I’ve just seen this horrible mess on one of my climbing plants ( don’t know the name of it ?) It’s like a black mould. Nothing has been eaten. I might not be back for a while because summer has come today so I’m out there.
I can't really see from the picture, but its probably sooty mould growing on the sticky mess left by scale insect. Difficult to erradicate even with insecticide, so i would suggest you blast it with a hose.