What Do Swallowtail Caterpillars Eat? A Friendly Guide to Their Diet

Swallowtail caterpillars are fascinating creatures that play a vital role in the life cycle of swallowtail butterflies. As the larval stage of these butterflies, their main job is to consume as much food as possible to prepare for their eventual transformation.

You might be curious about the diet of these caterpillars. These voracious eaters usually feed on specific host plants that cater to their dietary needs. For example, the spicebush swallowtail feeds on the leaves of spicebush and sassafras trees.

By understanding the eating habits of swallowtail caterpillars, you can appreciate the role they play in nature and perhaps even help create a friendly environment for them to thrive in your garden, fostering a healthy population of swallowtail butterflies.

Swallowtail Caterpillar Identification

Characteristic Features

Swallowtail caterpillars have some distinct features that can help you identify them easily:

  • They can be found in various shades of green with black bands on each body segment
  • The black bands are interrupted by yellow-orange dots 1
  • They can reach up to 2 inches in length 1

For example, the Black Swallowtail Caterpillar (also known as parsleyworm) has these characteristics and feeds on plants in the carrot family (Apiaceae). Another related species, the Eastern Black Swallowtail Caterpillar, has similar features and can also be found feeding on plants in the carrot family.

Range and Habitat

Swallowtail caterpillars are known to inhabit a variety of environments, including:

  • Meadows
  • Prairies
  • Parks
  • Wetlands
  • Sunny backyards 2

For example, Eastern Tiger Swallowtails and Spicebush Swallowtails can almost always be found in Kentucky forests during the spring and summer 3. The Eastern Black Swallowtail Caterpillar has a natural range that includes the eastern United States and parts of Mexico 4.

Species Variation

When identifying Swallowtail Caterpillars, it is essential to recognize that there are different species with subtle variations in their characteristics. Here are some distinguishing features of two well-known species:

Species Forewing Color Hindwing Color Notable Features
Black Swallowtail Caterpillar Black with yellow Black with blue, orange Yellow-orange dots on black bands 1
Eastern Tiger Swallowtail Black with white Black with blue, orange Two orange spots and faded row of white spots 5

By understanding these variations, you can correctly identify Swallowtail Caterpillars and learn about their preferred habitats and diets.

Swallowtail Caterpillars’ Diet

Swallowtail caterpillars are known for their diverse diet. They mainly feed on the leaves of various plants, such as parsley, dill, fennel, and carrot. Your garden might attract these caterpillars if you have these herbs. They also feed on native trees and shrubs like tulip tree, black cherry, and magnolia.

Some species of swallowtail caterpillars have specific host plants. For example, the Spicebush Swallowtail prefers spicebush and sassafras leaves, while the Tiger Swallowtail enjoys aspens, birches, and willows. Knowing their preference can help you create a friendly habitat or choose plants wisely.

Here’s a table comparing the diets of different Swallowtail caterpillars:

Swallowtail Species Host Plants
Spicebush Swallowtail Spicebush, Sassafras
Eastern Tiger Swallowtail Aspens, Birches, Willows
Black Swallowtail Parsley, Dill, Fennel, Carrots

As adult butterflies, swallowtails feed on nectar from various flowers, like milkweed, thistle, lilac, zinnias, and phlox. Including these plants in your garden can attract both caterpillars and butterflies. Be aware of the osmeterium, a defensive organ they use when threatened. It releases an unpleasant smell that deters predators.

In conclusion, swallowtail caterpillars have diverse diets depending on their species. They mainly feed on leaves of herbs, trees, and shrubs, with varying preferences. As butterflies, they enjoy nectar from various flowers. Providing a mix of host plants and nectar sources in your garden will invite these beautiful creatures to visit and thrive.

Swallowtail Caterpillars’ Life Cycle

Stages in Life Cycle

Swallowtail caterpillars, like many insects, go through a complete metamorphosis during their life cycle. They start as eggs laid on the underside of leaves, typically on their favorite host plants. For instance, the California Pipevine Swallowtail lays its eggs on the pipevine plant. After hatching, the caterpillars feed on leaves, growing and developing into the next stage known as larva.

During the larval stage, caterpillars of different swallowtail species have distinct appearances. For example, Black Swallowtail caterpillars feed on plants in the carrot family and have green bodies with black bands and yellow-orange dots.

Once they’ve reached the right size, caterpillars enter the pupa stage, where they form a chrysalis. Inside the chrysalis, the caterpillar undergoes massive cellular changes, transforming into an adult butterfly. When they’re ready, the adult butterfly will emerge from the chrysalis and spread its wings, ready to continue the life cycle by mating and laying eggs.

Molting Process

As swallowtail caterpillars grow, they go through several molt stages, which allow them to expand in size. During molting, the caterpillars shed their old exoskeleton, revealing the soft, larger exoskeleton underneath. They will harden the new exoskeleton and continue feeding and growing until the next molting phase.

In the course of their relatively short lifespan, swallowtails may go through multiple generations in a single year. The specific number of generations depends on the climate and region where they’re located, but you can expect to see various stages of swallowtail caterpillars throughout the warmer months.

Defense Mechanisms and Predators

Self Defense

Swallowtail caterpillars have developed various tactics to protect themselves from potential dangers. For instance, black swallowtail caterpillars possess a unique feature called osmeterium. When they feel threatened, they release these forked glands that emit a foul odor, repelling predators.

To further enhance their self-defense, some swallowtail caterpillars display eye spots. These can confuse predators into thinking they’re dealing with a larger, more threatening creature.

