Fewer eggs are produced in cooler and wetter weather. Some grasshoppers prefer one food source, such as corn or alfalfa, but when food is scarce they eat a variety of plants, shrubs and trees. A grasshopper will eat its own weight in green food in about 16 hours. In fact, seven grasshoppers per square yard over 10 acres will eat the same ration as one cow. Grasshoppers have several natural enemies including birds, rodents, spiders, skunks, several species of flies and horsehair worms.
Horsehair worms are long and whitish and live inside a grasshopper.
As they feed on their living host, they cause sterility in female grasshoppers. When the worms complete their growth inside the grasshopper, they kill the insect by forcing their way through the body wall. Grasshoppers ingest hair worms when they eat leaves where hair worm females have laid eggs. There are several insecticides that control grasshoppers. Carbaryl, sold as Sevin, and Malathion can be used as a spray.