Is this bug damaging?

[alisonb]

I've found several shield shaped bugs on a small periwinkle plant in the garden. They are about 1cm long, black with lots of small cream spots. Some of the leaves have holes in them but they look quite old. I don't mind them, they're quite pretty, but does anyone know what they are likely to be, and whether they are damaging to plants?

[Enrique]

Hi Alisonb,
If they don't scurry around when you poke them, then probably plant feeders.....

[alisonb]

Cheers! I haven't killed any, but have tried to dislodge them by flicking them off. They're quite tenacious.