This is a picture of Graptocoris aulicus, from the Field Guide to Insects of South Africa, by Mike Picker, Charles Griffiths and Alan Weaving - thanks to Lyn McCallum for the reference and I found the entire book online. This looks a lot like the babies on the terrace. Yesterday.
Cue ominous music.
The empty nest.
German girl, in Arlington, said, Harlequin Bugs. I Googled. Troilus luridus (indeed). I went out to see the nursery. And I must say the little buggers are up and moving today and they look very active and harlequin buggy. Which is BAD! They eat plants.
They have jacked-up legs like those crazy trucks driven by men with manhood issues, and long feelers and it seems I have carefully nurtured a plague on my terrace!
And now they are gone, all gone.
Should've stomped them when I had the chance.