They are leaf cutter bees.

http://www.ext.colostate.edu/PUBS/INSECT/05576.html

Not sure what you can do, They usually don't do too much damage.

Ditto - they usually don't do enough damage to warrant any kind of control. And, you don't want to use chemicals to dispel them, do you? That would adversely affect your habitat for the butterflies.

I'm putting Buford's link below so you can click on it to read it without copying into your browser.

I just noticed it was an article by W.S. Cranshaw. He has published a book on Insects. I have that big ole book myself and it comes in very handy. I'd highly recommend it for ID'ing insects, common and not so common, in the garden.

Susan

Here is a link that might be useful: Buford's Link

Thank You all so much, we will just leave them alone, seems the benefits definitely outweigh the damage.
Sandee

It s a matter of opinion about damage they have eaten most of the leaves from my young plumbago! I would rather they "buzzed" off.