Eastern vs Western Giant Swallowtail: Comparing the Two Butterflies

Swallowtail butterflies are known for their striking colors and large size, making them a delight for anyone to observe. Among these captivating creatures, two notable species are the Eastern Giant Swallowtail (Papilio cresphontes) and the Western Giant Swallowtail (Papilio oregonius).

The Eastern Giant Swallowtail can be found throughout the eastern United States and even in parts of Mexico, while the Western Giant Swallowtail, also known as the Oregon Swallowtail, is primarily found in the Northwestern United States. Both species display stunning color patterns on their wings, showcasing a combination of black, yellow, red, and blue.

Despite their similarities, subtle differences exist between the Eastern and the Western Giant Swallowtail. For instance, the yellow wing markings of the Oregon Swallowtail are brighter than the Eastern counterpart, setting them apart visually. Additionally, their habitats and preferred host plants for their caterpillars may vary, with the Eastern species being more prevalent in regions with citrus trees. Comparing these captivating species can provide a deeper understanding and appreciation for the world of Swallowtail butterflies.

Eastern and Western Giant Swallowtail Butterflies

Scientific Classification

Eastern Giant Swallowtail (Papilio cresphontes) and Western Tiger Swallowtail (Papilio rutulus) butterflies belong to the order Lepidoptera and family Papilionidae. Here’s a brief comparison of their classification:

Physical Characteristics

Giant Swallowtail and Western Tiger Swallowtail butterflies possess notable physical features:

• Eastern Giant Swallowtail: Black wings with yellow bands forming an “X” shape across the wingspan. Full wingspans range from 100 to 160 mm. Female butterflies typically larger with bluer hindwings.
• Western Tiger Swallowtail: Yellow wings with black stripes, resembling tiger fur pattern. Wingspans range from 70 to 100 mm.

Lifecycle

Eastern Giant Swallowtail

• Females lay eggs on citrus trees, prickly ash, and common rue.
• Eggs hatch in about 10 days.
• Caterpillars last around 3-4 weeks.
• Adult lifespan: 1-2 weeks.

Western Tiger Swallowtail

• Females lay eggs on tree leaves.
• Eggs hatch in about a week.
• Caterpillars last around 4-6 weeks.
• Adult lifespan: about 3 weeks.

Habitat

Giant Swallowtail and Western Tiger Swallowtail butterflies prefer differing habitats:

• Eastern Giant Swallowtails: Commonly found in citrus groves, gardens, and woodland edges in the southeastern United States.
• Western Tiger Swallowtails: Generally inhabit riparian zones, woodlands, and gardens throughout the western United States.

Distribution and Range

Eastern Giant Swallowtail

The Eastern Giant Swallowtail has a wider range, predominantly found in the eastern regions of North America. Key areas include:

• United States: East of the Mississippi River and extending into the Great Plains states¹
• Mexico: Several states¹
• Jamaica and Cuba²

They are largely found in deciduous forests and wooded areas.

Western Giant Swallowtail

In comparison, the Western Giant Swallowtail has a more limited distribution, primarily in specific regions:

• United States: Florida³ and Arizona⁴
• Mexico: Southern areas³

Their habitats usually include woods and areas with citrus host plants.

Comparison Table

Host Plants and Nectar Sources

Citrus

The giant swallowtail butterfly, specifically the Eastern and Western species, belong to the family Papilionidae and are commonly found in citrus orchards. Their host plants mainly come from the Rutaceae family, such as sweet orange (citrus × sinensis), lime, and other citrus plants. These plants serve as a vital food source for the larvae, also known as orange puppies¹. Here are some common citrus host plants:

• Sweet Orange (Citrus × sinensis)
• Lime
• Hoptree (Ptelea trifoliata)

In addition to these host plants, nectar plants like Lantana, Bougainvilla, and Lonicera japonica attract both species of giant swallowtails by providing nectar as an adult food source².

