Gooseberry Sawfly larvae.

[Galette]

This is the second year that my gooseberry bushes have been stripped bare by these little blighters, and this year's crop has been poor.  I have tried a daily prowl around the bushes on 'squash patrol', but clearly it wasn't enough to keep the numbers down, I also gave the bushes a tar wash in February.

Any suggestions please?

[Galette]