Green trapeze

This caterpillar and its fellows have almost stripped the leaves from my Georgian madder plant,  expelling the residue as many tiny pellets, which were what first caught my attention, so well camouflaged are the larvae  themselves.

 I think it's a bright-line brown-eye (Lacanobia oleracea)  caterpillar, a common species. I will leave them in situ and trust the plant survives. Mostly they do because why kill your future generation's food source?

https://www.bbc.co.uk/future/article/20240503-why-you-should-let-insects-eat-your-plants