What is eating my rose?

At first I thought it was eaf earing bees, but now I find the leaves are being eaten all but completely. I am also finding large amounts of what seems like a black grit underneath. At first I thought it was some form of larvae, but just seemed sand like!

It flowered well its its first flush, but all my next round of buds are failing and falling off :(

Any ideas?

 

Sawfly I think. Any sign of tiny caterpillars ?

Large rose sawfly / RHS

 

Superb diagnosis! That's exactly it! Guess thr black grit is droppings. I popped my glasses on and there the caterpillars were! Pretty well camouflaged too!
Thank you!