Eastern Tiger Swallowtail Butterflies: Their Caterpillars Are Unbelievable

The Eastern tiger swallowtail is one of the most recognizable butterflies in the United States, thanks to its striking black and yellow wings. Not only is it beautiful to look at, but it also plays an important role in the ecosystems of the eastern United States. Here are 7 fascinating facts about Eastern tiger swallowtails and their important roles.

Eastern Tiger Swallowtail
Scientific name: Papilio glaucus
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Genus: Papilio

1. They are beautiful butterflies

The Eastern tiger swallowtail is a striking big butterfly with a size ranging from 3.5 to 5.5 inches (9 – 14 cm). It is significantly larger than the Monarch butterfly. The wingspan of this species is approximately 2.5-4.5 inches (6.2-11.4 cm), with females being a little bigger than males.

You can easily recognize these butterflies by their bright yellow and black striped wings, resembling a tiger’s pattern. Male tiger swallowtails have beautiful yellow wings surrounded by a black border with yellow spots. There are also black stripes going across the tops of their wings.

Eastern tiger swallowtail male vs female

The main difference between males and females is their hind wings. On the females’ hind wings, there are rows of noticeable blue stripes and a shimmering blue wash, along with an orange minor spot on the upper side hind wing. Males, on the other hand, do not have this feature.

Besides the yellow color like the males, the females also have a black version. With the black color, you can hardly see the black tiger stripes on their wings. The dark form which is known as dimorphic coloration is more prevalent in the south, while the traditional yellow color is more popular in the north.

The black eastern swallowtail

It is believed that this dark morph is a color mimic of the pipevine swallowtail. This species live in the same areas of the Eastern and have an unpleasant taste to deter predators.

The yellow females are more attractive to the males, while the black females are less noticeable to predators.

Both genders have a lengthy tail-like extension at the bottom of each hindwing. Papilio means butterfly and Glaucus is gray in Latin.

Papilio glaucus is the scientific name of the Eastern tiger swallowtail. the Latin word for. in Latin. Hence, their name means gray butterfly.

2. Range and Habitat

The Eastern tiger swallowtail comes from North America east of the Rocky Mountains, from Ontario to the Gulf coast and northern Mexico. They are also found in New Hampshire.

These beautiful butterflies can be spotted soaring high above deciduous woods near streams, rivers, marshes, forest borders, and river valleys. They can also be found in private gardens or parks.

The Eastern tiger swallowtail is designated as the official butterfly in 5 states: George, Alabama, South and North Carolina, and Delaware. Meanwhile, Virginia has selected it as their official state insect.

3. They like to be alone

Eastern tiger swallowtails, like most butterflies, are generally solitary creatures. However, a group of swallowtail males “puddling” can occasionally be seen. This occurs when the males congregate in great numbers in mud puddles or other damp areas to suck salts, minerals, and other substances from the ground. This behavior is most commonly observed in male butterflies rather than females. They do this to restore salts lost during mating.

These butterflies, both males and females, are exceptional flyers. In Maryland, it is not uncommon to see a group of 50 butterflies soaring 50 meters above the tops of tulip trees.

A group of males are puddling

Like other bird species, Eastern tiger butterflies are diurnal. They are primarily active during daylight hours, and when they take a break, they often rest with their wings spread open. These species are easily attracted by gardens that are filled with a plethora of flowers.

The Eastern Tiger Swallowtail species make 3 flights: one from February to November in the deep South and two cycles from May to September in the North.

Fact: Spiritual meaning
Swallowtail butterflies are frequently depicted in culture to symbolize grace and the free nature of the human soul. They are also linked to ideas of hope, perseverance, transformation, and life.

4. Diet

The caterpillars of Eastern tiger swallowtails are herbivores. They feast on the leaves of various woody plants such as birch, willow, cherry, ash, cottonwood, and tulip. These voracious larvae are capable of devouring entire leaves from their host plants.

While these larvae may eat a large number of leaves, they are not known to cause significant harm to their hosts. In great numbers, though, they can defoliate a tiny tree or shrub.

Host plants for tiger swallowtail
The species are feeding on nectar

The main food of both male and female adults is nectar from a diverse range of plants. Those can include Japanese honeysuckle, thistles, milkweed, azaleas, lilac, butterfly bush, wild cherry, ironweed, phlox, and other urban flowers. This butterfly species has a particular fondness for aromatic lilies.

To drink nectar, these adult Eastern tiger swallowtails use a long and flexible tube-like nose. When not in use, the proboscis curls up into a curve, but when it is time to feed, it unravels to allow for sipping.

1,034,201 plays

5. Life cycle

Eastern tiger swallowtail butterflies mature in spring and their main purpose is to mate and generate the next generations. The butterflies from the north will generally have two broods, while those from the south will brood three times. Their breeding range extends throughout most of the United States and Canada.