Common Predators

Swallowtail caterpillars have several predators, including:

  • Spiders: These arachnids often ambush unsuspecting caterpillars, using their venom to immobilize their prey.
  • Birds: Many species of birds love to snack on caterpillars, picking them off leaves or branches.

In conclusion, swallowtail caterpillars have evolved a variety of defense mechanisms to keep predators at bay. Their unique eye spots and odorous osmeterium help them survive and eventually transform into beautiful butterflies.

Planting for Swallowtail Caterpillars

Host Plants for Different Swallowtail Caterpillars

Swallowtail caterpillars have various host plants based on their species. For instance, Pipevine Swallowtails mostly feed on Pipevine plants, while the Spicebush Swallowtails prefer plants like aspens, birches, and willows.

Black Swallowtail caterpillars are often found eating leaves and flowers of plants in the carrot family, such as carrot, parsley, dill, and fennel.

When planting for Giant Swallowtails, consider species like wild black cherry, sweet bay magnolia, and citrus trees, that are known to attract them. Sweet bay magnolia and redbud are native trees that provide sustenance to many swallowtail species.

Swallowtail Species Host Plants
Pipevine Pipevine plants
Spicebush Aspens, Birches, Willows
Black Swallowtail Carrot, Parsley, Dill, Fennel
Giant Swallowtail Wild Black Cherry, Sweet Bay Magnolia, Citrus Trees

Planting Tips

  • Choose native plants that support swallowtail caterpillars.
  • Include a variety of host plants to attract different swallowtail species.
  • Plant trees and shrubs like tulip trees (Liriodendron tulipifera), wild black cherry (Prunus serotina), and magnolia virginiana to diversify your garden.

Remember, planting a variety of these host plants in your garden will encourage swallowtail caterpillars to thrive. Happy gardening!

Swallowtail Caterpillar Rearing

Swallowtail caterpillars are the larvae of various species of swallowtail butterflies. To help rear these caterpillars, it’s important to know their dietary preferences and create a suitable enclosure for their growth and development.

They mainly feed on plants from the Apiaceae family, such as dill, parsley, and fennel. Some species, like the Eastern Black Swallowtail, are often found munching on herbs in your garden. Others, like the Pipevine Swallowtail, prefer Pipevine plants, which are toxic and offer protection from predators. Additionally, the Spicebush Swallowtail is known to feed on the leaves of spicebush plants.

Creating a proper enclosure for your caterpillars involves providing adequate food sources along with a clean and safe environment. Keep an eye out for signs of ill health, which could include lack of appetite, lethargy, or discolored frass (caterpillar droppings).

To compare the dietary preferences and habitats of different swallowtail species, consider the following table:

Swallowtail Species Host Plant Habitat
Eastern Black Swallowtail Dill, parsley, fennel Gardens with herbs
Pipevine Swallowtail Pipevine Eastern North America
Spicebush Swallowtail Spicebush plants Forests and gardens

Remember to:

  • Provide the appropriate host plants for the species you’re rearing
  • Maintain a clean and safe environment
  • Monitor the caterpillars for signs of ill health

By doing so, you’ll be able to rear healthy swallowtail caterpillars and help contribute to the preservation of these captivating butterfly species.


  1. Black swallowtail caterpillar (parsleyworm) | Arthropod Museum 2 3

  2. Black swallowtail, Papilio polyxenes – Wisconsin Horticulture

  3. Swallowtails of Kentucky – University of Kentucky Entomology

  4. Eastern Tiger Swallowtail – US Forest Service

  5. Spicebush Swallowtail | NC State Extension Publications

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 – Swallowtail Caterpillar India: Common Mormon


this creature on my lime tree
Location: india
September 23, 2011 2:55 am
Have found a few of these on my lime tree and i am told they chew up all the leaves. but since i dont know their name, i am unable to address the problem.
please help
Signature: Sukhie

Common Mormon Caterpillar

Dear Sukhie,
This is the caterpillar of a Swallowtail Butterfly, and unless the tree is totally defoliated, which we doubt will happen, the loss of a few leaves to feed this caterpillar is a small sacrifice to be able to enjoy the lovely adults flitting around the garden.  The red structure is a defense organ known as an osmetrium, and in addition to resembling the tongue of a snake, the caterpillar is able to give off a strong scent that dissuades predators.  We did a bit of research and we have learned that your caterpillar is
Papilio demoleus malayanus, and it is commonly called the Lime Butterfly.  We searched the internet and found many photos of the caterpillar, but your photo is probably one of the best.  We are proud to include it on our website.  You can see the entire life cycle of this lovely species on the Butterflies of Singapore website.

Thank you for your prompt reply, have plenty other pictures of this caterpillar as well. Have removed the from my young trees and placed them elsewhere. Love them butterflies.

Make sure you place them on lime or other citrus if you want them to survive.

Correction Courtesy of Keith Wolfe
Hello Daniel and Sukhie,
Knowing that your time to do Internet searches is very limited, Daniel, please allow me to correct the caterpillar ID to that of the COMMON MORMON (Papilio polytes).  I’ve seen hundreds of Lime Butterfly and Common Mormon larvae all across Asia, the two being easily separable by a coffee-colored band between the “eyes” (Lime Butterfly) and prominent blue spots on the head and body (Common Mormon).  FYI on a simple comparative Word doc that I posted several years ago on an Indian forum — http://groups.google.com/group/butterfly_india/msg/405238f507d08e91.
Best wishes,


Letter 2 – Swallowtail Butterfly from South Africa: African Citrus Swallowtail


Hi There,
My friend found this moth inside his apartment in Cape Town, South Africa. What Kind of moth is it? Regards,
Angela Gerber

Hi Angela
This is not a moth. It is a Swallowtail Butterfly. We do not know the exact species, but we are confident that one of our readers, who is not currently late for work, might have time to do the necessary web research and then provide us with the species name and a link to the identification.

