Thanks, Steve. I suspect we have both London Plane trees and Sycamore trees in the Twin Cities area. Do I need to distinguish between them? I will look for cats. In the meantime I will take this back to the Genus level as I should have in the first place.

I think American Sycamore might be out of range but to answer your question, both trees are host to H. harrisii. Unless there's a London Plane within walking distance, I'd guess that H. tessellaris is most likely. H. harrisii is not known in your area but it seems to be where ever London Plane has been introduced. In any even, genus would probably be better.

Thanks. It's rare one can get an open-wing shot.