Swallowtail Butterfly In The Zinnia Patch

by Kay Novy

Title

Swallowtail Butterfly In The Zinnia Patch

Artist

Kay Novy

Medium

Photograph - Photography

Description

A beautiful yellow tiger swallowtail butterfly in my colorful zinnia patch. I always plant a package or two of zinnia seeds in my gardens, for I know sooner or later the butterflies will find them.

Swallowtail butterflies are large, colorful butterflies in the family Papilionidae, and include over 550 species. Though the majority are tropical, members of the family inhabit every continent except Antarctica. The family includes the largest butterflies in the world, the birdwing butterflies of the genus Ornithoptera.

Swallowtails have a number of distinctive features; for example, the Papilionid caterpillar bears a repugnatorial organ called the osmeterium on its prothorax. The osmeterium normally remains hidden, but when threatened, the larva turns it outward through a transverse dorsal groove[3] by inflating it with blood.

The forked appearance of the swallowtails' hind wings, which can be seen when the butterfly is resting with its wings spread, gave rise to the common name swallowtail. As for its formal name, Linnaeus chose Papilio for the type genus, as Papilio is Latin for 'butterfly'. For the specific epithets of the genus, Linnaeus applied the names of Greek heroes to the swallowtails. The type species: Papilio machaon honoured Machaon, one of the sons of Asclepius, mentioned in the Iliad.

In Papilio glaucus (Eastern Tiger swallowtail), Y-linkage determines whether the females are either wild-type (yellow and black) or melanic (dark melanin replaces the yellow background).[14] This genetic difference stems from the fact that melanism is controlled by a single gene, which controls the level of dopamine in the organism. During development, the enzyme BAS, which assists dopamine in producing the yellow pigmentation, normally found on the wings' background, is suppressed. Without the pigmentation, the butterfly appears mostly black (the melanic form) and is a Batesian mimic of Battus philenor, the Pipevine swallowtail. There are also Papilio glaucus that are not wholly black; several possess an intermediate "sooty" color and are sensitive to temperature.

The different polymorphisms (wild-type, melanic, and the 'sooty' intermediate) depend upon the geographical distribution and abundance of its mimic, the Battus philenor, whose wing color varies depending on its geographical location. In order to be successfully confused for the B. philenor by predators, the Papilio glaucus's background wing color matches that of the B. philenor residing in the same regional area. Studies support this theory; in the southeastern United States, the relative abundance of melanic females has been found to geographically correlate with B. philenor.

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November 17th, 2014

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