Non-Citrus

Giant swallowtails can also utilize non-citrus host plants, particularly species within the Zanthoxylum genus such as³:

• Gasplant (Zanthoxylum fagara)
• Hercules club (Zanthoxylum clava-herculis)
• Prickly Ash (Zanthoxylum americanum Mill)
• Lime pricklyash (Zanthoxylum clava-herculis)

These plants, while not citrus, still belong to the Rutaceae family and serve as essential host plants for both Eastern and Western giant swallowtails. Nectar sources for non-citrus host plants also include Solidago (goldenrods), Milkweed, and Amyris elemifera⁴.

Comparison Table

In summary, both Eastern and Western giant swallowtails have evolved to utilize a variety of host plants and nectar sources, mainly within the Rutaceae family. While citrus plants are essential hosts for these butterflies, they also thrive on non-citrus plants, allowing them to adapt and survive in various environments⁵.

Development and Adaptations

Larval Instars and Chrysalis

Eastern and Western Giant Swallowtails go through five larval instars before transforming into a chrysalis. Key differences include:

• Eastern Giant Swallowtail:

  • Larger in size
  • Chrysalis color: green or brown, resembling a twig

• Western Giant Swallowtail:

  • Smaller in size
  • Chrysalis color: mainly brown, resembling dry leaves

Caterpillar and Bird Droppings Mimicry

Both Eastern and Western Giant Swallowtails show amazing adaptations for survival. Young caterpillars resemble bird droppings, which helps in deceiving predators. As they mature, coloration and shape changes along with their instars.

Osmeterium and Setae

Apart from visual mimicry, caterpillars have an osmeterium, a fleshy appendage that emits a foul-smelling substance when threatened. This helps deter predators from eating them.

In summary, Eastern and Western Giant Swallowtails show remarkable adaptations for survival, including bird droppings mimicry and the use of osmeterium and setae to deter predators. Their larvae undergo five instars before forming chrysalis, with differences in size, coloration, and bristle density.

Natural Enemies and Pests

Vertebrate Predators

Giant swallowtail butterflies, both eastern and western, face challenges from several vertebrate predators. Some common predators include:

• Birds, which feed on caterpillars and adult swallowtail butterflies
• Lizards and small mammals that prey on caterpillars

Unfortunately, these predators can be challenging for entrepreneurs involved in butterfly farming or conservation efforts, as they reduce the number of healthy, viable butterflies.

Parasitoids

Parasitoids are organisms that ultimately lead to the death of their host. In the case of giant swallowtails, these can include several species of wasps:

• Brachymeria robusta
• Pteromalus cassotis
• Pteromalus vanessae
• Lespesia rileyi

The wasps lay their eggs in swallowtail caterpillars, and the wasp larvae eventually kill their host, causing damage to the butterfly population.

Comparison Table

Pests

Giant swallowtails are also affected by common pests, such as mites and aphids, which can cause damage to their food sources. Caterpillar’s primary food plants include the leaves of various citrus trees.

Key Characteristics of Giant Swallowtails’ Pests:

• Mites: microscopic arachnids that cause damage to the leaves
• Aphids: small insects that feed on plant sap and weaken the plant

Prehistoric vertebrates are not directly affecting the current population of giant swallowtails, but their evolutionary past might have played a role in shaping their defenses against natural enemies and pests today.

Interaction with Humans

Citrus Industry and Pest Management

The Eastern and Western Giant Swallowtails, members of the Papilionidae family, have a significant impact on the citrus industry. Their caterpillars, known as Orange Dog, feed on citrus leaves, causing damage to citrus farms. Some key differences between the two species include:

Pest Management

• Biological Control: Natural enemies, such as wasps and flies, help control the population of caterpillars.
• Cultural practices: Removing host plants reduces the appeal of citrus farms to the swallowtail species.
• Chemical control: Pesticides can be judiciously used to protect the citrus plants.

Conservation and Entomology

Both Eastern and Western Giant Swallowtails are essential in the field of entomology, as they are indicators of environmental health. Studying these butterflies helps scientists to understand factors that affect their populations, such as climate change and habitat fragmentation. Some measures to protect and conserve the Giant Swallowtails are:

• Creating butterfly gardens with preferred host and nectar plants for the respective species
• Avoiding the use of pesticides in home gardens, promoting a more butterfly-friendly environment
• Supporting research and conservation efforts by reporting swallowtail sightings to local naturalist groups

Species Comparison

Similar Swallowtail Species

Several swallowtail species share similar features with the Eastern Giant Swallowtail (Papilio cresphontes) and Western Giant Swallowtail (Papilio rumiko). Some of these species include:

• Polydamus Swallowtail
• Black Swallowtail
• Spicebush Swallowtail
• Pipevine Swallowtail
• Anise Swallowtail
• Zebra Swallowtail
• Two-Tailed Swallowtail
• Palamedes Swallowtail

These species are often found in similar habitats and sometimes have overlapping ranges.

