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Tennessee State Butterfly Lesson: The Zebra Swallowtail

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Tennessee's state butterfly is the gorgeous zebra swallowtail. It was designated in 1995 and is one of many swallowtail species that are distributed across the United States, and around the world. This article tells you what you need to know about this wonderful butterfly.

The Basics:

  • What is the scientific name? Protographium marcellus
  • What does it eat? The larvae eat the leaves of pawpaw trees
  • Will it seriously damage plants or trees? No
  • Is it rare? No, this species is generally common throughout its range.
  • Where does it occur? This species is most common in the southeastern US.
  • Can you raise it from caterpillar to adult? Yes, if you give it plenty of the food plant you found it on.

The Zebra Swallowtail Butterfly's Scientific Name

Tennessee's state insect belongs to a group of butterflies that are distributed around the world, from chilly northern regions to steamy tropical zones. Northern species are some of the most familiar butterflies you will see. They are big, beautiful, and often take nectar at flowers in the bright summer sun. Tropical swallowtail species are among the world's most breathtakingly beautiful insects, with some showing bright shimmering colors and iridescence. This group is known by scientists as the family Papilionidae. There are many kinds of butterflies in the group, and they all share some special characteristics.

The scientific name of the zebra swallowtail butterfly is Protographium marcellus. That means the genus name is Protographium and the species name is marcellus. Scientific names are always in italics.

As a middle school teacher myself, I wrote this guide to be useful for both students and teachers. It's a great place to start for research ideas and science fair projects!

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The Zebra Swallowtail

This beautiful insect is aptly named, with black stripes on a clear white background. Like the giant swallowtail (above), it is a northern representative of a group of butterflies that have many varieties throughout the Neotropics. You will seldom find this species outside of the southern states, but it will sometimes wander north, for example along the Mississippi River Valley.

Like all other swallowtails, the flight is strong and gliding, but they will often stop to nectar. At these times you may see several visiting the same nectar source. Males also participate in a behavior known as "puddling," which is when a group of butterflies congregates at wet sand or mud to draw nutrients.

Swallowtail Butterfly "Tails"

Swallowtail butterflies likely get their common name from the tails that grace their hindwings, which in some ways recall the forked tails of birds called swallows. Researchers who study insects ("entomologists") believe that these tails may attract the attention of predators, who are more likely to attack this part of the butterfly rather than the vital body or head. So if a hungry bird or lizard snaps at the tails, the butterfly will only lose a bit of wing and can live to fly, mate, and reproduce.

In many species the tails have a central spot, reminiscent of an eye. This may further the illusion that the expendable tails on the swallowtail's wings are where the action is for a predator to strike.

Often you will see swallowtail butterflies with the tails missing; in some individuals, the missing part of the wing is in the shape of a bird's beak!

Zebras, looking like butterflies.

Zebras, looking like butterflies.

Bright Stripes – How the Zebra Swallowtail Got Its Name

There are very few butterflies in North America that you can confuse with the zebra swallowtail. The bright white and black zebra stripes are visible from far away, especially in full sunshine. The underside is very similar. The butterfly has a strong, gliding flight, and enthusiastically feeds on nectar in full sunshine.

I have seen flowering bushes with ten or more zebra swallowtails all flying and feeding at the same time, and it is a beautiful sight.

Two Color Forms of the Zebra Swallowtail Caterpillar

Zebra swallowtail caterpillar, light form

Zebra swallowtail caterpillar, light form

Zebra swallowtail caterpillar, dark form

Zebra swallowtail caterpillar, dark form

Features of Swallowtail Caterpillars

The caterpillars of the zebra swallowtail, and all swallowtails, have some fascinating habits and features. The most distinctive of these is the presence of an organ called an "osmeterium." This is a orange-red, forked gland that the caterpillar can pop out from behind its head when it's disturbed or threatened. The gland looks a lot like a small snake's tongue, and it also smells bad. This remarkable evolutionary feature of swallowtail caterpillars is a reliable way to know if the caterpillar you have found is in fact a member of the family Papilionidae.

Zebra swallowtail caterpillars come in two different color forms, light and dark; both forms are smooth, with thin cross-wise stripes.

Another unusual feature of these caterpillars: they can be cannibalistic.

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Complete Metamorphosis

"Complete metamorphosis" is the term used to describe the life cycle of insects that go through a four-stage sequence of forms. For butterflies, this means egg-larva-cocoon/chrysalis-adult. It helps to take the butterfly as the example, although dragonflies, bees, wasps, flies, beetles, and many other insects also go through complete metamorphosis. Like butterflies, they all have larvae and all of the other developmental stages.

The zebra swallowtail butterfly is typical of the insects that undergo complete metamorphosis. The egg is laid on a variety if leaves, and the caterpillar that hatches out eats the leaves of the plant. As it grows, it sheds its skin, also known as molting. The stages between molts are called instars, and after the last instar, the caterpillar sheds its skin one more time.

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The last time the caterpillar sheds its skin, it enters the cocoon/chrysalis phase, known by scientists as "diapause." It's also called a "pupa." Inside the pupa, the insect's cells are rearranging. They actually break down into a kind of goop, and then reassemble to form the body and wings of the adult butterfly or moth.

The final "instar" occurs when the insect hatches out of the pupal skin. It is now ready to mate and continue the cycle. The adult feeds just enough to promote the goal of mating and laying eggs; other than that, it has no purpose on this planet.

The zebra swallowtail occurs throughout the eastern United States, although it's much less common in the northern part of its range.

The zebra swallowtail occurs throughout the eastern United States, although it's much less common in the northern part of its range.

The Zebra Swallowtail's Range

The zebra swallowtail butterfly occurs throughout the eastern United States, including, of course, Tennessee. It is very common throughout the southern states, but becomes increasingly rare farther north. I once found an individual nectaring on milkweed in southern Wisconsin; at the time, this was a new record for the county, and was considered quite a rarity that far north.

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Resources

The following sources were used for this guide:

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

Comments

Miebakagh Fiberesima from Port Harcourt, Rivers State, NIGERIA. on January 22, 2021:

Hello Bughouse, these butterflies were becoming very rare in my part of the country Nigeria. I live on a delta coastline on the Atlantic. I believe it is due to destruction of vegetation. Thanks for sharing.

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