Small Grasshoppers Numerous in Many Areas of Missouri

Published: July 5, 2010

Several regions of Missouri are experiencing high numbers of small grasshoppers. Historically wet years have not favored grasshopper populations as high moisture levels tend to allow bacterial and fungal pathogens to attack developing grasshopper nymphs. This has changed in the past 5 years as grasshopper populations tend to build whether wet conditions are present or not. 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 although only 5-7 species are common in field crops. Although there is conflicting data, 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 is listed with each of the following commodity tables.