I normally prune mine in the spring to about six - 12 inches from the ground. This yeat I didn't get around to pruning, but I think it has a much nicer habit when you do prune it. This year's plant is much more open and wild looking. And about twice as wide as other years!

Buddleia should continue to bloom until a hard frost. (I'm near CIncinnati and they last till Halloween at least) Deadheading/trimming the scraggly stuff should result in a flush of new blooms in a few weeks. As long as they get enough water, they should be just fine.
I try to deadhead mine every couple weeks - just love the butterflies and hummingbirds they attract.

You can't prune them hard this late in the year, but you might try next spring. They're not fully hardy where you are--at least with normal winters--so it's hard to tell how they'll respond after years of no pruning.

Yeah, I would wait until spring, too. It's just too late to risk it, the roots will need all of the carbs they can get going into the winter.

I'm in z6 and in the past I lost a few Buddleia, but I've kept others now for over 7 years. I never prune hard except in spring. I do however deadhead constantly and it keeps mine blooming right up until frost.

in livonia.. i learned to consider these short lived plants ... living and prospering only until mother nature took them away ... one bad winter..

relish it while you can ... in whatever form it is in.. and what they said as to pruning ... the only one that got as big as you described.. didnt come back the next spring ... who knows if it was me or winter.. that did it.. for all i know.. i pruned it down that fall prior. . lol ...

ken