Help! What has attacked my blackcurrant bush?

[MissBeaHaving]

As you can see from the pictures something is eating the leaves
I can't see any insects but something must be there.

I've also only got half a bowl of berries this year,not sure if whatever is eating the leaves is the reason ?
I'm hoping to prevent this happening next year!

Probably the larvae of the blackcurrant sawfly - have a look underneath the leaves.

Thanks NanTheWiser,I will have a Google.

I can't see any crawlies but I've just found a little white shell/cocoon on the bottom right of one of the leaves.

My blackcurrents have had a very low yield of fruit this year. Shame as I really enjoy homemade blackcurrent jam.

Agree probably sawfly my gooseberry bush had its leaves stripped until only the veins were left.