Ann, I think the caterpillar vaccine just came out last year so it's really new.
I definitely agree about regional differences. I think it's really important to get a field guide for your area, if possible. But it's also good to read national or even worldwide butterfly books because you can learn a lot from them, too. The caterpillars you're going to raise are going to be local so it makes sense to learn them first. I was at a favorite local nursery for a butterfly talk a few years ago and the owner had caterpillars on display eating their host plants. Well, she went on to talk about each of the caterpillars and held up the Eastern Black Swallowtail caterpillar and called it an Anise Swallowtail. And they do look exactly alike and feed on many of the same plants. But (big but here), the Anise Swallowtail lives west of the Rockies! I didn't have the heart to correct her in front of like 50 people. Of course, now that I have no shame (thank you Klonopin!) I would totally do it. But in a nice way. I'm still nice, even if I have no shame. I'm sure she looked in some North American book and the caterpillars looked the same so she assumed that was the right one. But if she had looked in a Florida book she would have known the difference.
And of course, there are regional differences like how Viceroys will imitate Queens with their coloring in certain areas (like where I live). For me, it's weird to see an orange Viceroy. Also, it might be my wishful thinking, but I think the Red-Spotted Purples were more blue in WV. Maybe I just got an exceptionally nice one. It wasn't a fresh one as it was a little tattered, but it was so pretty! And some areas get more of the female dark-form Tiger Swallowtails while some areas get the regular yellow ones.
