Looks like scale to me. Are there any ants on the plant? They work together, not in a good way. You can spray with an agricultural oil to smother them.

Yes, scale.

Gently scrape them off with your fingernail. Horticultural oil is only effective at certain stages of the life cycle of the insect. Once it becomes an adult - as these are - the protective 'shell' that covers them prevents the hort oil from being effective.

Yes, we have ants. I cannot seem to get "a handle" on them either.

I wiped the back of a leaf with alcohol and they all came off. It's a huge bush, 5' tall. I'd probably spend a lot of time wiping the leaves. I may do a combination of cleaning leaves until I'm tired of it and then cut off other affected branches.

Thank you all.

Try Tanglefoot on the trunk of the tree. It will prevent the ants from climbing up. Follow the instructions - it's very sticky and you don't want to be stuck to the tree.

Interesting. I could use in the crepe myrtle which is inhabited by the velvety tree ant. Thanks

Or..BOOOO! a systemic poison. It will end the scale problem fast. But- if the tree blooms within a few short months,those flowers will be poisonous to bee's or hummers.

But,as a last case..

I'd rather chop down the schefflera, but thanks for the suggestion. Never heard of Boo. I don't know if the crepe myrtle has scale or not.

No,boooo! was the crowd booing at hearing pesticide use. I acknowledge some have strong feelings about that.

Oh, I thought Boo was a product!! Agree with you on the pesticides. Rarely use but do spray ants when they invade my personal space. I don't care about the standard little black ants, but the velvety tree ants bite and are nasty. Can't be combatted but can be held at bay.