Thanks for the link, Tim.
The problem is quite serious as I've now found it in my garden and there is a serious infestation in one particular spot which I think is too far gone for the natural predators.
I think that I will try cutting the garden plants right back to ground level and hope that the rain showers get rid of some of them.
Then, next year, before the hibernating ones get going again, I'll get some of those you recommend ad see if it does the trick.
Thanks, again