Mimics

This afternoon we got home from church and I saw a very large dark-colored swallowtail nectaring on my Garden Phlox.

It has been a while since I was completely fluent in butterfly identification skills. At first it seemed to be a Spicebush Swallowtail, or maybe a Pipevine Swallowtail.

But the underside just didn’t match up with either of those. This butterfly was pretty plain on the underside, instead of having heavier white and orange markings. Plus, it was just so huge!

I emailed a very knowledgeable friend, then before he responded I noticed this butterfly does not have a spotted abdomen. I googled this detail and discovered this is the dark morph of the Easter Tiger Swallowtail.

I do occasionally see Eastern Tiger Swallowtails in my garden, like this one nectaring on the very same phlox three years ago.

You can see why I didn’t immediately think of the Eastern Tiger Swallowtail when I saw this dark butterfly today! Although the size was a clue, the coloring is quite different.

A standard female does have the blue patch at the base of the top side of the wings, like the dark morph. This is one I saw at the Bill Roston Native Butterfly House four years ago.

From what I read, the black morph female of the Eastern Tiger Swallowtail only occurs in the southern part of its region, where it overlaps with the range of the Pipevine Swallowtail. The Pipevine Swallowtail is poisonous to predators due to its larval food plant, Pipevine. This means it is advantageous for other butterflies to have a similar look. While birds are avoiding Pipevine Swallowtails, they avoid other black and blue butterflies like the black morph of the Eastern Tiger Swallowtail, the Spicebush Swallowtail, and the Red-Spotted Purple, while they’re at it.

Spicebush Swallowtail – picture from Wikipedia
Red-spotted purple – picture taken at my home three years ago.

The Red-spotted Purple actually has a completely different look in its northern range (where the Pipevine Swallowtail doesn’t roam). In the north it is called the white admiral.

White admiral – picture from Wikipedia

It is so interesting that the Creator programmed into the genetics of these butterflies the ability to mimic the Pipevine Swallowtail! Truly amazing.

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