Tuesday, November 25, 2008

A New Type of Butterfly (for Judi)

The Polydamas Swallowtail (also called the Gold Rim Swallowtail) does not actually have a swallowtail, making it "the swallowtailless swallowtail." Go figure. Judi has Polydamas caterpillars feeding on a Dutchman's Pipevine along the back fence. The Polydamas is unique among butterflies in that the female lays eggs in a cluster, rather than singly and spread out, and the caterpillars travel together in little caravans as they feed and grow:

A herd of young polydamas caterpillars

One theory is that by massing together the Polydamas caterpillars look like something big and mean and are less likely to be taken by predators. Here's a group of larger ones grazing shoulder to shoulder:

Some larger caterpillars grazing along together

These caterpillars get really, really big. Also really, really ugly:

They get really, really big; and really, really ugly

When the Polydamas caterpillar forms a chrysalis, it looks a lot like a dead and dried leaf. This little strip of vine features a dead leaf at the top, Judi's first Polydamas chrysalis in the middle, and another dead leaf at the bottom, so you can see how realistic they look:

Polydamus chrysalis and two dead leaves

This is the chrysalis up close:

Polydamus chrysalis

Judi has three of these Polydamas chrysalises in protective custody at this time, and a bunch more caterpillars still munching away on the vine out back. I hope to have pictures of the emerged butterflies for you in a later post.



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