Cucullia verbasci (Mullein Moth) caterpillar

Normally I love having wildlife in the garden and I'm loving all the different types of bees who are visiting. I'm less sure about these critters though... Both buddleia bushes have 4 inhabitants that I can see i.e. 8 caterpillars in total and there's already a fair amount of chomping that's been going on :( does anyone know the risk to the plants? They're about 3ft tall at the moment :/

Hope you've had a good day.

Extra photo of one of the Hostas that's coming into flower.