Crickets and Grasshoppers Eating Roses?

I moved to my house 2 years ago, I had lovely established roses in the garden and had bought my potted roses from my rental with me, and within a year the crickets/grasshoppers had killed all my potted roses and decimated my established ones. I pruned well this year, weeded well, fed the roses with Black Marvel, and they are ready to flower. They look so lovely, and the crickets are back badly, hundreds of tiny green ones and a couple of massive big greyish brown ones, so far.

Last year I used to pick off everyone of them, whilst watering by hand, and killing them, but to no avail. I obviously have to treat the soil as well as the plant, but they have had their way here for years I'd say. I need to kill them and quickly before they kill off my roses before they even put out a rose! Help.

By Jules from Perth