Though not an expert, I believe that is a butterfly of the species Scientific Name: Papilio demoleus. The common name will vary from region to region. Some common names are Citrus Swallowtail; Lime Swallowtail; Lemon Swallowtail; Chequered Swallowtail; Orange Dog and Christmas Butterfly. Here are two source for confirmation: http://www.nic.funet.fi/pub/sci/bio/life/insecta/lepidoptera/ditrysia/papilionoidea/papilionidae/papilioninae/papilio/index.html#demoleus and http://en.wikipedia.org/wiki/Papilio_demoleus Hope I’m correct. cheers

Guilty as charged! It’s the Citrus Swallowtail butterfly, Papilio demodocus. Take a look at http://www.bushveld.co.za/pictures-of-citrus-swallowtail.htm Best,

A follow-up:
When I saw the P. demoleus Linnaeus pictures (the Lime or Lemon Swallowtail), which appear to be identical to the images I found of P. demodocus Esper, I thought maybe P. demodocus was just a synonym. However, when I researched a bit further, I see that P. demoleus and P. demodocus are sister species! Throughout Africa, the butterfly that looks like this is P. demodocus, the African Citrus Swallowtail a.k.a. African Lime Swallowtail. P. demoleus, a very similar species of citrus swallowtail, is very much more widespread globally, and is poised to become a serious pest threat to Florida citrus groves, if reaches the mainland from the Caribbean. Take a look at http://www.doacs.state.fl.us/pi/enpp/ento/limeswallowtail.html
And in that article they do also mention the African species, and the confusion with the common names: “In Africa, the related African lime swallowtail, Papilio demodocus Esper, is also called the citrus swallowtail.”
Susan J. Hewitt

Letter 3 – Swallowtail Caterpillar from Mexico


Subject: what caterpillar is this?
Location: Northeast Mexico
May 10, 2014 12:01 pm
Found this one trying to go up a wall for a while, put it on a branch of an avocado tree, stayed there for hours until dark, next morning it was up in the tree, shrunk already as in a cocoon. What type of butterfly will come out of it? Or is it a moth? Looks to me like some type of swallowtail?
Signature: Alex

Swallowtail Caterpillar
Swallowtail Caterpillar

Dear Alex,
You are correct in suspecting that this is a Swallowtail Caterpillar, but we have to research the species.  It is most likely typically pictured as a green caterpillar, as its orange coloration was an indication it was ready to undergo metamorphosis into a chrysalis.  Many Swallowtail Caterpillars turn orange or brown just prior to transformation.  We have several similar examples in our archives, and each time, the caterpillar was associated with avocado trees.  Keith Wolfe commented on one of the images:  “Yes, this wandering prepupa (compare its faded coloration to this caterpillar still feeding on an avocado leaf: http://www.flickr.com/photos/missingchandra/76362584/ ) will soon metamorphose into one of the 11 or so butterflies in the ” Pyrrhosticta ” group of Papilio swallowtails — P. cleotas ,P. garamas ,P. victorinus , etc.”  Here is a Keith Wolfe comment on a FlickR posting:  “This caterpillar will metamorphose into one of the ‘Pyrrhosticta’ group of
Papilio, subgenus Pterourus, swallowtails – almost certainly either Pa. garamas (Magnificent Swallowtail) or Pa. menatius (“Victorine” Swallowtail), depending upon which adult flies at that location. … also on avocado, a common hostplant of these two butterflies.”

Wow! Thank you Daniel,
Ill keep checking on it, hope to see it as a butterfly. I researched a bit and they stay there for two and a half months? What is weird is that its spring already so it will come out in the summer? It’s already pretty hot and should be getting worse… what I had read is that it was in a cocoon from fall to spring… could it just be a different variety? or is it just very late?

We don’t know the exact time spent in the chrysalis stage.  A cocoon is spun from silk, and this Swallowtail does not form a cocoon.  It has a bare pupa known as a chrysalis.  If you get an image of the adult butterfly, please send it to us.

Could it be that the buttefly came out already? I can’t find the chrysalis anymore (it did look more like a bare pupa as you say, i dont know why I didnt take a picture) and there was a beautiful black and bright blue swallowtail flying around the little garden for quite a while. It wouldnt stay still for a picture though! Too busy searching for food maybe? I ll keep checking if it comes back to get a decent picture, if not, I ll send what I got. Do you think it could be the butterfly from that caterpillar so fast? it formed the chrysalis saturday night…

In our opinion, metamorphosis would take longer than two days, even in a tropical climate since heat will speed up the process.

Yeah, that’s what I think now, plus it was exactly the butterfly from this link: http://nativeplantwildlifegarden.com/raising-eastern-black-swallowtail-caterpillars/ it did stay in the garden for hours flying around, would come back during the day, never got a great picture as it never stood still. I guess a pigeon or something must have eaten the other one as I can’t find it anymore…
I found a few other caterpillars that look more like those in that blog from that butterfly I did see. They are all on parsley. I ll send the pictures later…

The caterpillar in your image is NOT a Black Swallowtail Caterpillar.  As we stated previously quoting Keith Wolfe:  “This caterpillar will metamorphose into one of the ‘Pyrrhosticta’ group of Papilio, subgenus Pterourus, swallowtails – almost certainly either Pa. garamas (Magnificent Swallowtail) or Pa. menatius (“Victorine” Swallowtail), depending upon which adult flies at that location. … also on avocado, a common hostplant of these two butterflies.” 

