As herbivores, grasshoppers eat the plants in their surroundings; many of them enjoy feasting on farm crops. Before the era of corporate farming in the United States, grasshoppers were a big concern for family farmers. In the developing world, grasshoppers still devastate crops from time to time.
According to the U.S. Department of Agriculture, five species of grasshopper are particularly destructive to cropland: two-striped, differential, red-legged, Packard and migratory grasshoppers.
If you are concerned about grasshoppers ruining your landscaping, put down insect bait with carbaryl in it. The ideal time is late May or June, when most grasshoppers hatch. Don't put the bait out right before a rainstorm or you will have to put more out. Choose an insecticide with acephate, permethrin or diflubenzuron. Mix in some canola oil before spraying; the oil lures grasshoppers to the treated plants. These measures are less effective in grasslands or pastures.
One very simple "organic" method is to install a birdhouse in your backyard, as birds feed on the long-legged insects. If you prefer to use an organic spray, look for products containing Nosema locustae or Beauvaria bassiana; these are diseases to which grasshoppers are susceptible, but which will not harm other creatures in the area. Nosema is available in combination with a wheat flake. Neem oil is an organic repellent.