Eastern Tiger Swallowtails at Fort AncientYesterday I slipped out of work early and headed up to Fort Ancient. I was hoping to find a small flock of American Goldfinches as they worked the thistle-laced meadows looking for silky thistledown to take back to their nests, and I wasn't disappointed. As I walked toward the meadow next to the museum I could hear them, happy and chatty in their flight, but butterflies were everywhere, and their soft and gentle movements soon stole my attention away. From a distance, the butterflies looked fresh and new, but behind the camera lens I could see their wings were weathered, tattered and torn. (Click here for photos of goldfinches tugging out thistledown last September at Fort Ancient.)
The thin membrane of a butterfly's wings is covered in tiny scales arranged like shingles on a roof. Not built for long life, butterflies lose scales every day as their wings touch leaves, flower petals and other butterflies. Their color fades as the powdery scales drop away.
Even though the darks are a bit faded and chunks have been torn from its wings, this swallowtail's iridescent blue scales are still vibrant and beautiful. Two types of color show in a butterfly's scales--pigments, such as melanin, create black and other deep shades, while a microscopic open lattice structure creates reflective surfaces that form the iridescent blues and greens (similar to the structural color and pigment in hummingbird feathers).
This Eastern Tiger Swallowtail looks like it's been through a scrape or two. I wonder how many birds have nipped at its wings or how many buffeting winds it's dodged. Butterflies can fly with as much as 70% of their wings missing!
...since butterflies have no means of self-repair, they can become ragged within a few weeks and many species die within a month. (There are exceptions, some species overwinter in a dormant state and can live up to a year, and, of course, those amazing migrating Monarchs can live about eight months).
Female Eastern Tiger Swallowtails also come in a dimorphic dark form (shown in the upper right). Dark form females mimic Pipevine Swallowtails. While caterpillars, Pipevine Swallowtails munch on pipevine leaves, which are toxic. The result is a foul-tasting butterfly that birds avoid. (Click here for the Pipevine's story...)
A fresh Tiger Swallowtail (left) shares a thistle plant with two other swallowtails of varying ages. There were easily 30 or 40 Eastern Tiger Swallowtails in this little meadow, all nectaring on the thistle blossoms while goldfinches joined them here and there, plucking thistle down from spent flowers...
...and taking it back to their nests.