Thank you for reaching out to ask2.extension.

I’m not sure you have scale.  Scale would be a rough covering over the bark.  Check to see if you have small individual insects.  My identifier as well as the ants suggest black  aphids.  

if just the tops of the branches are affected, cut them off and dispose of them in the trash.  If the infestation is more wide soread, you may want to treat the shrubs.  

Go to extension.umn.edu and search for aphids in home gardens and yards.  The article will give you different ways to get rid of them, including pesticides that I can’t suggest.

I’d check other plants and shrubs that are near this one.  Aphids can affect many plants.

Good luck.