Friday, October 14, 2005


Pipevine Swallowtail larva

Phoresis. That's what this caterpillar was experiencing as I photographed him. I found him tearing across my porch at top speed, and nudged him onto my finger and then on to the pear tree for a short photo session. He was in a hurry. When these large caterpillars are about to pupate, they become restless, leave the plants where they've been feeding and start looking for a safe place to dissolve into a morphogenic soup and reassemble into a winged creature. Phoresis is movement from place to place, as in electrophoresis (where molecules migrate differentially through a gel in response to electrical current).

I was particularly pleased to see this fellow, because he answered a question that's been on my mind since I moved here: Are those irridescent butterflies I see so often Pipevine Swallowtails or Spicebush Swallowtails? I haven't been able to find either Aristolochia or spicebush anywhere around here, but the butterflies are abundant. The caterpillars of the two species are nothing alike, and this fellow is definitely a Pipevine Swallowtail. That's Battus philenor, (Linnaeus) as near as I can tell. (I got it off the Internet, not from an authoratative text.) While trying to figure out the correct genus name (My old books here at the house use Papilio.), I found these interesting Web sites.

Addendum: After I posted this, I saw that Fred of Fragments from Floyd had posted his own swallowtail larva photo. His caterpillar sat tight. Evidently it was done with phoresis.

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