Gooseberry pest folds & glues leaf

Hi folks
This is the second year, of two, where I've seen a pest take one of the topmost leaves, it takes a natural fold and increases it and glues the edge making a pocket.

It (it's a fly) either crawls inside and metamorphosises, or it lays eggs. Last night I came across one of these, I pulled it apart and something darted out and flew? away.

Last year whatever was in there was eating the leaves.

The glue is pretty much a web-like material... I think it uses strands to hold the folded leaf together.

Sorry for the sparse detail,can anyone name that bug? ;-)
Thanks

 

Could it be tortrix moth? I get a lot of trouble with those in the greenhouse.

 

Check. Saw-fly larva.

 

An appreciative "thank you".

On the Gooseberry bush I've since found a rolled-up leaf near the top, I dug into it and found a small (about 7mm long), darkish mid-green caterpillar in a web "cocoon".

This fits the Tortix moth descriptions.

All my gooseberry leaves are so bent and curved it would be impossible to lay one flat out, it looks like this insect takes advantage of a natural quirk in that the edges of some leaves are already in a "U" shape and so don't need much effort to form a pocket for reproducing.

P. S. While I am here, what are these light mid-green caterpillers on my potato plants? I don't think the gooseberry & potato caterpillers I've found are the same species? Image of pest on potato leaves is attached. Thanks

 

Must admit, I wasn't certain. A quick check with the RHS and that's what turned up.
Glad you sorted it in the end.

 

I've got something very similar that's making use of the top leaves of my recently-planted willows. Like you, I found a small caterpillar in the one I investigated. I was a bit worried, but the willows don't seem to mind so I'm just going to leave them be.