I found these in my friends garden, anybody know what they are?

Very interesting Pia. It will most likely turn into some kind of moth or butterfly.
You could put them in a large glass jar and watch them morph into whatever they will become. Just keep adding new food, preferably what they are eating now.
That way we will learn if they are friend or foe.

These are sawfly larvae. It depends on how much you are bothered about them eating the leaves whether or not you view them as a pest.

I had Solomons-seal sawfly for the first time this year, I even saw a female on the plant probably thinking about laying eggs! What did I do? I took a photo! Later on I was privileged to get photos of lots of fat larvae stripping my plants.

It won't be easy to say what they are, the plant might give a clue if you know what it is as many sawfly are plant specific.

I'm Glad they are in somebody else's garden and not yours!

Pia do you know what the plant is that they are feeding on?

Looks like a rose to me I'll check when I return to his garden later on and I'll let you know x