Unusual coloring on Eastern Tiger Swallowtail
Location: floyd county, VA
August 7, 2010 3:32 pm
i was recently browsing your site, and was fascinated by Your feature the Tiger Swallowtail Gynandromorph.
Today while taking pictures of the butterflies on my butterfly bush i noticed one of the Eastern Tiger Swallow tails, had unusual coloring. It is the typical yellow, with stripes, but also has patches of dark. i’m curious as to whether it was a normal variation in pattern, or possible a form of mosaic Gynandromorph. Would love any info. i’ve been watching swallowtails for many years, and have never seen one quite like this.
Thanks for sending us your photo of a transitional morph of a female Tiger Swallowtail. Most female Tiger Swallowtails are yellow with black stripes, but a small percentage are dark morphs, with the yellow ground color appearing very dark. It is sometimes difficult to make out the stripes unless the light shines through the wings. Even rarer are transitional morphs like yours, where the female is not truly light or dark, but an intermediary phase between the two typical morphs. These transitional morphs exhibit varying degrees of coloration and markings. We have several examples posted to our site from previous years, including a mounted specimen from July 2010. The gynandromorph is a real rarity, not just among swallowtails, but among all butterflies or insects for that matter. The bilateral sexual division, where the left half of the insect is one sex and the right half the other sex is especially unusual, though in many insects that do not exhibit extreme sexual dimorphism, many examples may go unnoticed. The gynandromorph we just posted is an extreme example because the coloration difference between the left and right halves is so extreme. We suspect gynandromorphs are infertile.
Thank you so much for your reply and information. It’s always exciting to see a new or unusual butterfly and be able to identify it! Thank you again!