Differences Between Eastern and Western Giant Swallowtails

While the Eastern and Western Giant Swallowtails are both large and vibrant species, they have some differences in appearance and behavior.

Appearance:

• Eastern Giant Swallowtails have a wider wingspan, reaching up to 6 inches, while Western Giant Swallowtails have a slightly smaller wingspan, usually around 5 inches.
• Female Black Swallowtails, closely related to the Eastern Giant Swallowtail, have larger hind wings with more blue pigmentation compared to their male counterparts.
• The Western Giant Swallowtail has a lighter yellow coloration on its wings than the Eastern Giant Swallowtail, which has a deeper, more saturated yellow color.

Behavior:

• Eastern Giant Swallowtails prefer to lay their eggs on plants from the citrus and rutaceae families, such as Ptelea trifoliata, while Western Giant Swallowtails are less specific and lay eggs on different host plants, including some non-native species.

By understanding the differences and similarities between the Eastern and Western Giant Swallowtails, one can better appreciate and identify these distinct and beautiful species.

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 – Courting Giant Swallowtails

Subject: Courting Butterflies
Location: Coryell County, Texas
March 9, 2017 3:39 pm
Hello again! These two butterflies stayed near the autumn sage (Salvia greggi) for about thirty minutes. I think they are more of the Giant Swallowtails, quite worn. She (I think) was trying to nectar, and he (I think) was in dogged pursuit. She would fly up to the sky, fly low, fly all around, couldn’t shake him, or was it a courtship dance? I don’t know. Eventually she flew off without him while he was patrolling nearby, and he flew all around the house for a time, perhaps looking for her? I only saw him nectar once.
Cloudy, humid, and warm 65 degrees, with a light breeze
Thank you and best wishes!
Signature: Ellen

Dear Ellen,
We agree that these are courting Giant Swallowtails, and your submission has perfect timing.  We saw a our first Giant Swallowtail of the season nectaring on the lantana growing on the curb of our neighbor’s yard today, but we were running late for work and we did not have an opportunity to snap an image.  Your action images are gorgeous.

Thank you so much! Best wishes to you both. ?

Letter 2 – Giant Swallowtail

polka-dot wasp moth
Hi Bugman,
I found a polka-dot wasp moth caterpillars on my desert rose. Should I be concern? Also, I’ve attached a picture of a swallow tail taken outside my window.
joanna

Hi Joanna,
The caterpillars will eat the leaves and the leaves will grow back. Unless the plant is infested, we would leave the caterpillars. Your Giant Swallowtail is beautiful.

Letter 3 – Giant Swallowtail

Giant Swallowtail
Hi — I just adore your website! You probably have tons of Giant Swallowtail butterfly pics, but they are so gorgeous, I thought perhaps a couple more couldn’t hurt! LOL!
Susan Rockwell
SW Florida

Hi Susan,
We don’t get many adult images, but ew do get Giant Swallowtail Caterpillars, known as Orange Dogs.

Letter 4 – Giant Swallowtail

Unknown swallowtail butterfly?
Is this a giant swallowtail (Papilio cresphontes)? It was flying very quickly today, 21Sept08 at about 3 pm from phlox to phlox stopping briefly for a sip. It looked about as large as black swallowtail, but have never seen this one in my yard. I usually see Tiger ST on the phlox, especially this time of the year. Thanks,
Monarch Guy
Minneapolis MN

Hi Monarch Guy,
Your identification of the Giant Swallowtail is correct.  It looks like your specimen is quite battered, and perhaps rode north on hurricane winds.