Letter 4 – Swallowtail Caterpillars on Fennel


What kind of bug am I?
These caterpillars have eaten my Fennel Plant. Are they future butterflies?
Donna Magnuso

Hi Donna,
There are two very similar looking Swallowtail Butterfly Caterpillars with nearly identical food plants. The Anise Swallowtail, Papilio zelicaon, is found in the Western U.S. The Black Swallowtail, Papilio polyxenes, is found in the east. Depending upon your location, your caterpillar is one of these, though our guess is the Anise Swallowtail.

Letter 5 – Swallowtail Chrysalis


Subject: Very Odd Looking Cocoon
Location: San Diego
April 22, 2013 12:09 am
I found this cocoon on our fence. It is really weird, kind of creepy but also quite fascinating.
It is supported to the fence by two anchor lines. It is about 1.5 inches long. When I tap on the fence, its lower body flexes a little (I have video). I think it tries to disguise itself as a branch. I’m not sure if the face-like figure was actually a face or just a clever way to scare off predators. It has been there for over a month. Maybe two. Pictures were taken on the 7th and it was there for at least a week and it is now the 22nd and its still there.
Signature: BagToss.com

Swallowtail Chrysalis
Swallowtail Chrysalis

Dear BagToss.com,
A cocoon is spun, often of silk, and it protects the pupa of generally moths.  This is a bare pupa of a butterfly, known as a chrysalis.  The two anchor lines you mention are a silken girdle to support the chrysalis in an upright position, and this girdle is characteristic of a Swallowtail Chrysalis from the family Papilionidae.  We suspect there might be a citrus tree near your fence and that this is the Chrysalis of a Giant Swallowtail, though it might be another species in the family.  Here is a BugGuide photo of the Chrysalis of a Giant Swallowtail for comparison.

Thank you for the quick response.  We do have a nectarine tree within 6 feet of the cocoon.  I guess butterfly will emerge very soon based on this link: http://en.wikipedia.org/wiki/Papilio_cresphontes   I hope to see it in action.  What time of day do butterflies normally hatch?

Our guess is that butterflies are most likely to emerge in the morning, but we are not certain.

Letter 6 – Swallow-Tailed Moth from Sweden


Subject: Creme white orangestriped moth?
Location: Europe Sweden Skolstad http://goo.gl/maps/VzWR
July 12, 2012 8:18 am
Hi there an insect took a rest against the rain and thunder on my windows frame.
I would like to know what it´s called?
Thought it was a bit of masking tape that I´ve forgotten 😉
Signature: David

Swallow-Tailed Moth

Dear David,
This is such a lovely moth that we figured it would be relatively easy to identify, especially since we were quite certain it was classified in the family Geometridae.  We search through numerous images of Swedish and Northern European Moths with no luck, so we turned to the UK Moths website where we learned it is the Swallow-Tailed Moth,
Ourapteryx sambucaria.  Here is what UK Moths states:  “A spectacular species and one of our largest Geometrids, this is however reasonably common in Britain, except for northern Scotland where it is local or absent.  Being strictly nocturnal and having quite a short emergence period in July, it is not often encountered by the non-enthusiast.  The larvae feed on a number of trees and shrubs, but prefer ivy (Hedera helix).”  We then found photos on this Finnish website as well as on Lepidoptera.proGlobal Twitcher lists the Swedish name as Stjertmåler.  At least we believe that is a name.

Letter 7 – Swallowtail Butterfly Chrysalis


Pupa ID
Hello, Here in the wet Northwest, our family has been watching what appears to be a pupa for four months. It is attached to a small rosebush on our deck. Can anyone identify it? When can we expect a metamorphosis?
Keizer OR

Hi Elliot,
The silken girdle that keeps this chrysalis upright immediately identifies it as one of the Swallowtail Butterflies. Sorry, we cannot identify the exact species.

Letter 8 – Swallowtail Caterpillar from Mexico


This may be a caterpillar known as “cara de nino” in Central Mexico
Mon, Jun 1, 2009 at 5:28 AM
I have been trying to find out more about this insect for quite a while, but don’t even know where to start. I only saw one of them while living in Guadalajara, Mexico. I have been told that it is a caterpillar that pests avocado trees. It is, well, avocado green with darker lines zigzagging its oval-shape body. Its head is eerily round and shiny. Some say it has a forked, red tongue, which comes out of its mannequin-looking mouth. They are called “cara de nino” (baby face) bugs.
John Sanchez
Guadalajara, Mexico, for sure

Swallowtail Caterpillar
Swallowtail Caterpillar

Hi John,
This is some species of Swallowtail Caterpillar. Your photo does not have enough detail to allow for an exact species identification, but it is in the genus Papilio.

Update: Wed, Jun 3, 2009 at 8:15 PM
Hi Daniel,
Sometimes when I log in, type a comment, and then click “Post”, a message states that my words are awaiting approval. More often, like today, I see no such affirmation, which leads me to suspect that my two comments went into a black hole. Thus, I’m also sending them to you directly – hope that’s OK.

