – Mating Sexually Dimorphic Eastern Tiger Swallowtails

Canton, GA
Someone in our office found these two on her car one morning
on her way in. I’ve identified them as the sexually
dimorphic Papilio glaucus more commonly called Eastern Tiger
Swallowtail. Is that a correct identification? Also, it is
an interesting picture thought you might enjoy.
Michelle Gunter

Hi Michelle,
Thanks so much for sending this beautiful image of mating
sexually dimorphic Eastern Tiger Swallowtails. The dark individual
is a female, and a small percentage of Eastern Tiger Swallowtails
show this color pattern. We have also received images of intermediate
stages: not quite light, and not quite dark.

Letter 6 – Mating Sexually Dimorphic Tiger Swallowtails

Subject: Mating Swallowtails
Location: New Cambria, Missouri
July 25, 2014 3:45 am
I took this photo yesterday of these two different (species?) of Swallowtails mating. Is this common? Can it result in viable offspring or a hybrid butterfly?
P.S. LOVE this website. It has been very informative.
Signature: Denise

Dear Denise,
The Tiger Swallowtails in your image are actually the same species.  The dark individual in the image is the female.  Though most female Tiger Swallowtails are yellow with black stripes, a small percentage of female Tiger Swallowtails are known as dark morphs, and even though the bold tiger striping is not evident, close inspection reveals a black on black striping pattern.  There are also examples of transitional coloration that fall between the light and dark morphs, and even more unusual are hermaphroditic gyandromorphs that contain traits of both sexes and which sometimes exhibit a combination of light male attributes and dark female attributes.  One final note, even without considering black morphs, Tiger Swallowtails are a sexually dimorphic species.  Female Tiger Swallowtails have blue dusting on the hindwings while male Tiger Swallowtails lack the blue coloration.  We are highlighting your posting on our scrolling feature bar. 

Letter 7 – Mystery Plant: Nectar bounty for Monarch, Tiger Swallowtail and others

Busy Bush
Location:  North Middle Tennessee
August 3, 2010 1:12 pm
Hi Daniel,
I don’t know the name of these bushes they are a nuisance. Grow almost everywhere have thorns that tend to break off in your hand, these flowers (sweet smelling) are followed by berries (black) that stain. That being said right now they are the main attraction in the neighborhood for all sorts of insects. Bees, wasp, flies, moths, butterflies are all competing for the nectar. I have spent hours standing in one spot photographing all sorts of critters. (I do keep my distance cause the bees are ”packing heat”) However they all seem to just have eating on their minds, haven’t noticed any agressive behavior from any of them toward each other or me for sticking my nose into their business. One absence I have notice from the nectar feast is ”Honey Bees” they are all but extinct around here. I realize this is off topic but I found all of the bush’s activity interesting. Thanks for all you do and have a wonderful day.
Richard

Hi Richard,
What, pray tell, is “off topic” in your letter?  We find it to be spot on topic.  We hope one of our readers can provide the name of this plant, because though you have provided some of its negative qualities, it seems the benefits of providing a bounty of nectar for insects and probably berries for birds would make it a very desirable plant for nature enthusiasts who populate their gardens with plants that will attract wildlife.  Among the visitors you have documented are a Monarch Butterfly, a Tiger Swallowtail Butterfly, Bumble Bees and an Ailanthus Webworm Moth.  We are sad to hear of the demise of the local Honey Bee population.  We can only hope that Colony Collapse Disorder (CCD) will run its course and the surviving bees will have the genetic resistance to make a comeback.

Note to Readers: If you recognize this plant, please provide a name.

August 5, 2010 10:04 am
Daniel:  I wonder if the thorny, flowering plant with Tiger Swallowtail and Ailanthus Webworm Moth on it could be
Hercules’ Club (Aralia spinosa) or (less likely) Devil’s Club (Oplopanax horridum).
Best,
Dave Fallow in Madison Wisconsin

Hello Daniel,
I never though it would be of any interest to anyone but since you posted it I became corrious and did a bit of internet searching. The bush is a :”Devil’s Walkingstick” or “Aralia spinosa L.” here is a link to the plant:
http://plants.usda.gov/java/profile?symbol=ARSP2&photoID=arsp2_008_avp.tif
Thank you for all you do and have a wonderful day.
Richard

Letter 8 – Photo of Tiger Swallowtails resembles Damian Hirsch painting

Three Swallowtails
These three buddies came to my backyard together every afternoon
at 4:00 PM

We love the way your photo resembles a Damian
Hirsch Butterfly Painting.