Letter 5 – Giant Swallowtail

Giant Swallowtail?
September 2, 2009
Hello Bugman,
Thank you for your amazing site.
I have seen this butterfly visiting the flowers on the landana camara (I think the common name is “spanish flag”) bush in our yard. My husband finally managed to get a picture of him/her today (Sept 2).
I checked the markings in Kaufman’s guide, and I think it is a Giant Swallowtail. It has a 5-6 inch wingspan, and the underside of its body is all light yellow, with just the small black streak along the top.
Is it unusual to see one in Los Angeles? It seems we are a little out of its range on the map.
Thank you!
Moira (photo by Simon)
Los Angeles

Hi Moira,
According to the BioOne website:  “Beginning in the 1960s, the familiar giant swallowtail (Papilo cresphontes) expanded its range into southern California from the east. From 1996 through 2003, at least 23 giant swallowtails were seen at 13 locations in the northern portion of the Baja California Peninsula, representing the first records of this species in the Mexican state of Baja California.”  We saw our first Los Angeles specimen about six years ago at the Huntington Gardens, and for the past three or four years, we see them in our own Mount Washington garden beginning in August.  One was on the front porch yesterday.

Letter 6 – Giant Swallowtail

what kind of butterfly is this?
September 19, 2009
my son took this wonerful picture of this butterfly in our backyard flower garden. i have never seen a butterfly like this one. maybe you could tell me what kind she is and how we can keep her coming back…
thanks, katy pierce
shreveport, louisiana

Hi Katy,
This is a Giant Swallowtail, Papilio cresphontes.  In our Los Angeles garden, this species takes nectar from lantana.  It is only in the past ten years that the Giant Swallowtail has expanded its range to include Los Angeles.  The caterpillars, known as Orange Dogs, feed on the leaves of citrus trees, so having a larval food source in your yard will help ensure that the adult butterflies will also be present.  According to BugGuide, the caterpillars also feed on the leaves of common pricklyash and common hoptree.  Since the species is native to North America, those plants were the original foods prior to the introduction of citrus.  With the cultivation of citrus trees in the warmer parts of the west, the range of the butterfly has expanded.

Letter 7 – Giant Swallowtail

Big Baby Butterfly
May 25, 2010
I saw this guy when I was watering the flowers, he was so big and I could tell he just became a butterfly his wings were still drying. Hence why I was able to get a decent pic, since he couldnt fly that well/far. I was wondering what kind of butterfly this is, if I held him with wings spread he would be about the size of my hand. Plus I was able to take a good pic of a great specimen and thought I would share with ya’ll.
Caitlyn in Austin
Leander, Tx

Hi Caitlyn,
This beauty is a Giant Swallowtail, and the caterpillars, which feed upon the leaves of citrus trees and resemble bird droppings, are called Orange Dogs.  The Giant Swallowtail is a native species and citrus is not.  Prior to the introduction of citrus trees to North America, the caterpillars of the Giant Swallowtail fed upon native trees including Common Pricklyash and Common Hoptree.  With the introduction of citrus, the range of the Giant Swallowtail has greatly increased to include Arizona and California.

Letter 8 – Giant Swallowtail

what kind of swallowtail?
Location:  Bath Michigan
August 8, 2010 6:38 am
Can you tell me what kind of swallowtail this is we live in Bath Michigan I can only seem to find a Thoas picture on web that looks close. There is so much brown on it i cannot identify it. Any help would be great thank you!
Holly VanVoorhis

Hi Holly,
The Thoas Swallowtail, Papilio thoas, has a much more southern range than Michigan, and it closely resembles the Giant Swallowtail, Papilio cresphontes, that has been reported from as far north as Canada, so we believe your individual is a Giant Swallowtail.  Interestingly, BugGuide devotes an entire page to distinguishing the two species.  The undersides of the wings of both species are typically much lighter than is evidenced in your photo, but this might be partially because of the lighting, the angle of the photo, or possibly because your individual is an older specimen.  Though we were troubled by this coloration, we did locate an image on BugGuide that looks quite similar to your individual.  You may read more about the Giant Swallowtail on the BugGuide information page.

