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| Black Swallowtail, Papilio polyxenes. All photos by Camille Paige |
The black swallowtail, Papilio polyxenes, is a large native CO butterfly with distinctive adult and larval (caterpillar) forms. The adults are striking butterflies with yellow spots lining the wings and blue spots and a “tail” on on the hind wing. Females can be distinguished by their more pronounced blue scales and smaller yellow spots.
The
adult female lays yellow eggs on plants of the Apiaceae/Umbelliferae family
(also sometimes referred to as the parsley or carrot family.) Eggs develop for up
to 10 days before hatching into a tiny, spiny reddish and black caterpillars with pale “saddlebag” coloration about halfway down its length.
The caterpillar quickly gains mass as it feeds on the host plant, becoming a beautiful black, white, and neon green striped specimen.
As it reaches full
size, it will typically find a sturdy stem, branch, or other vertical scaffold
to support formation of its chrysalis. Depending on the time of the season, the
caterpillar will undergo metamorphosis over the following 10-20 days or
overwinter to emerge in the spring. You can provide overwintering habitat to
this species and many others by waiting to prune back dead growth until mid
spring.
I plant and allow dill to bloom and reseed throughout my garden to support these guys and look forward to their visits every year. Additional host plants for the caterpillars are carrots, parsley, and fennel. Adults feed on nectar from flowers and some favorites include showy milkweed (Asclepias speciosa), purple coneflower (Echinacea purpura), and blanket flower (Gaillardia aristata).
Fun fact! The caterpillars also glow under backlight.