Grasshopper Management

Abstract

<p>Grasshopper populations are present at some level in Iowa field crops each year. Widespread fluctuations in grasshopper populations occur as a function of natural factors such as weather conditions, predators, parasites and disease. Severe infestations usually occur during periods of hot and dry weather. During the drought of 1988 and 1989, grasshopper populations grew to extremely high numbers. This dramatic increase is made possible by the tremendous reproductive capacity of grasshoppers. During dry years, female grasshopper have been found to lay 400 eggs in one season. Conversely, cool, wet weather coupled with the presence of natural enemies, severely limit reproduction and survival leading to reduced populations. Feeding by large numbers of grasshoppers can cause significant yield loss or crop removal. C.J. Drake and G.C. Decker in 1932 stated that "Seventeen adult differential grasshoppers per square yard in a 40-acre alfalfa field consume a ton of dry alfalfa per day." c. Wakeland in 1946 stated that "A grasshopper will eat its own weight in green food in about 16 hours" (Hantsbarger, 1979).</p>