Letter 9 – Giant Swallowtail

Our first sighting of the Great Swallowtail, I think
Location:  Clearwater, Florida
August 25, 2010 6:39 pm
This butterfly visited our papaya flowers last week and posed so beautifully, I had to take its photo. At first I thought it was a Schaus butterfly but the book I looked into said no.
Linda from Organic Living

Hi Linda,
You have photographed the largest butterfly in North America, the Giant Swallowtail, Papolio cresphontes, which you may learn about on BugGuide.  To get a better idea of the subtly beautiful markings on the Giant Swallowtail’s wings, see this BugGuide image.

Letter 10 – Giant Swallowtail

Giant Swallowtail?
Location:  Jacksonville FL
September 8, 2010 1:28 pm
I was wondering is you could ID this lovely butteryfly. I think it might be a Giant Swallowtail judging by photos I’ve seen here.
I love this website and I use it frequently. I hope you share more photos with you.
Thanks!
Signature:  Dan

Dear Dan,
Thank you for the compliment.  We are very excited to post your photograph.  Just two days ago, Daniel saw a Giant Swallowtail fluttering on the neighbor’s plumbago at our Mt Washington, Los Angeles offices, but he didn’t get the camera.  Your photo of a Giant Swallowtail will fill the void.

Letter 11 – Giant Swallowtail

Giant Swallowtail
Location:  Irvine, California
September 14, 2010 6:10 pm
This huge butterfly spent some time in my garden today. After spending way too much time on the internet trying to identify it, I happened upon your website! Fabulous! My visitor was a Giant Swallowtail Butterfly.
Signature:  MsMarvel

Dear MsMarvel,
We love hearing accounts of people being able to self identify their insects using our website the way you were successful at identifying this Giant Swallowtail, the largest butterfly in North America.

Letter 12 – Giant Swallowtail

Papilio (Heraclides) thoas autocles ?
Location: Long Beach, California
May 20, 2011 6:51 pm
Hi.
This is little flew into my garden today, and I found him on the ground. I’m not sure if he is passing away or if he is injured. I’m also unsure if I should try to feed him or how to help him in anyway.
Signature: Sarah

Hi Sarah,
We actually believe this is the very similar looking Giant Swallowtail, Papilio cresphontes, which you may find on BugGuide.  We wonder what calamity befell this lovely creature.

Do you know why he would be in my area? I live in Long Beach, California near Cypress or Seal Beach….. I’ve been checking on he religiously to see for any movement. He doesn’t move around or anything much but at times I will see one of his legs move, a little bit though. I know they need sunlight for energy, would it be better to keep him inside? Then tomorrow move into sun ? Is there anything I can do for him ? I put leaves and some dryer fluff in the container hoping to keep him warm. The problem is my mom is deathly afraid of butterflies, and moths……
Please any information given will help me. I am not sure if I should find someone who specializes in butterflies or ?!?!?
Sincerely,
Sarah

The Giant Swallowtail has naturalized in the Southern California area.  Sorry, but we can’t offer any resuscitation advice.  Butterflies are not especially long lived insects, though Swallowtails should survive several months.  We suspect, as we mentioned earlier, that this individual met with some calamity.  Its wings are in magnificent form to be an older individual.

Letter 13 – Giant Swallowtail

geometric pattern swallowtail
Location: Eau Claire, Wi.
August 8, 2011 8:13 pm
I know now that this is a black swallowtail. But LOOK at the pattern on this baby! My eye was drawn to it as soon as I stepped outside. Never have I seen one of these before. It was very big too. Spotted and photographed in Eau Claire Wi. on Aug 8, 2011 at 1:00 pm.
Signature: gail from Wisconsin

Hi Gail,
This is a Giant Swallowtail, not a Black Swallowtail.  It is reported to be the largest North American butterfly.

Letter 14 – Giant Swallowtail

Papilio cresphontes, Giant Swallowtail?
Location: Hawthorne, CA
October 12, 2011 3:11 pm
Hi again,
I also had a chance this morning to get some pictures of what I think is a Giant Swallowtail. Am I correct? Do you know how to tell if this male or female?
Signature: Thanks, Anna Carreon

Good Morning Anna,
Your photos are making us jealous that we need to go to work during the week and we are missing the opportunity to enjoy our own garden during these glorious Southern California fall days.  This is indeed a Giant Swallowtail.  To the best of our knowledge, there is no easy way to distinguish males from females.  That might require examination of the genitalia.

