The NDSU Extension IPM crop scouts surveyed over 790 fields of wheat, barley, soybean and sunflowers in North Dakota recently. Grasshoppers were observed in 70% of the fields surveyed, says Janet Knodel, NDSU Extension entomologist.
Grasshopper populations are increasing in some areas and densities ranged from 0 to 63 adults per square yard. Hot spots were in Williams and Emmons Counties (see map).
Continue to scout field margins and fields for economic infestations of grasshoppers, which are 21-40 adult per square yard in field edges or 8-15 adults per square yard in fields, Knodel advises.
If counting the number of grasshoppers per square yard is too difficult due to large numbers of grasshoppers, count the number per square foot and then multiple that number by nine for the number per square yard.
Dry and hot conditions will favor grasshopper development into the late summer, Knodel says.Source: NDSU Extension