Letter 9 – Possibly Western Tiger Swallowtail

Subject:  Oregon Swallowtail
Location:  Oregon
December 14, 2013
Your Welcome!
I’ll enclose the Oregon versions (it’s the state insect there). Sadly my camera then was not as good.
Signature: Curious Girl

Hi Curious Girl,
Thanks for sending this image of a Swallowtail you photographed in Oregon, however, it is noticeably different from the Old World Swallowtail images we posted a few days ago.  The Old World Swallowtail, Papilio machaon, is also found in North America, and according to BugGuide:  “The various subspecies included here under the name Papilio machaon have been (and contunue to be) treated differently by different authors. The most commonly seen alternate classification would have the subspecies bairdii, dodi, oregonius, and pikei placed as subspecies of a distinct species Papilio bairdii, and the more boreal subspecies would be left under the species Papilio machaon. There are good reasons for doing this, but the majority of workers currently place them all under one species. There are also still some people who would prefer to see each name treated individually at species ranking, though this is not widely accepted practice. The result is that these butterflies may be listed under a number of different name combinations, depending upon the preferences of the individual author.”  According to State Symbols USA, the Oregon Swallowtail is the state insect of Oregon, but according to BugGuide, it is actually a subspecies of the Old World Swallowtail.  The Old World Swallowtail is easily confused with the Anise Swallowtail, Papilio zelicaon, which is also found in Oregon.  The butterfly in this photograph is neither of those species, and though we are uncertain of its exact identification because of the quality of the photo, we are guessing it is either a Western Tiger Swallowtail, Papilio rutulus, or a Pale Swallowtail, Papilio eurymedon.

Letter 10 – Pre-Pupal Tiger Swallowtail Caterpillar

bald looking caterpillar
Location: western maryland
August 10, 2011 7:57 pm
What is this strange creature?
Signature: curious

Dear Curious,
This is a Tiger Swallowtail Caterpillar, and its dark purple coloration indicates that it is pre-pupal and about to begin metamorphosis into the chrysalis stage.  When a typically green Tiger Swallowtail Caterpillar nears the end of its stage as a caterpillar, it loses interest in feeding upon the leaves of its host tree, including, according to BugGuide, black cherry, tuliptree, sweet bay and swamp bay, and it begins searching for a suitable location for pupation, often leaving the tree.  At this time, the green coloration often changes to orange or dark purple, like the color of your individual.  Here is a matching photo from BugGuidefor confirmation.

Letter 11 – Prepupal Tiger Swallowtail Caterpillar

Subject: Catapillar ?
Location: Montclair, NJ 07042
August 16, 2017 2:52 pm
Hello Bugman 🙂
I saw this lil critter on the sidewalk in Montclair, NJ . Can you tell me what kind of bug it is ? Thank you !
Signature: Angela- I️Bugs

Dear Angela,
The last time we posted an image of a prepupal Tiger Swallowtail Caterpillar, the posting got 37 Facebook “likes” and we hope your posting can beat that.  When they are still growing and feeding, Tiger Swallowtail Caterpillars are green to blend in with the leaves.  When pupation time approaches, many individuals turn brown or orange.

Letter 12 – Probably Tiger Swallowtail Caterpillar

Subject: Strange bug
Location: Fairfax Va
September 11, 2016 2:52 pm
Saw this at our pool today in Fairfax va….it has suction cup like feet…seemed to be sensing with a probiscus like nose that had thing extending out of it…
Signature: Finbar

Answered the question I believe it is
This….  2010/10/13/swallowtail-caterpillar-two-tailed-swallowtail-or-western-tiger-swallowtail/

Dear Finbar,
While your caterpillar looks very similar to the link to our archives you cited, your Tiger Swallowtail caterpillar is most likely the originally described Eastern species, Papilio glaucus.  While the appearances of the caterpillars of the three different Eastern species, we concede that you might have encountered an Appalacian Tiger Swallowtail caterpillar as you are within the BugGuide listed sightings, though there are no actual Virginia sightings.  You are a little too far south to likely be the Canadian Tiger Swallowtail, which BugGuide reports only documented sightings considerably north of you, with the closest being Pennsylvania.