Hi Daniel,
I just remembered that I read somewhere that the male of this species tends to flutter it’s wings when feeding, so that may be a way to tell the difference between male & female.
Anna

It is difficult to see a flutter in a still photograph though.

Hi Daniel,
It’s wings were indeed fluttering.  I remember wondering if I would get a good photo.
Anna

Letter 15 – Giant Swallowtail

Subject:  Giant Swallowtail Ovipositing?
Location: Hawthorne, California
September 23, 2012 2:37 pm
Hello,
While the first photo is not focused very well, I included it anyway to show it is a giant swallowtail. Do the next two show it ovipositing on the cigar plant bush? There is a lime tree very near by.
Signature: Thanks, Anna Carreon

Hi Anna,
Before we could provide you with an accurate answer, we needed to look up the plant family for the cigar plant.  According to Floridata, the cigar plant is in the Loosestrife Family Lythraceae.  Prior to the introduction of citrus in North America, the native Giant Swallowtails used “Common Pricklyash (Zanthoxylum americanum), and Common Hoptree (Ptelea trifoliata)” as larval foods, according to BugGuide.  We do not believe the Giant Swallowtail in your photo is ovipositing on the cigar plant, but we may be wrong.

Letter 16 – Giant Swallowtail

Subject: Beauty! Is it a Giant Swallowtail?
Location: Coryell County, central Texas
March 18, 2013 2:52 pm
This beautiful, large swallowtail was in constant motion. Is it a Giant Swallowtail (Papilio cresphontes)? Photo taken today, warm weather at 80 degrees. I think the plant is Purple Verbena. Thank you!
Signature: Ellen

Hi Again Ellen,
You are correct that this is a Giant Swallowtail, and they truly are beautiful butterflies.

Letter 17 – Giant Swallowtail and Monarch

Subject: Is this a Giant Swallowtail?
Location: Fullerton (Orange County) CA
July 31, 2014 8:20 am
Hello;
Here is a better photo of our overnight visitor. It landed on the night blooming jasmine at dusk yesterday and settled in for the night. To my surprise it is still there as of 8 a.m. It is quite large, at about 4″ across, warm black with striking yellow markings. When viewing from the kitchen window slightly above, there is a thin edge of yellow showing on the ‘shoulders’ so that it presents as a heart. It’s beautiful. Thank you for your wonderful website.
Signature: Likes Bugs

Dear Likes Bugs,
You are correct that this is a Giant Swallowtail, a relatively recent resident of Southern California.  The Giant Swallowtail is native to the eastern portion of North America, but the caterpillars, known as Orange Dogs, adapted to feeding on the leaves of orange and other citrus trees, and as the cultivation of citrus spread west, the range of the Giant Swallowtail followed.  We believe they first appeared in Los Angeles in the 1990s.  According to the Los Angeles Times:  “The giant swallowtail butterfly, Heraclides (Papilio) cresphontes, is native to the Southeast. Since the 1960s, populations have spread west following a corridor of suburban development and the species’ favorite larval food source — citrus — through Arizona, into the Imperial Valley, then San Diego and north to Orange and Los Angeles counties. They’ve been sighted as far north as Santa Barbara and Bakersfield.  Numbers have surged since 2000, says Jess Morton, president of the Palos Verdes-South Bay chapter of the Audubon Society. Members have held a butterfly count at the same location, on the first Sunday in July, every year since 1991. According to their records, a single giant swallowtail was first seen in the South Bay in 2000. They counted 23 in 2007.”  According to the Kaufman Field Guide to Insects:  “Ranges throughout most of the east;  more limited distribution in the southwest, but has expanded into the Los Angeles basin within the past 20 years.”

Thank you so much Daniel. We have two tangerine trees, a lemon, a grapefruit, a valencia orange, and two washington navel oranges on our 8,500 sf lot. So yes, there is lots of citrus here for the larvae.
I found it so interesting that it settled on the leaves, spread it’s wings and went to sleep. It took off when the sun hit it at about 9a this morning. It is the first of that kind I’ve seen here (northern inland hilly Orange County – warmer than the coast.)
The Monarchs on the other hand, are plentiful. We have many milkweed plants for them and they put on a show – photo attached.
Thank you again for your help!
Nancy Rennie

Hi again Nancy,
It is our observation that Monarchs seem more plentiful this year than they have in recent years.

