Sounds like Whiteflies.
Wash them off with dish soap and water, then rinse. The soap won't hurt your plants. Don't rub or damage the stem.

Annie..I think you are right. I saw evidence of it on Azeleas next to it and I sprayed two kinds of insect spray that said it could be used for Whiteflies. I will try the soap method next. I have to go back to some notes from a gardening coach that I had a consultation with last year or year before. Something was on the azeleas then.

Just dug up my one and only Emerald Blue creeping phlox and transplanted some of it where I had dug out a large mum. It was 100 plus here yesterday and it's heading that way again. I've just come in to cool off and rest. Got to find a place to plant the rest of that creeping phlox. I'm pulling out small columbines as they are getting invasive. What's left will reseed I'm sure and I have others planted elsewhere. Getting company, need to "read up" a bit. People from Pa.Dutch country will know what that means.

Pippi, I'm Pa. Dutch, but too far removed I guess. We moved to the midwest when i was a toddler. My brother remembers "outten the light" but that is the extent of our repetoire.