August 15, 2025

When I think of a Tiger Swallowtail (Papilio glaucus), I automatically think of a yellow butterfly with black stripes.

But there are females of that species that mimic Pipevine Swallowtails (Battus philenor) and are mainly black. Plants in the genus, Aristolochia, that are in abundance in the south, are used as the host plants of the Pipevine Swallowtail. Those host plants give the caterpillars and butterflies an extremely bitter taste. Mimicking the Pipevine Swallowtail gives the female dark morph Tiger Swallowtail protection, since those Swallowtails are often avoided because of their unpleasant taste.

The dark female Tiger Swallowtail at times shows just a hint of the tiger stripes. Very subtle as you might be able to see in the photo above.

When it comes to mating, seems the males prefer the yellow females but the black morph is less attractive to predators so there are more of them around.

Yellow Tiger Swallowtails can be either male or female. The dark morph is always a female. Yellow offspring are produced by yellow females and dark offspring are produced by dark females.

Nature is amazing.

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