Letter 18 – Giant Swallowtail

Subject: Giant Swallowtail?
Location: Coryell County, Texas
August 31, 2014 9:18 pm
Hello,
This gorgeous creature visited our Vincas while we were gardening today. Is it a Giant Swallowtail, Papilio cresphontes? Today was hot and sunny, mid 90’s.
Thank you!
Signature: Ellen

Hi Ellen,
You are correct that this is a Giant Swallowtail, and we see that you also submitted some images of a Giant Swallowtail in spring 2013.  About seven years ago, we started to notice Giant Swallowtails nectaring on lantana in our garden.  We planted some citrus trees around that time, and this year we have noticed a Giant Swallowtail very interested in the Grapfruit Tree, so we expect if we searched carefully, we might locate some Orange Dogs.

Letter 19 – Giant Swallowtail

Subject: Great Swallowtail
Location: Coryell County, Texas
October 12, 2016 1:27 pm
Hello again! I thought you might like to see this Great Swallowtail, photographed through the window as it visited a hanging basket of Portulaca flowers today. (Used auto-correct for the photos as they had a haze.) Of course the butterfly flew off as I s-l-o-w-l-y opened the door, as always. 😀
Hope you are both well.
Signature: Ellen

Good Morning Ellen,
Thanks so much for sending us a new image of a Giant Swallowtail, not a Great Swallowtail, which to the best of our knowledge is not a recognized common name.

October 12, 2016 1:34 pm
I’m so sorry, I meant to write Giant Swallowtail. I think it’s a Giant Swallowtail as you’ve very kindly identified them for me before. Hope you’re having a great week! Thank you
Signature: Ellen

Update:  October 16, 2016
Subject: More Giant Swallowtails
Location: Coryell County, Texas
October 16, 2016 3:00 pm
I’ve never seen as many Giant Swallowtails near our house as I have this month. We did have some summer rain, which is unusual, so their host plants may be thriving. The pictured plants are natives, Texas Rock Rose (Pavonia lasiopetala) and Autumn Sage (Salvia greggii). I’m not sure if these are of the same individual butterfly. The swallowtails seem to be patrolling the gardens.
Signature: Ellen

Dear Ellen,
Thanks for the update on your Giant Swallowtail sightings.  That head on view of the Giant Swallowtail flying towards the camera is amazing.

Letter 20 – Female Giant Swallowtail

Mexican Swallowtail – Giant Swallowtail or Thoas Swallowtail?
hi Bugman!
I wrote a few weeks ago after I found a caterpillar I could not identify. I gave it a habitat and let it do it’s thing. I came home to a beautiful swallowtail yesterday! I originially thought it was an ‘orange dog’ caterpillar — but it wasn’t quite the right colors.

Then I found a Mexican website (I live in Tucson Arizona) and was able to see it was some sort of swallowtail larva. I have attached a photo sequence of caterpillar, to chrysallis, to butterfly.

It’s happily fluttering about my yard now, but I think I got some good pics while it was in my care. This time I sent web-ready versions if you want to post them. I’m having trouble determining if it’s Giant Swallowtail or Thoas Swallowtail. See:
http://www.mariposasmexicanas.com/papilio_heraclides_cresphontes.htm
and http://www.mariposasmexicanas.com/papilio_heraclides_thoas_autocles.htm
I cannot really determine (even by Googling) if the lower wing red markings are classic of either species since my swallowtail has more red going up the lower wing. Either way, it seemed to be a mexican variety (sandy coloring) of the usual dark brown/white orange dog caterpillar. I love your site! You got me hooked and trying to identify this critter! Thanks!
Adrienne

Hi Adrienne,
Thanks for all the photos and research. According to BugGuide: The Giant Swallowtail is “Distinguished from P. thoas by the larger spots forming in the lower left leg of the X on the front wing. ” Your specimen has small spots on the forewings, so we favor Thoas Swallowtail. Here is just one more link with information.