Year of the Pollinator Series – June: Eastern Tiger Swallowtail

Presenting: Awbury’s 2018 series on pollinators– from wasps to wind! 

Monthly articles will correspond with our programming and our “Pollinators FOUND at Awbury Arboretum” art show and scavenger hunt.

Articles written by La Salle student and Awbury intern Dan Sardaro.

June 2018 – EASTERN TIGER SWALLOWTAIL

Eastern Tiger Swallowtail

Eastern Tiger Swallowtail

Now that the warm months are upon us, you’ve probably seen the abundance of plant, animal, and insect life that has repopulated your local neighborhood. One quintessential signal of life that the summer months bring us is the butterfly, an insect that is both beautiful and graceful as it is necessary to sustaining several key plant species. As the month of June progresses, one butterfly that you’ll see move back into your garden or local park is the eastern tiger swallowtail, a magnificent creature that is quite the tactical pollinator. Our tile this month shows Karen Singer’s recreation of a brightly colored swallowtail resting on Joe Pye weed.

The eastern tiger swallowtail – scientifically named Papilio glaucus – is a common neighbor in our Philadelphia area, but they are not strangers to many other parts of the eastern United States. They call the states east of the Mississippi River home, and even can be located in parts west of the river and in parts of Mexico. They are quite large among butterfly species, and when resting, their wingspan can reach up to 8 to 14 cm (3 to 5.5 in.) from tip to tip. Their coloring is a unique array of bright hues, and makes them quite recognizable.  Vibrantly yellow wings are intersected by black stripes (hence the ‘tiger’ part of the name), and blue edges with several red spots make up the bottom of the wings.

But as with all butterfly species, the eastern tiger swallowtail didn’t always look that way. As caterpillars, the swallowtail is a master survivalist. As young caterpillar, the strongest defense is their mimicry, or the ability to resemble something very different. In this case, the young caterpillar resembles bird droppings, a disguise that clearly allows it to get little attention. As the critters matures, it grows two black, yellow, and blue false eyespots on the thorax above and behind their true eyes, while its head is small and tucked low to the ground. This deceiving appearance can seriously fool a hungry predator, as a bird or small mammal may think twice about going after a critter with such big eyes. However, if the mimicry doesn’t work, the caterpillar has a backup plan in its set of bright orange glands on the neck. When touched, these glands produce a foul-smelling acid secretion that rubs off onto anything that seeks to grab it.

Eastern Tiger Swallowtail - Karen Singer

Eastern Tiger Swallowtail – of the FOUND exhibit by Karen Singer Tileworks

It is good to know that these insects have such effective means of survival, since they play a significant role in pollination. “Not all pollinators are created equal,” a North Carolina State University biologist found in 2015, identifying that butterflies, especially the eastern tiger swallowtail, played a large role in pollinating the flame azalea, a flowering bush native to Appalachia. The plant’s flower has an uncommon structure where the anther (male) and stigma (female) parts are widely separated, leaving the chances that a small bee could come into contact with both parts to spread pollen extremely low. However, the swallowtail with its wide wingspan can reach both parts of the flower, therefore becoming the main means of pollination for the plant. Without the specialized help of the butterfly, the flame azalea (and other plant species with similar structured flowers) might not be in existence today.

 

Sources:

“Who Pollinates the Flame Azalea?” In Defense of Plants, 7 June 2017, www.indefenseofplants.com/blog/2017/6/7/who-pollinates-the-flame-azalea.

Buchmann, Stephen. “Tigers on the Wind: The Eastern Tiger Swallowtail.” Eastern Tiger Swallowtail, United States Department of Agriculture, www.fs.fed.us/wildflowers/pollinators/pollinator-of-the-month/TigerSwallowtail.shtml.

“The Butterfly Effect: Insect’s Wings Key to Azalea Pollination.” NC State News The Butterfly Effect Insects Wings Key to Azalea Pollination Comments, North Carolina State University, 8 June 2015, news.ncsu.edu/2015/06/epps-butterfly/.