Berberis decimated - help please!

[Loopzy]

I've just noticed this shrub was looking very sparse in the centre, so had a look and it is covered in small caterpillars. I'd say two thirds of the leaves have been eaten. So far, I have tried picking them off by hand, but this proved difficult because of the thorns. I have also sprayed them with the hosepipe, which seemed quite effective, but the ones that didn't die, are now heading back to the leaves.

Does anyone have any advice? I would rather not use anything which could harm bees.

Thanks

Berberis sawfly this is RHS advice. My Berberis has suffered from this pest in the past, but seems to have escaped trouble for the last few years.

Scroll down for how to treat, the plant will recover next year, but it may get attacked again.

Thank you. It's good to know the plant will recover next year. I'll keep picking them off by hand for now and keep an eye out next year. I need to check they haven't spread to the others now.