Eastern Tiger Swallowtail

Papilio glaucus

Cool fact: Swallowtails in the egg stage resemble bird droppings, a means to keep predators away.

The first known drawing of a North American butterfly was of an eastern tiger swallowtail, sketched in 1587 by John White, who was traveling with Sir Walter Raleigh during his third exploration of Virginia. White named his drawing Mamankanois, which is believed to be an Algonquian word for “butterfly.”

One of the most common butterflies in the eastern US, the eastern tiger swallowtail can be found anywhere east of the Mississippi River, ranging from southern Vermont to Florida (interestingly, not in the Florida Keys) and a bit farther west into the Great Plains states. In the south, adults are seen from February to November, during which they produce three broods; in the North, they are seen from May to September and produce only two broods.

Common habitats include woodlands, fields, rivers, streams, gardens, and even roadsides. Because it has adapted to so many different habitats and host plants, it has likely developed genetic traits that allow it to tolerate a wide variety of foods (polyphagous)— probably the most of all 560+ species of swallowtail butterflies in the world!

Swallowtails have a wingspan of 3 – 5 ½”; females are larger than males and southern individuals are larger than their northern counterparts. Males are yellow with four black “tiger stripes” on each fore-wing; the outer edge is black with a row of yellow spots and the veins are marked with black. The lower middle area of the hindwing is black with yellow spots along the margin. The inner margin of the hindwing has small red and blue spots; the forewing margin has a yellow bar broken into spots.

Females may be either yellow or black, or dimorphic, which means having two distinctly different appearances within the same species. The yellow morph has similar coloring to the male, but with a band of blue spots along the hindwing; the dark morph is almost completely black.

Eastern swallowtails are easily confused with Canadian swallowtails. The easiest way to distinguish them is by the length of one of the four black stripes on the wing—the second-to-lowest is longer on the Canadian swallowtails. Also, the black stripe along the abdomen is slightly thicker in Canadian swallowtails.

Metamorphosis is the transformation of an insect through its life stages: egg, larva (caterpillar), pupa or chrysalis, into winged adult. Scientists still don’t understand the details of this process, especially when larval cells in the pupa restructure into adult organs. Another of nature’s mysteries!

Females lay single eggs on host plant leaves, preferably near nectar sources. The eggs are large for a butterfly, round and green, turning yellowish green with reddish dots. After 4 – 10 days, the hatched caterpillar feeds on the leaves of the host plant, e.g., magnolias, roses, wild black cherry, ash, cotton-wood, lilac, tulip poplar, and willow. It’s supported on the plant with the leaf edges folded over itself and held together with silk.

Young caterpillars are brown and white, turn bright green as they mature, and develop two black, yellow, and blue false eyespots on the thorax, resembling a snake’s head. Birds and other predators are often put off by this display, but if not, the caterpillar emits a foul-smelling acid defensive secretion to further discourage the attacking animal. When the caterpillar reaches a length of two or more inches, it develops a cocoon, or chrysalis. The chrysalis is about 1.3” in length and hangs from a surface by a silk “girdle” around the thorax, with a silk pad at the base. It varies in color, from off-white to dark brown, often spotted with green and dark brown, and is found on tree trunks, fence posts, and in ground litter. This stage lasts nine to eleven days, or over winter hibernation in locations with cold months.

Maine has more than 120 butterfly species, all of which play important ecological roles as pollinators and are part of the food chain for larger insects, birds, amphibians, reptiles, and small mammals.  About 20% of Maine’s butterflies are considered Extinct, Endangered, or of Special Concern, so in 2007, the Dept. of Inland Fisheries & Wildlife developed a multi-year Maine Butterfly Survey in an effort to learn about their distribution, habitat, flight behavior, etc. This work is supported by volunteer contributions, The Nature Conservancy, the State Wildlife Grants program (USFWS), and state revenues from the Loon License Plate, Chickadee Check-off, and Maine Outdoor Heritage Fund.

“Cool Facts”

• The ancient Greek term for butterfly – psyche – was a mythological concept of spirit or life force in humans and other animals, often depicted in statues and mosaics as a beautiful young woman with butterfly wings.
• Swallowtails in the egg stage resemble bird droppings, a means to keep predators away.
• Usually solitary, male butterflies congregate on mud, damp gravel ,or puddles where they drink water that contains sodium ions and amino acids, which aid reproduction and appear to allow them to live longer. This behavior is called, not surprisingly, puddling.
• The eastern tiger swallowtail is the state butterfly of Alabama, Delaware, Georgia, North and South Carolina, and the state insect of Virginia.

—by Jayne Winters 

Resources:

• https://en.wikipedia.org/wiki/Papilio_glaucus
• https://www.fs.usda.gov/wildflowers/pollinators/pollinator-of-the-month/TigerSwallowtail.shtml
• https://www.maine.gov/ifw/fish-wildlife/wildlife/species-information/invertebrates/butterfly-survey.html
• https://www.animalwelfareissues.com/six-fun-fascinating-facts-of-the-eastern-tiger-swallowtail-you-didnt-know/

 

If you love learning about Maine’s wildlife, we recommend our monthly blog, Birding with Jeff and Allison.