Well, about an hour after I published today’s blog post on the painted lady migration, I received an email response from Royce Bitzer (Iowa State University) which answered some questions I’d sent him earlier in the week. I’d waited for his responses before posting, but finally decided to just go ahead with the information I had.
Dr. Bitzer provided one main piece of information that was different from what I’d originally said in my post, which is that there isn’t any evidence that the big super bloom of wildflowers in California spurred the migration. He was surprised by that, but said that based on reports from the Las Vegas, NV and Albuquerque, NM areas, this year’s high numbers of migrating butterflies likely came from places near those reports, rather than from further west in California.
A little bit of additional information from Dr. Bitzer… There is no evidence that painted ladies (or red admiral butterflies) can overwinter around here, so the butterflies we see during the summer get here through migration. The painted ladies in my backyard now are likely a combination of butterflies that hatched out here (descendants of migrants) and others that are passing through from further north. He’s been trying to track reports of movement over the last several weeks, and it appears that the big southern migration started over Labor Day weekend (Sept 2-4) when a cold front swept butterflies out of Canada and into the Dakotas. Since then they’ve been moving further south, reaching Iowa and Nebraska. They are joining up with already-present large populations that had hatched out here before the migrants arrived.
Anyway, I apologize for a second post on this topic, but I wanted to be sure I was providing the best information I could. The original post has now been edited to make it more correct.
The Prairie Ecologist 
I am confused: Did you mean TO the South rather than FROM the South? Canada to the Dakotas sounds TO the South. I too have wondered: are they doing tag-team migration, like Monarchs, & how far are they going? How long will one individual live? So much to learn!
Sorry, you’re right – that was confusing. I meant that they’d originated in the desert southwest, as opposed to being year-round residents here. This is what I get for trying to write a quick post… shoddy writing! Thanks for pointing that out. I’ve edited my supplemental post to make it less confusing. …Good grief… : )
Thanks for the update. Nature sure can change the routine.
Here at Prairie State Park in southwest Missouri, we have been seeing thousands of the Painted Lady as well. Certainly a first for me.
Loved the details! What can you tell us about the American Lady? I usually see a few of them but have looked all summer and don’t think they are included in this population. I also wonder if there are a lot of American/Painted Lady hybrids, as I am not sure whether the ones with 2 big eyespots but other small spots are American or Painted. I am in Washington County.
Hi Linda, I don’t honestly know very much about them. Here is a nice page of information on the American lady and other Vanessa butterflies. http://vanessa.ent.iastate.edu/species.html
Thanks for your reply. The iastate source has the best picture of dorsal (open-wing) side of any source I have seen, and that is how they often seem to rest. For the record, I did see a painted lady twice very early in April this year, and thought then that something was up. My suspicion is that they are hatching further north than previously. So true that there are many simple details that we don’t yet know. I really appreciate your blog and your Nebraskaland articles.
I have been wondering the same thing–about American x Painted hybrids, as I found several with 4 eyespots but thhe white dot in the orange cell. Also, when they first started showing up in early spring, both species were present.
This is very interesting, as we had more here in Nova Scotia this fall than I had ever seen. They were partial to the sedums. I counted 14 on one plant one afternoon. I think it was late September, and could say for sure if I could find the photo. Love your writing.