Hola John,
The answer can be found here (from Guatemala) . . .
. . . and here (more specifically, Veracruz):
Best wishes,
Keith Wolfe

Letter 9 – Swallowtail Caterpillar, but which one??? Answer: Two Tailed Swallowtail


Awaiting Papilio rutulus or Papilio multicaudata?
Sat, Apr 11, 2009 at 7:14 PM
I tried sending these through the website but it kept failing. Hope this is OK.
We here in Montana have been long awaiting the arrival of some overwintering Papilio/Swallowtails in our garage. Try as we might, we have not been able to determine if our caterpillars were Two-tailed or Western Tiger Swallowtails. The difference will determine if they should emerge in late May or late June (around here.) We have been waiting so patiently, it would be such a shame for us to mess up the timing now. (The garage stays so cold we will probably have to move them to get them to emerge.) We have some great photos of several different caterpillar stages as well as the pupae. Attached are a few. These caterpillars fed on chokecherry leaves in late summer (found them August 20th) and pupated mid-September. The early instars were green and had a bird (swallow?) like pattern across their backs.

Swallowtail Caterpillar
Swallowtail Caterpillar

As they grew, the bird pattern faded. When they reached about two inches in length they turned brown, stopped eating and became very active. Then they hung themselves horizontally from a piece of silk (appearantly called a girdle) which you can see in the photo. Then they pupated and we have been waiting ever since. We are very excited that spring is approaching here in Big Sky, Montana (although we still have quite a while to wait.) We will send photos of the adults when they emerge. It will be interesting to see which species of swallowtail they are; it is also possible they are Canadian Swallowtails. Also, we wonder if it is possible to determine the gender? Thanks for listening.

Swallowtail Caterpillar
Swallowtail Caterpillar

Dear Bigskybugkids,
This presents an interesting identification challenge. There is an image on BugGuide of a Canadian Swallowtail Caterpillar, Papilio canadensis, that illustrates the “swallow-like” markings, but it also has distinctive horns at the end of the abdominal section. Cherry is listed as a larval food on BugGuide as well. Chokecherry is specifically listed as a larval food of the Two Tailed Swallowtail Caterpillar, Papilio multicaudata, on BugGuide. With regards to the Western Tiger Swallowtail Caterpillar, BugGuide indicates: “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.” Those two characteristics are present in your specimen, but neither cherry nor chokecherry are listed as food plants for the larvae. The images of the Two Tailed Swallowtail Caterpillars on BugGuide show a similar pupil-less eyespot and separated yellow spot, virtually identical to the Western Tiger Swallowtail. Based on the eyespot match and the food plant match, we would suspect the Two Tailed Swallowtail to be the frontrunner. Guess the adult images will have to be the final determination. We suspect DNA may be required to determine the sex of a caterpillar.

Swallowtail Chrysalis
Swallowtail Chrysalis

Awaiting Papilio rutulus or Papilio multicaudata?)
Fri, Jun 12, 2009 at 3:42 PM
After a refreshing 10 month nap…the swallowtails have emerged. It looks like they are Two-Tailed: you were so right. The tell-tale (tail 🙂 ) sign was the _/*thinly*/_ ringed blue/green spot inside the yellow eye spots…the Western looks almost the same but the ring is thicker. Thanks again…and, no, we still can’t tell the boy butterflies from the girls.
(ed. note: We believe this would be from Montana)

Two Tailed Swallowtail
Two Tailed Swallowtail

Dear bigskybugkids,
Thanks so much for sending us the photos of your newly emerged Two Tailed Swallowtails. We will be posting them today as their own posting as well as an update to the caterpillar photos you sent in April.

Two Tailed Swallowtail
Two Tailed Swallowtail

Letter 10 – Swallowtail Caterpillar, but which one???


Catepillar name?
Location: Texas
May 7, 2012 12:15 pm
My class found this at recess today and think it is beautiful. Had a line that went down its spine almost like a heartbeat, or vein. The blue dots changed color from white to blue. Could you help us identify? Found in Helotes, TX (78023); May 7, 2012
Signature: Melissa Spiekerman

Swallowtail Caterpillar

Hi Melissa,
This is one of the Swallowtail Caterpillars in the genus
Papilio, but we don’t feel we are skilled enough to determine the exact species.  Several large black and yellow striped butterflies with tails have similar caterpillars.  BugGuide shows similar looking caterpillars for the Two-Tailed Swallowtail, Papilio multicaudata, the Pale Tiger Swallowtail, Papilio eurymedon, and possibly even the Eastern Tiger Swallowtail, Papilio glaucus.  The orange coloration indicates that this individual is preparing to metamorphose into a chrysalis.

Thank you so much!!!  You just made our class very happy!
Melissa Spiekerman
3rd Grade Teacher
Bob Beard Elementary
TEA Exemplary School

Letter 11 – Swallowtail Caterpillar from Mumbai is Common Mormon


Subject: It’s a caterpillar ,but which species.
Location: India,Maharashtra, Mumbai
November 23, 2015 2:44 am
A couple of weeks ago a beautiful butterfly layed her eggs on my plany of curry leaves.
They where 7-8 but only 1 survived due to weak condition of weather and plant .
But these beautiful caterpillar is of which species and how will it look after becoming a butterfly I want to know.
Signature: Sahil

Swallowtail Caterpillar
Common Mormon Caterpillar

Dear Sahil,
This is the caterpillar of a Swallowtail Butterfly and there are several species that look quite similar, but we are relatively confident that this is a Lime Butterfly Caterpillar, based on this description provided to us by Keith Wolfe in a previous posting on our site:  “I’ve seen hundreds of Lime Butterfly and Common Mormon larvae all across Asia, the two being easily separable by a coffee-colored band between the “eyes” (Lime Butterfly) and prominent blue spots on the head and body (Common Mormon).”  We don’t normally link to Wikipedia, but there is a beautiful set of images documenting the metamorphosis of the Lime Butterfly posted there.  Fluttery has a nice comparison of the similar looking Swallowtail caterpillars.  Just to be certain, we are writing to Keith Wolfe to get verification on our identification.

