When they're very small you can use the Nolo bait. When they're big it's better to spray the garden with SurroundWP. I did that last year when they got bad, but then we had a couple of unusually wet weeks when the Surround mostly washed off and the grasshoppers had their way with my garden.
Trouble with grasshoppers is that they travel, so even if you kill them with Nolo, your neighbor's grasshoppers will visit you. Someone who eventually invents a trap for these things will end up rich beyond his or her wildest dreams.