Grasshopper Numbers Rapidly Increasing in Many Areas of Missouri

Published: June 29, 2012

Numerous grasshoppers can be found in pastures, field borders, and in crop fields in most areas of Missouri. As drought conditions cause the drying of grasses in pastures and field borders, small and medium sized hoppers are moving to field crops to feed. Dry conditions occurring across most of Missouri favor grasshopper survival by reducing the threat from various viral pathogens that reduce grasshopper numbers in most years. The economic thresholds for grasshoppers vary depending on the commodity or non-cropland area requiring insecticide applications for effective grasshopper management. In Missouri, there are approximately 100 species of grasshoppers commonly found, although only 5-7 species are common in field crops. Most entomologist believe that smaller grasshoppers (small nymphs) are more easily controlled with insecticides than larger nymphs or adult hoppers. As with most insects, the larger the hoppers grow, the more foliage and other plant materials they consume. Damage from both nymph and adult grasshoppers is often seen as very ragged feeding wounds located on leaf edges. In severe situations, high numbers of grasshoppers can consume large amounts of vegetation and cause substantial loss of grain and forage yields. Economic threshold information and labeled insecticides are listed with each of the following commodity tables.