Correction Courtesy of Keith Wolfe
Hi Sahil and Daniel,
Sorry Bugman, this is in fact a Common Mormon (Papilio polytes, http://www.ifoundbutterflies.org/sp/603/Papilio-polytes/early-stages).  Its caterpillar and those of the Lime Butterfly (P. demoleus, http://www.ifoundbutterflies.org/sp/602/Papilio-demoleus/early-stages) are frequently confused, but a careful check reveals several distinctions.
Best wishes,

Letter 12 – Swallowtail Caterpillar from India


Subject: cateplillar with eyes to scare predators?
Location: gurgaon,india
December 1, 2013 8:41 am
We found this caterpillar in our garden- Gurgaon, India…and it looked beautiful and scary at first sight!!if there is one, does it mean there will be others too in our garden? in fact we saw another green with black strips ( pic-3) caterpillars in our garden!!
Our 8 year old daughter- Arushi- clicked these pictures….and we are very keen to find out more about them( both caterpillars )
Signature: Arushi

Swallowtail Caterpiller
Swallowtail Caterpiller

Hello again Arushi,
Your second caterpillar is a Swallowtail Caterpillar, and in our opinion it is one of the species that feeds on the leaves of citrus trees.  Your photo does not have enough detail for a definite species identification, but we believe this is one of two species.  It is either a Lime Butterfly,
Papilio demoleus malayanus, or a Common Mormon, Papilio polytes.

Letter 13 – Swallowtail Caterpillar nears time for pupation


Subject: Western tiger swallowtail caterpillar?
Location: Santa fe nm
July 5, 2014 9:05 pm
Found this super handsome caterpillar in our yard! He looks pretty close to finding a place for his transition
Signature: Sjhizny

Swallowtail Caterpillar near to pupation
Swallowtail Caterpillar near to pupation

Dear Sjhizny,
There are several butterflies similar looking to the Western Tiger Swallowtail that also have similar looking caterpillars, so your location is helpful in narrowing the possibilities.  According to BugGuide, species other than the Western Tiger Swallowtail,
Papilio rutulus, which range in New Mexico include: the Two Tailed Swallowtail, Papilio multicaudatus, and possibly the Eastern Tiger Swallowtail, Papilio glaucus, which is reported as far west as Texas and Colorado and possibly the Pale Tiger Swallowtail, Papilio eurymedon.  The coloration on this individual indicates it is approaching the time to transform into a chrysalis.  Your image is quite stunning.  

Letter 14 – Swallowtail Caterpillar on Cyprus


Swallow Tail?
Location:  Yenibogazici, Northern Cyprus
October 5, 2010 2:52 am
I can tell from your wonderful site that this is a swallow tail, but which one. It’s pattern doesn’t seem to match with any pics.
Signature:  Senny

Swallowtail Caterpillar: Papilio machaon

Hi Senny,
We just learned on the Butterflies of Cyprus website that
Papilio machaon is the only Swallowtail on Cyprus and that it is “Common throughout most months of the year and widely distributed throughout the island.”  The EuroButterflies website has images of the caterpillar that look exactly like your photo, and they indicate the caterpillars feed on “many species of the Umbelliferae (Carrots) and Rutaceae (Rues).”   You may also read more on the UK Butterflies website.  It is listed on the Butterflies and Moths of North America website where it is called the Old World Swallowtail, but it is unclear if it is considered an introduced species, however this information on the larval foods is interesting:  “Sagebrushes (Artemisia species), including Arctic wormwood and wild tarragon, rarely plants in the parsley family.”  Finally, the Butterflies of Europe website has interesting information, including this:
“Throughout most of it’s range the Swallowtail shows itself to be highly adaptable, utilising a wide variety of habitats including sub-arctic tundra in Canada, prairies, woodlands and arid canyons in the south of the USA; hay meadows, roadside verges, river banks and sub-alpine pastures in Europe; high montane habitats in the Atlas mountains of north Africa, and semi-cultivated habitats in the Mediterranean area.
It’s adaptability extends also to it’s choice of foodplants – in North America the caterpillars usually feed on Compositae ( Artimesia, Petasites ), while in Europe Rutaceae ( Ruta, Haplophyllum ) and Umbelliferae ( Foeniculum, Peucidanum etc  ) are used instead. In Britain however the butterfly is restricted to a single foodplant – milk parsley, and breeds only at a very small number of wet fenland habitats in north-east Norfolk. Individual specimens have been tagged and found to fly over quite a large area, often reaching adjacent fens, but the butterflies do not stray beyond the general area of the broads.
Several centuries ago the species almost certainly occurred as a resident species over a much wider area of southern and eastern England, but later contracted it’s range to the Great Fen – a vast area of wetlands covering Cambridgeshire, Lincolnshire and Norfolk. Following the drainage of this area, and it’s conversion to agriculture, the butterfly was forced to contract it’s range even further – to the Norfolk Broads. In such isolation the genetic diversity would have diminished, causing the so-called “sub-species” machaon brittanicus to become far less adaptable, and to acquire minor differences in appearance from the ancestral stock.

Letter 15 – Swallowtail Caterpillar about to transform


Subject: Caterpillar in the process of becoming a chrysalis?
Location: Southwestern Shaanxi Province, China
September 23, 2013 10:15 pm
Hi Daniel,
Found this on the wall of the bike sheds outside my apartment block and wondered if it was a caterpillar (not sure what species) in the process of starting its pupation? I’d love to know!
Signature: Paul UK

Swallowtail Caterpillar begins pupation
Swallowtail Caterpillar begins pupation

Hi again Paul,
The general shape of your caterpillar, its vertical orientation and the silken girdle holding it upright are all indications this is some species of Swallowtail Caterpillar.

