Many insect predators need an alternate food source, such as tiny flowers rich in nectar. As an example, I find that annual rudbeckias with green centers are a favorite food source of the adult soldier beetle whose larvae feed on grasshopper eggs. These predators are very common in a garden with many daisy type flowers. Maybe the grasshopper population will come into balance with no action on my part, other than growing more rudbeckias. I certainly hope so.
Major damage is done to seedlings.
Baby grasshoppers cut them short in early spring and then seem to move on to other plants. In late summer, grasshoppers are back chewing on a few flowers. They have also eaten holes into seed pods. Of course, I set too many pods anyway and can afford to lose a few. The less toxic chemical sprays such as Malathion are quite effective.