Eastern Black Swallowtail

Papilo polyxenes

Jim Brock

Copyright, Randy Emmitt, www.rlephoto.com

The Eastern Black Swallowtail is a common swallowtail butterfly, often confused with the Pipevine Swallowtail or female Tiger Swallowtail.

Both male and female Eastern Black Swallowtails are bluish-black with yellow spots on the wings. They also have two orange eyespots with black dots in the middle.

The male has a yellow band on the hindwings with a blue cloud under it. The female has a row of yellow dots above a blue band. It's easiest to remember that males have more yellow, and females have more blue.

Copyright, Jay Cossey, http://www.images.on.ca/JayC/

Copyright, Randy Emmitt, www.rlephoto.com

Eastern Black Swallowtails take flight in late March and continue until September. After mating, the female lays small yellow eggs on a host plant. A host plant is the plant that the caterpillars eat. The caterpillars, when they hatch, are brownish-purple and white. They are small and look like bird droppings. This probably helps camouflage them. As the caterpillars get older, they look like the picture above. They are two inches long, leaf-green with white, black bands, and yellow spots.

The main host plant for this butterfly in the wild is Queen Anne's Lace, but they also eat garden plants in the carrot family, including carrots, parsley, dill, and fennel.

Once a caterpillar is old enough, it will form a chrysalis like the picture to the left, usually brown or green.

This animal will overwinter in the chrysalis, meaning it won't hatch into an adult until Spring. The adult will drink nectar from many different flowers, including milkweeds, thistles, Red Clover, and Purple Coneflower.

The Eastern Black Swallowtails will search open spaces, such as meadows, gardens, banks of streams and ponds, marshes, and roadsides in search of nectar and mates. They usually flutter around, but when they are disturbed they fly straight.

This butterfly is a mimic, meaning its pattern copies another animal. Its cousin, the Pipevine Swallowtail is poisonous to many predators. By copying the Pipevine Swallowtail, the Eastern Black Swallowtail gains protection from predators, even though it is not poisonous. This animal is most often eaten as a caterpillar.

Additional Media

Eastern Black Swallowtail Caterpillar Changing Into a Chrysalis
Link to Time-lapse Video*
Eeyore's Thistle Patch
Butterfly Anatomy Diagram
Link to Printable Page

* Click the link above to see a time-lapse animation of an Eastern Black Swallowtail caterpillar changing into a chrysalis. A time-lapse is when a video is "sped up." The animation you will see actually took 27 minutes to happen, but the photographer "fast forwards" so you can see what happens in only a few seconds.

Relationships in Nature:


Queen Anne's Lace

Red-winged Blackbird

Queen Anne's Lace

Pipevine Swallowtail Mi

Common Milkweed

Pennsylvania Firefly

Black-eyed Susan Po

Bull Thistle

Five-lined Skink

Bull Thistle Po

Red Clover

Green Darner

Red Clover Po

Black-eyed Susan

Goldenrod Spider

Common Milkweed Po


Chinese Mantid

Fiery Searcher

Striped Skunk

Relationship to Humans:

Like all butterflies, the Eastern Black Swallowtail is a good pollinator. As it visits plants, looking for nectar, it spreads pollen from flower to flower so the plants can grow. This is helpful to people if the plants are desirable, but pesky if the plants are considered weeds.

Some people consider the caterpillars of this butterfly to be a pest, since they eat parsley, carrots, and other garden plants.

Many people enjoy butterfly-watching and collecting, and the Eastern Black Swallowtail is considered by most to be a handsome specimen.


Papilio polyxenes


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