When Coloradans talk about grasshoppers, they really are talking about the grasshopper genus, Malanoplus. Several species of grasshoppers can be located in Colorado but ninety percent of the damage is caused grasshoppers in this one genus. Females of one species in this genus can lay up to 400 eggs in a single season.
Weather conditions have something to do with egg-laying. With cooler and wetter weather, fewer eggs are produced. To put egg laying and grasshopper populations in perspective, if a female lays 200 eggs in one season, 198 eggs or young grasshoppers must die before they mature to keep the population the same the following year.
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.
Grasshoppers have several natural enemies including birds, rodents, spiders, skunks, several species of flies and hairworms (nematodes). 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. Carbaryl (Sevin) and Malathion can be used as a spray. 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.
Photo: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010