The Black Swallowtail Butterfly

The Black Swallowtail Butterfly

Papilio polyxenes

The Black Swallowtail Butterfly is native to much of North American. It is also called the American Swallowtail, Parsnip Swallowtail and Eastern Black Swallowtail. Its most common habitats are woodlands, rivers, grasslands, gardens and the Great Swamp.

The Black Swallowtail has black wings with 2 rows of yellow spots, which are larger and brighter in males. They have a blue area between the rows, the females being more prominent. Both have a red spot with a black bulls eye on the bottom of the wings. They have a wingspan of 2.5 to 4”. The male is slightly smaller than the female. They are agile and are fast flyers.

The adult diet is the nectar of thistles, clover, phlox and milkweed. They have a drinking straw called a proboscis, which stays curled up under the chin until the butterfly is ready to eat. When the adult butterfly comes out of the pupa (cocoon) it must assemble the proboscis, which is in 2 parts. They drink nectar from the flowers. They also drink from puddles so that they can consume minerals that they need which they don’t get from the nectar. This is called puddling. Butterflies may be seen in groups together when puddling. Butterflies taste with their feet.

The male creates his territory for mating and courtship. The female selects the male.

The Egg:

The females lay many pale yellow eggs. They are attached to a leaf that serves as food for the caterpillar. The leaf needs to be one that the caterpillar likes to eat. Favorite food plants for the Black Swallowtail caterpillar are dill, parsley, fennel, carrots, celery and Queen Anne’s Lace. The eggs turn dark gray before hatching. They hatch in 10 to 13 days depending on the temperature. The parent’s only involvement is in the mating and lying of the eggs.


The (larva) stage is when the caterpillar emerges from the egg. It eats the eggshell for protein and begins feasting on leaves. This is the time of feeding and growing. The young caterpillar has a black and white body. As it matures it turns green with black bands and yellow spots. The caterpillar absorbs toxins from the host plants, this serves as a protection as they do not taste good to bird predators. It has a gland (osmeterium) that produces a bad odor if it is threatened. This stage lasts 3 to 4 weeks.


The chrysalis (pupa) stage is the resting stage as the caterpillar transforms into a butterfly. During this time they do not eat or drink. The caterpillar spins a silk girdle around its middle in a loop to attach itself to a twig. Its feet are attached to the silk pad to secure it at its base. A hard protective case, the cocoon, also called the chrysalis, forms around the caterpillar. The color of the chrysalis is green or brown so that it is camouflaged from its predators. The chrysalis turns darker green just before the butterfly is about to emerge.


The chrysalis stage varies in length of time from a few days to a few weeks, if in a cold location it will hibernate for the winter, after which a beautiful butterfly emerges from the cocoon. The adult butterfly (imago) comes out of the pupa with their wings collapsed around their body they cannot fly. They have to pump fluid through the body and wait a few hours for the body to dry and harden before taking their first flight.

The average life span of the Black Swallowtail Butterfly is about 2 to 3 weeks.

Predators are small birds, spiders and insects.

Conservation Status: Least Concern

Black Swallowtail Butterfly: Top male, bottom female

Butterfly wings are actually transparent. They are made up of thin layers of protein. There are an average of about 18,000 species of butterflies.

Butterflies are cold blooded; they are immobile if the temperature is less than 55 degrees. They cannot eat or flee from a predator. They can also become over heated if the temperature is above 100 degrees.

Metamorphosis: The stages of development after birth, a transformation in form.

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