Letter 13 – Probably Two-Tailed Swallowtail Caterpillar

Subject: What type of swallowtail?
Location: Eagle Point, Oregon 9752r
August 18, 2016 3:19 pm
Hi, I just spotted this caterpillar this morning. I live in Eagle Point Oregon (southern oregon). I think it is maybe a western tiger swallowtail but am not sure due to the orange coloring.
Signature: Lara

Dear Lara,
Based on the caterpillar’s appearance, and your location, the only other possible species are the Pale Tiger Swallowtail and the Two-Tailed Swallowtail, so we turned to BugGuide where the comparison between two are described as:  “Larvae very similar to those of Pale Tiger Swallowtail, but black pupil of false eye-spot larger, and yellow spot inside eyespot entirely separated from it, not just notched.”  You may visually compare the difference in the eyespots by comparing this BugGuide image of the Caterpillar of a Western Tiger Swallowtail with this BugGuide image of the Caterpillar of a Pale Tiger Swallowtail Caterpillar, Papilio eurymedon.  Between the two, we are inclined to agree with you that this is the caterpillar of a Western Tiger Swallowtail, but we still haven’t considered the Two-Tailed Swallowtail.  The Two-Tailed Swallowtail Caterpillar is described on BugGuide as:  “Caterpillars resemble those of Eastern Tiger Swallowtail” which isn’t much help, nor is comparing your image to that of a Two-Tailed Swallowtail Caterpillar, Papilio multicaudatus, on BugGuide.  We have a very difficult time distinguishing between the species, so we are contacting Keith Wolfe for his opinion.  We are guessing it is a Two-Tailed Swallowtail Caterpillar based on image comparison of the eye spots.  One thing we can address is the orange color, which means your caterpillar is pre-pupal.  It has left its food source and is searching for a place to pupate.

Keith Wolfe Responds
Hello Lara and Daniel,
Caterpillars of the Pale, Two-tailed, and Western swallowtails are indeed difficult to distinguish by appearance alone, thus their somewhat differing preference of Oregonian hostplants — or in this case, shrubs/trees growing nearby — is probably the best indicator . . .
* Pale Swallowtail (Papilio eurymedon): Mainly various wild lilacs (Ceanothus).
* Two-tailed Swallowtail (Papilio multicaudata): Mostly wild cherries (Prunus), ash (Fraxinus), and hoptree (Ptelea).
* Western Tiger Swallowtail (Papilio rutulus): Many species of aspen and poplar (Populus), willow (Salix), and maple (Acer).
Hopefully the above isn’t too “scientific”.
Best wishes,
Keith

Lara Responds
Thank you.  Nearby to where I found it are Ash and Oak trees primarily.

Ed. Note:  Based on the information provided by Keith Wolfe and the response from Lara, we can speculate this is most likely the caterpillar of a Two-Tailed Swallowtail.

Letter 14 – Probably Chrysalis of a Tiger Swallowtail

Mysterious under-log chrysalis and clearwing sphinx
Location:  Southern Illinois
September 27, 2010 8:05 pm
Was out flipping over logs with the boyos today, and found this chrysalis on the underside of a log, surrounded by fungus, but apparently none the worse for the wear. Still wiggled when we teased it.
I’ve googled my first few guesses as to what forest butterfly it may belong to. Doesn’t seem to be a Mourning Cloak or a Comma. No particularly distinctive protrusions, and no metallic reflector bits. Found in open forest, under a log.
Does it look familiar to you?
Also attaching a clearwing sphinx shot that turned out well from the other week.
Signature:  Bert

Hi Bert,
We do not recognize this pupa, and we did a quick check on BugGuide, but did not have any luck.  We suspect this may be a moth pupa and not a butterfly pupa.  Perhaps one of our readers will be able to supply a response and identification.

Karl Identifies the Mystery Pupa
Hi Daniel and Bert:
I can’t be entirely certain but this looks very much like the overwintering pupa of an Eastern Tiger Swallowtail (Papilio glaucus). Swallowtail chrysalids are typically attached to a twig, branch or tree trunk by a silk girdle, but some species do pupate on the ground. Eastern Swallowtail caterpillars always chose a pupation site near the ground, and they quite often pupate on or among the leaf litter on the forest floor where the chrysalis is protected by its cryptic texture and coloration. In addition to the grey-brown coloration, characteristics include greenish patches of varying extent and intensity, two horns on the head and one horn at the top of the thorax. It looks to me as if all of these features are evident on this individual. How it got under the log remains a bit of a mystery, but I suppose the caterpillar could have crawled under it, or perhaps the chrysalis somehow rolled under. Anyway, that is my best guess. Regards.  Karl

Thank you Karl,
It appears you have identified yet another mystery for us.

Letter 15 – Pale Swallowtail

swallowtail and buckeye, paso robles

Ed. Note: Our dear friend Clare Marter Kenyon just sent these photos because she knew Daniel was preparing a powerpoint presentation for the Theodore Payne Foundation and he didn’t have many photos of the Western Tiger Swallowtail despite the countless individuals that flit around his Mt Washington garden in the summer.

Correction:  January 15, 2012
Thanks to input from lepidopterist Julian Donahue and Clare Marter Kenyon who took the photo, we have corrected this identification as a Pale Swallowtail, Papilio eurymedon, which may also be viewed on BugGuide.