Zebra Swallowtails

Zebra Swallowtails mating

Pawpaw blossom - Mark Bower

Zebra swallowtail butterflies were fluttering all over Bull Mills the last week preparing to start a family.  Unlike the mating picture above from last summer, the host plant leaves haven't opened yet, but the males were out patrolling to be ready.  As the week rolled on the pawpaw buds opened and the first tiny leaves started to appear.

Zebra caterpillars can only eat leaves of Asimina species, the pawpaw.  We have it scattered along the valley floor as well as a patch high up on top of the ridge.

Spring comes at different times at Bull Mills.  On the ridge tops the pawpaw are in full bloom and their leaves are emerging.  Down in the valley where the nighttime temperatures are 6 to 8 degrees cooler, the flower buds are closed and the leaves haven't opened up.  Meanwhile the zebra swallowtails have gotten their message from the length of the daylight and are patrolling both areas.

I settled in at the grove on the ridge, determined to photograph a female laying an egg.  Males patrolled restlessly less than 3 feet above the forest floor and after an hour, suddenly a zebra flew up and held a leaf for a few seconds, moving on to another as I chased it, never getting it into focus.  Seven stops, each on a different tree and then it disappeared.



This time of year they only deposit eggs on the tiny emerging one inch leaves.  With a dense grove of two dozen trees it is nearly impossible to find an egg this time of year unless you see it laid.  I found this one seconds after it was attached.  Soon a tiny caterpillar will emerge to chew on the moist and tender leaves.

Different instars, last one on the right - Bioweb

As the caterpillar grows it will split out of its tight skin, emerging in a larger and looser skin.  Each stage will be darker until the 5th instar when it will form its chrysalis.

A day later I sat in the pawpaw grove for two hours and was finally rewarded by an obliging female zebra which gave me just enough time to focus and shoot.

Attaching the egg, a three second stop

Pawpaw blossom - Mark Bower

Like most other plants with dark purple to brown blossoms, the pawpaw flower has a smell of something dead, attracting flies and beetles looking for carrion.  They will then be fooled again with the next blossom, unwittingly carrying pollen to another tree and life goes on.
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Detailed information on the zebras, Eurytides marcellus, is at this University of Florida entomology site.