Subject: Chrysalis Update
Location: Southwestern Shaanxi Province, China
September 29, 2013 8:28 pm
Thought you might like an update on the caterpillar which was about to transform. I went to see the progress it was making and it has begun its pupation. It’s weird how different the chrysalis looks from the caterpillar!
Signature: Paul UK

Swallowtail Chrysalis
Swallowtail Chrysalis

Hi Paul,
Thanks for the update on the Swallowtail Caterpillar.  We are very curious about the adult butterfly.  Though this chrysalis shares certain features with our more familiar North American Swallowtail species, including the silken girdle and the upright orientation, that thoracic “thorn” is totally unfamiliar to us.  We hope you send us some images of the adult Swallowtail once it emerges.

October 3, 2013
Hey Daniel,
I have since noticed several more of these pupating swallowtails around our garden. Most of them are upright although 1 or 2 have been horizontal on the ceiling of the bike sheds. They all have the silk girdle holding them in place and the thoracic thorn, although some thorns point towards the head and some to the abdomen.

Thanks for the update Paul.

Letter 16 – Swallowtail Caterpillar with Osmeterium


Black Swallowtail Caterpillar Not Happy!
Thanks to your site I was not alarmed when I disturbed this caterpillar. I had already identified him & thought you’d like to see him in action. Warm regards,
PS He put out quite a stink as well!

Hi Donna,
In the event some of our readers don’t know what you are talking about, we should inform them that Swallowtail Caterpillars have a fleshy organ that resembles horns that is normally retracted, but can be everted when the caterpillar is disturbed. The organ emits an odor that some predators, and you as well, find offensive.

Letter 17 – Swallowtail Caterpillars from Mexico continued


Location: Northeast Mexico
May 16, 2014
Yes, I guess it wasn’t that caterpillar. A bird must have taken it or something. It kept coming back for that day, especially on the parsley. The first pictures is among the best I could get. It was the black swallowtail from here http://www.iwallpapersfive.com/eastern-black-swallowtail-butterfly-with-a-grateful-prayer-and-a-thankful-heart-eastern-black.html/eastern-black-swallowtail-butterfly-with-a-grateful-prayer-and-a-thankful-heart-eastern-black-2
Anyway, I later found a quite a few caterpillars on the parsley that look exactly like those of the eastern black swallowtail blog post, so maybe those will become that black and blue butterfly.
A couple of the caterpillars were good sized, some were very small, but they have all kept growing. Right now you can see many at different stages, here I send some pictures.
I found a chrysalis on a crate right by where I had found the first bigger caterpillar, the one that was possibly a tiger swallowtail, maybe that one will come out.
Signature: Alex

Female Black Swallowtail Ovipositing
Female Black Swallowtail Ovipositing

Hi Alex,
This definitely represents a different Swallowtail species than your previously submitted image.  This does appear to be a female Black Swallowtail (females have blue markings on wings) and she appears to be laying eggs.  The caterpillar does appear to be that of a Black Swallowtail feeding on parsley.  Since you are in Northeastern Mexico, it is entirely possible that you live within the range of the Black Swallowtail.
  Black Swallowtail Caterpillars are known as Parsley Worms.

Parsley Worm
Parsley Worm

Thank you Daniel! It’s been fun trying to keep up with all these bugs..

Letter 18 – Swallowtail Chrysalis


What Is It?
Location: Albuquerque, NM
February 29, 2012 3:28 pm
found on back of rock in Albuquerque, NM yard couple of months ago
Signature: Pat

Swallowtail Chrysalis

Hi Pat,
This is the Chrysalis of a Swallowtail Butterfly.  Just prior to pupation, the Swallowtail caterpillar spins a silken strand that girdles its body, keeping the chrysalis upright.  This is a distinctive identification for most Swallowtails.

Letter 19 – Swallowtail Chrysalis


Subject: Stalker Bird!!!
Location: Negeri Sembilan, MALAYSIA
September 6, 2014 11:41 pm
7 September 2014 2:00 p.m.
Hi again. I will have two id requests today, if you don’t mind. This is my first;
I was out in the garden photographing bugs (I have recently discovered the world of macro photography). Around the porch area, I found a bird thingy. It scared the living daylights out of me. Upon closer looking and some poking via a stick, I figured it was a moth pupa, but I don’t know which moth caterpillar make it. Above it, there is a single strand of silk. It is about 7 cm (3.8 inches) long. Is it a bird decapitated by a spider or a pupa. If it’s a pupa, what pupa is it?
Signature: TFO (Totally Freaked Out)

Swallowtail Chrysalis
Swallowtail Chrysalis

Dear TFO,
The quality of your images is quite poor, however we are able to distinguish the outline of the Chrysalis of a Swallowtail Butterfly in the genus
Papilio that was intact prior to your poking it with a stick.

