Some grasshoppers prefer one food source, such as corn or alfalfa, but when food is scarce they will eat a variety of plants, shrubs and even trees. Within 16 hours, a grasshopper will eat its own weight in green food. Seven grasshoppers per square yard over 10 acres will eat the same amount as one cow. Hairworms are long and whitish and cause sterility in females as they feed on body contents. As the worms complete their growth inside the grasshopper, they kill the insect by forcing their way through the body wall.
Grasshoppers ingest hairworms as they feed upon leaves where hairworm females have laid eggs.
Several insecticides are used to control grasshoppers. Sevin also can be used as a bait. A microbial insecticide called Nosema locustae is sold under various trade names for grasshopper control. This is a protozoan disease that occurs naturally among grasshoppers and has been commercialized by mass production under laboratory conditions. For more information on Gardening, contact your local Colorado State University Cooperative Extension office .