Around here chamisa is popular with several of the native wasps & bees.
You use the phrase " butterfly type" yet mention "swarming and buzzing". Sounds more like hymenoptera behavior instead of lepidoptera.

You're right, now that I think about it, they acted more like bees but didn't fly anything like wasps do around here. They had sort of tear-drop shaped wings that were very opaque and velvety deep black but much wider than a wasp's wings. Their heads were black on the very tip, then bright red with a sort of shoulder part that was yellow with black antennae and black legs. There was a blooming Russian sage close by and they completely ignored it and everything else that was blooming and just seemed frantic over the Chamisa. I tried to post a picture but it was too many DPI or a Jpeg or something and it wouldn't post.

Now I'm intrigued.
Your comment on the insects ignoring the Perovskia yet swarming over the chamisa made me think they aren't actively pollinating. There are paper wasps that come close to matching the description you gave. These gals really work Fall blooming plants such as goldenrod and chamisa for those final few larvae and insects of the year. Gotta feed the kids back at the nest you know.
Did you try to post the photo directly from your 'puter or did you go through an online photo site, i.e. Flicker, Photobucket?
Would love to see a photo of the insects and your blooming chamisa. Great plant!