Black Swallowtail

The **Black Swallowtail** (*Papilio polyxenes*) is a species of butterfly. It is also called the **American Swallowtail** or **Parsnip Swallowtail**. It is found throughout much of North America.

## Description
The Black Swallowtail has a wingspan of 6.7 to 10 cm (2.7 to 4 in). The upper side of the male's wings is black. There are two rows of yellow spots along the edges of both wings. There is a small area of blue on the bottom wing between the two rows of yellow spots.On the bottom edge of the bottom wing, there is a red spot with a small black dot in the center.

## Taxonomy
The Ozark Swallowtail (*Papilio joanae*) and the Black Swallowtail were once thought to be the same species. Felix Sperling did an analysis of the Ozark Swallowtail's DNA. He suggested that even though the Ozark Swallowtail looks exactly like the Black Swallowtail, it is actually more closely related to the Old World Swallowtail (*Papilio machaon*).

In North Dakota and southern Manitoba, the Black Swallowtail is thought to breed with the Old World Swallowtail. These hybrids are called Kahli Swallowtails.

The Desert Black Swallowtail (*P. p. coloro*) is a subspecies of the Black Swallowtail. It is found in southeastern California, southern Nevada, and western Arizona. It is similar to the male Black Swallowtail, but it has more yellow and the sexes look the same. It is rarely (unusually) found in forests or woodlands.

## Flight period
The Black Swallowtail is seen from May to June in Canada. It is seen from June to August in the Colorado Mountains. In the eastern part of its range, it is seen from April to October and from February to October in Florida.

## Adult food sources
Here is a list of food sources for the Black Swallowtail:

* *Asclepias incarnata* – Swamp Milkweed
* *Asclepias syriaca* – Common Milkweed
* *Asclepias tuberosa* – Butterfly Weed
* *Barbarea vulgaris* – Winter Cress
* *Cirsium discolor* – Thistle
* *Dipsacus sylvestris* – Teasel
* *Echinacea purpurea* – Purple Coneflower
* *Medicago sativa* – Alfalfa
* *Syringa* sp. – lilac
* *Trifolium pratense* – Red Clover
* *Vernonia* sp. – ironweed
* *Zinnia* sp. – zinnia

Males will also come to damp soil and mud to feed on minerals and moisture. This is called puddling. In a lab test, females laid a total of about 200 to 430 eggs. They laid about 35 to 50 each day.

### Caterpillar
The caterpillar will eat the leaves and flowers of the host plant. It makes no nests. The young caterpillar is black. It has a white spot in the middle of its body. This spot is called a saddle. It mimics a bird dropping. The older caterpillar is green. It has black bands with orange spots in each of the bands. The caterpillar has a special organ called an osmeterium. It is an orange, bad-smelling organ. It is shaped like a snake's tongue. It is kept behind the inside of the head. The caterpillar  it to scare predators away. The caterpillar will reach a length of 5 cm (2 in). The Ozark Swallowtail caterpillar is similar to the Black Swallowtail caterpillar. It is usually greener, and the black bands are usually thinner.

### Chrysalis
The chrysalis hangs . There is a silk thread around the upper part of the chrysalis. This thread is called a girdle. The chrysalis is either brown or green. The Black Swallowtail will hibernate as a chrysalis.

File:Egglaying.JPG|A female laying an egg
File:Swallowtaileggs.JPG|Eggs
File:Black Swallowtail Papilio polyxenes Caterpillar Parsley 2571px.jpg|A young caterpillar
File:Black Swallowtail Papilio polyxenes Closeup.jpg|An older caterpillar
File:Black Swallowtail osmeterium, Megan McCarty123.jpg|A caterpillar showing part of its osmeterium
File:Black Swallowtail Papilio polyxenes Chrysalis.jpg|Chrysalis
File:Black Swallowtail Chrysalis Megan McCarty33.jpg|A chrysalis ready to hatch

## Host plants
Here is a list of host plants that the Black Swallowtail caterpillar feeds on:

* *Anethum graveolens* – Dill
* *Apium graveolens* – Celery
* *Berula erecta* – Water Parsnip
* *Cyclospermum leptophyllum* – Slender Celery
* *Daucus carota* – Queen Anne's Lace
* *Daucus pusillus* – American Wild Carrot
* *Foeniculum vulgare* – Anise (also called Fennel)
* *Pastinaca sativa* – Parsnip
* *Petroselinum crispum* – Parsley
* *Thamnosma montana* – Turpentine Broom (used by the Desert Black Swallowtail only)

## References