One of my favorite things to do in Phoenix is to visit the Desert Botanical Gardens, especially when they have their annual Butterfly House open. My friend Lynda visited us from Ohio a few weeks ago, and we went to see the Butterflies.
The one above is a Pipevine Swallowtail.
Here are Zebras and a Painted Lady.
More Zebras, a Julia, and another Painted Lady in the top left.
A white Sulfur possibly? The Identification Guide that I picked up didn´t show one that looked quite like this. So if there are any butterfly experts out there, please feel free to correct the ID.