Males with scents like pheromones fly from place to place (especially places with lots of nectar), actively looking for a mate. This is known as “patrolling.” If the females agree, they will flutter about each other before landing and mating. If they feel threatened when mating, the female will carry the male to a safer location.

After mating, female tiger swallowtails lay about 250 green eggs on the leaves of the common host plants such as sweet bay Magnolia, tulip tree, and wild black cherry.

These insects undergo a full metamorphosis. This means they will go through four different life stages. The egg takes about a month to mature into an adult.

Caterpillar stage

Depending on the temperature and host plant, the eggs hatch within 5 to 10 days. The newly hatched caterpillar will have a brown and white appearance, resembling bird excrement. For the first few molts, it will maintain this appearance.

A young larvae

As the caterpillar molts for the third time, it transforms into a green color. It has a big and rounded head with 2 big eye spots. Compared to other species, its head is larger than the typical caterpillar’s head, almost resembling a helmet. Near the head, there is a yellow band on its body.

A mature larvae is green with yellow band

The Papilio glaucus caterpillar begins consuming the leaves of the host plant and can develop to be 2 inches long.

Pupa stage 

After three to four weeks of feeding on leaves and molting for the fifth time (the fifth instar), the species makes a chrysalis among dead leaves on the ground. This chrysalis is greenish-brown in color and slightly over an inch long.

The pupa stage lasts for 10-20 days in the spring and early summer. However, if the pupa phase is in late summer and early autumn, it will enter diapause.

The pupae will remain in a dormant state throughout the winter. To keep themselves from freezing, they create glycerol and trehalose, which function as antifreeze. When the temperature is warmer, they emerge and become the first Eastern swallowtail butterfly in spring.

Adult stage: A lovely butterfly will emerge from the cocoon one month after the egg was deposited. It will no longer grow after emerging. Its lifespan only lasts for one to two weeks, maybe a month.

6. Their caterpillars are amazing

The young larvae of Eastern tiger swallowtail species look like bird droppings. This is their survival adaptation in the world full of predators like this. Snakes, lizards, and birds are not fascinated by devouring bird dung.

These caterpillars are not poisonous to touch.

When getting older and greener, these species have another way to protect themselves. They have black, yellow, and white eyespots on their huge head. However, these are not their real eyes. The huge circular eye spots make appear larger and less appealing to predators. The Eastern tiger swallowtail caterpillars are the Caterpie character in Pokemon.

The Caterpie in Pokemon

Besides their appearance, these caterpillars have a special defense mechanism. When they feel danger, they will drop off the leaves and hang on silk threads, making them difficult to spot by predators.

If perturbed, the Eastern swallowtail butterfly caterpillar can extend their orange osmeterium, a hidden organ within their body. These hidden organs resemble horns or a snake’s tongue and can emit a foul odor that deters potential predators.

7. Eastern tiger swallowtail vs Canadian tiger swallowtail

The Canadian tiger swallowtail is a species of tiger swallowtail butterfly and a member of the family Papilionidae. Therefore, they have many in common with the Eastern butterflies. However, you can still differentiate between them. You can read more about the differences between the Eastern and Canadian tiger swallowtail here.

8. Threat and predators

The Eastern tiger swallowtail butterfly is preyed upon by various creatures, including birds such as the white-breasted nuthatch, red-winged blackbird, sharp-shinned hawk, downy woodpecker, great-crested flycatcher, and common crows.

Insects like the green darner and bald-faced hornet eat the butterfly. Some mammals, like the Virginia opossum, raccoon, and, eastern gray squirrel, are also known to hunt this butterfly as well.

The Eastern tiger swallowtail caterpillars can be eaten by numerous predators, including wasps (Ichneumon wasps and braconid wasps), birds (yellow warblers, Eastern phoebes, and Baltimore orioles), small mammals (shrews and chipmunks), and spiders (yellow garden spiders or wolf spiders).


  • https://nhpbs.org/natureworks/easterntiger.htm. “Eastern Tiger Swallowtail”.
  • Clarke, Cyril and Clarke, F.M.M. Systematic Entomology. “Abnormalities of wing pattern in the Eastern Tiger Swallowtail butterfly, Papilio glaucus”. Vol. 8, 1983.

I'm so fascinated about animals and want to share with you these amazing, interesting, amusing and beautiful creatures. Hope you enjoy it!

2 thoughts on “Eastern Tiger Swallowtail Butterflies: Their Caterpillars Are Unbelievable”

  1. You know you’ve made it in the butterfly world when you’re an Eastern Tiger Swallowtail. They’re like the supermodels of the butterfly kingdom, with those stunning black stripes and yellow wings.

  2. The larvae of these butterflies are amazing. The way they defense themselves is more than spectacular. Now I know why it’s brought to the POkemon series


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