Waspy thing on olive tree

Showing my ignorance again about insect life... it looks kind of waspy.
I have done a half-hearted search to find out exactly what it is called but I'm so busy I've had to abandon the search.

I blipped whatever it is early this morning knowing that photography would be well down on my list of "to do's" today.

It's one of those needy people days today amongst other things.