Saturday, July 13, 2013

Black Swallowtail - (Papilio polyxenes)

Black Swallowtail - female
The black Swallowtail is one of the most common swallowtails.  The black swallowtail is found throughout southern Canada, most of eastern and mid-Western United States West to the Rocky Mountains and  southwest into Arizona and northern Mexico.  Male and females can be separated by the appearance of the upper surface of their wings.  The upper surface is black with two rows of yellow spots, the males they are large and bright, and in the females smaller and lighter.  The area between the rows of spots in the hind wings of the female is a powdery in iridescent blue, but in the males.  It's much less prominent.  There is conspicuous red spot what a black bull's-eye on in a margin of the hind wings in an isolated yellow spot on the cost of the front wings.  The underside of the wings of both the male and female are virtually identical.  The caterpillars change colors as they grow older.  Younger larvae are mostly black, but with a white saddle, while the older larvae are green, with black transverse bands containing yellow spots.  Swallowtail caterpillars have a orange "forked gland" - the osmeterium, which they extend when threatened, and try to smear the predator with a chemical repellent.  The chrysalis can be either brown or green.  Single eggs are laid on the host plant.  The host plans are in the carrot family, such as Queen Anne's Lace, Wild Parsnip, Celery, Dill, Parsley, and Sweet Fennel.

Black Swallowtail - Caterpillar
Black Swallowtail - Caterpillar head showing the osmeterium
Black Swallowtail - Chrysalis