Swallowtail Chrysalis
Swallowtail Chrysalis

Letter 20 – Swallowtail Chrysalis


Subject: Moth Chrysalis
Location: Boulder, CO
March 20, 2016 3:03 pm
We found a chrysalis tucked away in a lonely shoe about 3-4 months ago (Sept or Oct). A friend had left her leather dancing shoe under our couch, and when I picked it up, out fell this little guy. It was attached up near the toe by two silk anchors.
Sadly he fell quite a ways, I’m rather tall so he got the brunt of a 3 foot drop to our hardwood. The Chrysalis is currently hanging in a mason jar with ventilation, but I’m rather curious for more information about it. Thank you for your time!
Signature: -FC

Swallowtail Chrysalis
Swallowtail Chrysalis

Dear FC,
This chrysalis belongs to a butterfly, not a moth.  We believe it is a Swallowtail Chrysalis.  Most Swallowtails produce upright chrysalides, that are held in that position by a silken girdle.  This Tiger Swallowtail Chrysalis from BugGuide looks similar.

Swallowtail Chrysalis
Swallowtail Chrysalis
Swallowtail Chrysalis
Swallowtail Chrysalis

Letter 21 – Swallowtail Chrysalis


Subject: What is it?
Location: Monrovia, CA
September 19, 2016 3:00 pm
Hello Daniel,
This is Amy from Amy Oliver’s class. Can you identify this bug?
Signature: Thank you!

Swallowtail Chrysalis
Swallowtail Chrysalis

Hi Amy,
It was nice meeting you in the photography class at Glendale Community College.  This is the Chrysalis of a Swallowtail Butterfly in the genus
Papilio.  The Swallowtails produce a chrysalis that is held upright with a silken girdle.  We believe the most likely candidates are Giant Swallowtail, Anise Swallowtail and Western Tiger Swallowtail.  If you could give us some idea of what plants were growing near the sighting, we might be able to narrow down the species.

Letter 22 – Swallowtail Chrysalis


Subject:  Unknown chrysalis
Geographic location of the bug:  Columbus, Ohio
Date: 11/02/2018
Time: 04:54 PM EDT
Your letter to the bugman:  So, saw this chrysalis on the outside of a building.  No clue who made it.
How you want your letter signed:  Amber

Swallowtail Chrysalis

Dear Amber,
Most butterflies have a chrysalis that hangs downward from the tip of the abdomen from a silken button spun by the caterpillar, but most Swallowtail caterpillars have an upright chrysalis that is also supported by a silken girdle.  Your chrysalis looks like a Swallowtail Butterfly chrysalis, but we are not certain of the species.

Letter 23 – Swallowtail Chrysalis from China


Subject: Chrysalis Update
Location: Southwestern Shaanxi Province, China
September 29, 2013 8:28 pm
Thought you might like an update on the caterpillar which was about to transform. I went to see the progress it was making and it has begun its pupation. It’s weird how different the chrysalis looks from the caterpillar!
Signature: Paul UK

Swallowtail Chrysalis
Swallowtail Chrysalis

Hi Paul,
Thanks for the update on the Swallowtail Caterpillar.  We are very curious about the adult butterfly.  Though this chrysalis shares certain features with our more familiar North American Swallowtail species, including the silken girdle and the upright orientation, that thoracic “thorn” is totally unfamiliar to us.  We hope you send us some images of the adult Swallowtail once it emerges.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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20 thoughts on “What Do Swallowtail Caterpillars Eat? A Friendly Guide to Their Diet”

  1. I concur, it will most likely emerge early morning and begin to dry it’s wings which takes ~30 mins or so. Once the wings are dry the butterfly will be off. You may are may not see it flying around, but chances are there are others in the area, so keep an eye out and you will probably spot one this summer, especially within the time period that this one emerges.

  2. I should also say, if you really want to know when it will emerge, you can look at what I believe you are calling the face (part on top with “horns” facing the fence) and you will see it begin to become translucent and probably appear somewhat of an orange color. Once it begins to change color in the “face” region it will emerge in less than 48 hours (if it is really translucent and orange in color it will probably emerge in less than 24 hrs) .

  3. Hey Daniel,

    I have since noticed several more of these pupating swallowtails around our garden. Most of them are upright although 1 or 2 have been horizontal on the ceiling of the bike sheds. They all have the silk girdle holding them in place and the thoracic thorn, although some thorns point towards the head and some to the abdomen.

  4. Hey Daniel,

    I have since noticed several more of these pupating swallowtails around our garden. Most of them are upright although 1 or 2 have been horizontal on the ceiling of the bike sheds. They all have the silk girdle holding them in place and the thoracic thorn, although some thorns point towards the head and some to the abdomen.

  5. Oh. Now it makes sense. I have seen another guy with that butterfly on this website. It’s probably a Tropical Swallowtail Butterfly. The nation along with Singapore has been experiencing an invasion of them. Thank for the info.

  6. Found them on my fennel this morning,chicken won,t eat them, thought they might be poisnous. Mighty pretty buterflies and won,t be feeding them to the chickens any more.

    • You are wecome Sahil. Also, Keith Wolfe corrected the identification. This is not the Caterpillar of a Common Lime Butterfly. We misidentified the larva of the Common Mormon.

  7. Thanks so much for the help identifying this guy. He hatched today and flew off, probably to get eaten fairly quickly (it would have been perfect timing 2 days ago, but now there is snow on everything and this swallowtail is bright yellow). Thank you again for the help!

  8. Hi,

    I have a grapefruit tree and I am having these caterpillars attack the young plant relentlessly. Now, i dont mind them eating a few leaves and making the garden colourful with butterflies but the young plant is dying because of these caterpillars. Kindly do tell me how to avoid them (for the time being, so that the tree can grow.) currently I am going organic and spraying neem oil on the plant to dissuade any caterpillars. would love to know if any specific action can be taken to save the tree.

    P.S: I have a couple of picture of this that are of good quality so if anyone is looking for any collection. Do mail me. would be glad to give it away.


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