In 2012, the State Legislature designated the Eastern Tiger Swallowtail (Pterourus glaucus) as the official butterfly of North Carolina.
It is believed that artist and mapmaker John White, governor of Roanoke Island (the “Lost Colony”), was the first to draw the eastern tiger swallowtail. This painting was made sometime around 1587!
Tiger swallowtails are large, active butterflies, and are common across their range (eastern North America) in habitats as diverse as woods and fields to roadsides and backyards. They are very strong fliers, and visit a wide variety of flowers, and will readily visit flowers planted in your yard and garden. Swallowtails also use a wide variety of plants and trees on which they lay their eggs. Hornbeams, cherries, maples, elms, willows, and sassafras are just some of the plants the caterpillars will eat.
Speaking of tiger swallowtail caterpillars, they’re pretty amazing too. When they first hatch, they actually look like bird droppings! Since not a lot of animals will eat bird excrement, this serves as a pretty good camouflage.
Another defense mechanism tiger swallowtail caterpillars use is the osmeterium, which is the antler-like structure seen in the above photo. This structure contains chemicals that can be both physically irritating, as well as poisonous, to potential predators.
A third defense mechanism is found in larger tiger swallowtail caterpillars, and that is the large eyespots found on the “shoulders” of the caterpillar. One hypothesis suggests these eyespots and the caterpillar’s green color, as well as the forked appearance of the osmeterium, resemble the face and head of a green snake.
Adult tiger swallowtails come in the bright yellow and black color pattern, and female tiger swallowtails also have a darker morph. Female tiger swallowtails also tend to have a lot more blue on their hind wings than the males.
The dark morph of the tiger swallowtail is a mimic of the poisonous pipevine swallowtail, whose caterpillars feed on the toxic leaves of the pipevine. By mimicking a poisonous relative, female tiger swallowtails can avoid being eaten by predators. This kind of mimicry is called Batesian mimicry.
These active, colorful butterflies have always been one of my favorites. They aren’t as common in Florida, where I grew up, so seeing one was always a treat. Now that I live in the Triangle area, eastern tiger swallowtails are a summer mainstay. I can always count on seeing one flitting through my backyard on its way to visit my coneflowers, or cruising along a river or a trail in the woods when I’m out and about.
Does your state have an Official Butterfly? How about an Official Insect (North Carolina’s is the honey bee)? Let me know in the comments!
If you have any suggestions for future topics you’d like to see in this blog, please leave them in the comments!
*All photos by the author, unless otherwise noted*
Postscript: I made a little video a few years ago of some of the butterflies in the butterfly house at the Durham Museum of Life and Science. While none of these are tiger swallowtails, they showcase some of the amazing diversity in Lepidoptera as a whole. I hope you enjoy the video (and maybe subscribe for more videos like it!)