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U.S. Forest Service

Tigers on the Wind: The Eastern Tiger Swallowtail

By Stephen Buchmann, Pollinator Partnership

Who among us isn’t mesmerized by vibrant colorful butterflies flying over a meadow or garden? Since ancient times butterflies, along with dragonflies and bees have been perhaps, the most universally cherished insects by human cultures around the world. The ancient Greek term for butterfly, psyche (Ψυχη), is also rooted in Greek mythology. Psyche was the embodiment and deification of the human soul.

Like many boys, caterpillars fascinated me. I brought eggs and caterpillars of western swallowtails home, raising them until they pupated and adults emerged as one of North America’s showiest butterflies. Metamorphosis, the transformation of an insect through its life stages; egg, larva (caterpillar), pupa or chrysalis into winged adult is nothing short of miraculous. Entomologists still do not understand all of the details of the process especially in the pupa when the larval cells are reshuffled into adult organs.

Humble “worms” changing into winged creatures before their eyes similarly awed the ancients. The Greek word ‘psyche’ is interwoven with the concept of spirit or breath, an animating life force in humans, and other animals. From Greek mythology, Psyche was the embodiment and deification of the human soul. She is often depicted in ancient statues and tile mosaics as a beautiful young woman with butterfly wings.

Eastern tiger swallowtail female. Eastern tiger swallowtail female (upperside). Photo by Penny Stritch.

The Eastern Tiger Swallowtail butterfly (Papilio glaucus) is one of the most common and beautiful eastern butterflies. Individuals can be found anywhere east of the Mississippi river and a bit farther west into the Great Plains states. There are also populations in several Mexican states.

Swallowtails are very large insects. When basking in the sun, their outspread wings can be 8 to 14 cm (3 to 5.5 inches) from tip to tip. Their colors are vibrant. Broad yellow wings are edged by black and with four stripes, like tapering chevrons from the forewing margins downward into the yellow wings. The bottom edges of the hind wings are especially colorful with bluish scales and one or more red spots. Male Tiger Swallowtails generally have darker blacks and none of the bluish and red scales on their hind wings. Interestingly, there is a black morph, where black replaces the broad yellow expanses. The black morphs also have the bluish and red wing scales on their hind wings.

Although they are solitary creatures, often flying high in the treetops, you can sometimes spot a special sight when a group of swallowtail males is “puddling.” Male butterflies come together at damp places in the soil and drink water. The water contains sodium ions and various amino acids, which appear to allow them to live longer. Adults of both sexes take nectar from a wide variety of native and exotic garden plants.

Females lay their large green eggs singly on plants in the Magnolia and rose families. Common host plants include tulip tree (Liriodendron tulipifera) and wild black cherry (Prunus serotina) and sweet bay Magnolia (Magnolia virginiana). The nearly identical looking western swallowtail (Papilio rutulus) feeds on cottonwoods, aspens and others.

Eastern Tiger Swallowtail caterpillars are amazing animals. Young caterpillars are brown and white and resemble bird droppings. Can you guess why? Later, as they mature, the caterpillars turn bright green and have two amazing black, yellow, and blue false eyespots on the thorax above and behind their true eyes. The true head of the caterpillar is small, inconspicuous, and tucked under the body. If disturbed, the caterpillar is a quick-change artist. Now, instead of a harmless caterpillar, we or a bird or small mammal, are confronted with something very different: a snake’s head with glaring eyes a nose and mouth! Presumably, birds and other potential predators are put off by this impressive “snake in caterpillar’s clothing” mimetic display and the swallowtail is spared. If touched or pecked by a lizard, bird, or inquisitive human, the larvae evert a set of bright orange glands (the osmeteria) from the neck region. These produce a foul-smelling blend of defensive acid secretions that are wiped onto the attacking animal. This level is mimicry is astonishing and has been commented upon by many surprised naturalists. Each time I find a giant swallowtail (Papilio cresphontes) on a citrus branch in my yard, I am amazed at the early and late mimicry (first a bird dropping, then a snake head) and how natural selection has evolved the intricate warning displays, a visual shout of “Back Off!”

The Eastern Tiger Swallowtail butterfly is the state butterfly of Alabama, Delaware, Georgia, and South Carolina. This species is commonly seen from spring to fall and produces two broods in the north, and three life cycles in the southeastern states.

For Additional Information

For More Information about swallowtails and other butterflies, try these online Resources.