Mike Powell

Yesterday was a beautiful spring day and I was delighted to capture this image of a Zebra Swallowtail (Eurytides marcellus), one of my favorite butterflies, at Occoquan Bay National Wildlife Refuge. I chased after this hyperactive butterfly and luckily was close enough to get a shot when it landed for a split second. I love the touches of red and blue on this mostly monochromatic butterfly and its distinctive long “tails.”

As I was doing a little research on this butterfly, I discovered that the Zebra Swallowtail has two seasonal forms, one occurring in the spring and the other in the summer. According to Wikipedia, the spring forms are smaller, more white, and have short, black tails with white tips. As you can see from the first photo below, yesterday’s Zebra Swallowtail was a spring form butterfly.

Summer forms of the Zebra Swallowtail are larger, have broader black stripes, and longer, black tails with white edges. For the sake of comparison, I reprised a photo from a 6 September 2021 blog posting. The butterfly in the second photo, a summer form butterfly, indeed looks darker than the one in the first photo and there are noticeable differences in the shape and coloration of the tails.

© Michael Q. Powell. All rights reserved.