Black Swallowtail

Black Swallowtail, one of our most common and familiar butterflies, easily confused with several other dark swallowtail species. The undersides of males and females are similar. The caterpillars are more often seen than adults. The caterpillar has a special gland called an osmeterium that emits a foul odor when the caterpillar is threatened. The orange osmeterium looks like a forked snake tongue.

Caterpillars also ingest oils from the host plants of the carrot family; the foul taste of the chemical in their bodies repels birds and other predators. The chrysalides of the Black Swallowtail can be green or brown, depending on the color of the surface to which they are attached. This form of camouflage keeps them hidden from predators. The adult butterfly is thought to mimic the Pipevine Swallowtail, which is distasteful to predators.

They seemingly appear spontaneously on plants in the carrot family (Umbelliferae or Apiaceae) such as fennel and parsley. The Black Swallowtail has a wingspan of 8 to 11 cm (3.1 to 4.3 in). The upper surface of the wings is mostly black. On the inner edge of hindwing is a black spot centered in larger orange spot. A male of this species has a yellow band near edge of wings; a female has row of yellow spots. The hindwing of the female has an iridescent blue band.

Posted in: B,Black Swallowtail,Papilionidae