I've linked below the range map for them.

At my first house, I used to get ZSTs flying around every year even though I had zero pawpaw and I'm guessing there was zero anywhere near me. Now around 5-6 miles north of that house, I have an acre, 3 pawpaws, pawpaw in the forest behind me, and pawpaw across the street. With all that pawpaw, I've seen one ZST and that was in 2005.

In places where I've seen ZSTs in large numbers, large open spaces/meadows were in the area. My first house literally had I-71 in the backyard. That observation is weird to me since pawpaw is usually an understory tree so the ZSTs have to fly into woods to find their hostplant. Typing that reminded me that I see ZSTs mate out and about. I'm used to male butterflies patrolling for mates around hostplants. ZSTs are different.

KC

Here is a link that might be useful: Zebra swallowtails

There are many different types of paw paws. Do you know what kind you have? I have many different types in my yard and have seen one zebra swallowtail in ten years or so. I keep trying to see if different types of paw paws will attract them. The ones native to where I live in Central Florida grow very slowly.

I see the Zebras in a park about five miles from my home, but they don't visit my yard.