Grasshopper Nymphs Present in Missouri

Published: July 27, 2009

Grasshopper nymphs can be found throughout Missouri. Typically a summer pest on field crops, the wet conditions in most areas of the state have allowed for the buildup of this pest in the lush, green vegetation of field borders, waterways, and in no-till fields. At present grasshopper nymphs range from very small in size up to 1/2 –inch in length. Wet years usually do not favor grasshopper populations as fungal pathogens can cause high mortality of small grasshoppers. This year the wet weather has not helped with grasshopper mortality, possibly allowing for grasshopper populations to build to problem levels. In Missouri, over 100 grasshopper species can be found although 6-7 species may cause problems in field crops. Typical grasshopper damage consists of irregular shaped holes extending from the leaf margin to the center of the leaf. Damaged tissue surrounding the feeding wound often has dead tissue surrounding the wound. Grasshoppers are capable of doing considerable damage in a very short time, especially at they grow in size. Adult grasshoppers (winged) are more difficult to control than smaller nymphs (wingless).

The following table lists the economic threshold for grasshopper infestations in non-cropland areas and grass pastures, corn, soybean, grain sorghum (milo) pesticide label directions and precautions.