Grasshoppers are among the most difficult insect pests to manage in the garden. When numbers are low, they can be hand-picked and squashed. Cones, screened boxes, floating row covers, and other protective covers provide some protection if numbers are not high. However, grasshoppers will eat through cloth or plastic row covers if they are hungry enough. Try using metal window screening. Poultry, including chickens and guinea hens, are excellent predators, but can also cause damage to some garden plants.
....Gardeners can apply a bait containing carbaryl around the borders of their garden before grasshoppers arrive. If a grasshopper trap crop is being grown around the border of your garden, these plants can be baited or sprayed with carbaryl or other products to kill grasshoppers. These insecticides have only a few days of residual activity against grasshoppers, and baits lose their effectiveness after rain or irrigation, so they will need to be reapplied if migrations continue. Small grasshopper nymphs are easier to control with insecticides than adults and large nymphs.
Once grasshoppers have invaded the garden, insecticides will not be very effective. Reserve the use of insecticides for serious situations where they may provide a significant level of control. Carbaryl, especially in its spray form, is very toxic to bees, to natural enemies of grasshoppers, and to aquatic life.