Twikipedia, they’re supposedly seen across the U.S. but I can’t remember the last one I saw that wasn’t in some kind of “butterfly zoo.”
Another unique-to-this-area insect: Lightening Bugs / Fireflies. We used to see them every summer when I was a kid in NY, but I haven’t seen one in so long. I don’t believe there are any in Utah at all. I was really psyched to have Rachel and Zachary see them and chase after and even catch a few. (We let them go after a few minutes of watching them up close).