May is the month of Eastern Tiger Swallowtail (Papilio glaucus) & Tall phlox or garden phlox, (Phlox paniculata)

Eastern Tiger Swallowtail (Papilio glaucus) with its favorite Tall phlox or garden phlox, (Phlox paniculata)                        Cover photo by Tammra Banner, an EP resident and FHSP Board member

Fun facts:

  1. Eastern Tiger Swallowtail caterpillars at first look like bird droppings and later like reptilian monsters.  This super power of looking like something else to deter would-be predators is called Batesian mimicry. (See also January’s blog post on Hoverflies.)
  2. The larvae repose on a mat of silk they have made on a leaf. (1)
  3. Females can be yellow with black stripes and blue dots, or black with blue dots.
  4. Males gather in groups around puddles on the ground to ingest needed sodium ions and amino acids.  This is called “puddling.”
  5. The name, Papilio means butterfly in Latin. (Say that ten times fast and you will hear the sound of a butterfly in flight.).  In ancient Greece, the word for butterfly was psyche. Throughout western history and culture, the butterfly often symbolizes the soul of the departed. (2)

The Eastern tiger swallowtail lays round, green eggs singly on leaves of host plants, which are mostly native trees such as Sweetbay magnolias, white ash, tulip trees, birch, and wild black cherry.  The larvae have five instars, or phases, which start as brown with a white “saddle” that resembles bird droppings.  This is one way to fool the birds from picking them off!  The next method they use to fool predators, is to turn as green as the leaves with markings that look like eyes behind their natural heads.  When confronted by a predator, they look like a snake with glaring eyes and nose and mouth! (3). If the predator is bold and goes a little further, the caterpillar will produce a set of orange glands that look a bit like antennae but have the gift of a foul-smelling secretion that is wiped onto the enemy.

When the caterpillar gets ready to pupate, it turns brown again and crawls down the tree trunk onto the ground where it will create a brown chrysalis on the bottom of twigs or branches or even in leaf litter.  This is a good reason to leave your leaf litter in your garden.

The adult butterflies emerge after 9-11 days, or they overwinter.  They are large with a wingspan of about 3 to 5 ½ inches across.  The male is yellow with four black stripes and a black band around the edges of the wings that contain yellow dots. The female is either yellow with black stripes and some blue and red scales on her bottom wing edges, or all black, again with the blue and red scales.

While the Eastern tiger swallowtail visits a wide variety of nectar plants, males can be seen in groups sipping from mud puddles, carrion, and urine.  Recent studies have shown that “amino acids and electrolytes, when added to the sugar diet of adults, significantly increased the virility & reproductive success of P. glaucus males.” (3)

One flower that attracts Eastern tiger swallowtails is garden phlox.  This perennial is native to Eastern US, and its showy blooms of purple and pink (sometimes white) on  3-6 foot tall stems are a favorite of butterfly gardeners.

We hope you enjoyed learning about Papilio glaucus. If you would like to enter our free raffle, click on this link and enter your name and email:


For further reading (or watching)

Next month, look for our article on the charismatic Monarch butterfly!