Utah State University Extension
Springtime, while grasshoppers are still nymphs, is the best time for communities or neighborhoods to work together to suppress grasshopper populations. Treating as wide an area as possible is the key to success. When grasshoppers become adults, they can travel great distances and may not remain in one area long enough for an insecticide to be effective.
Murray, Marrion, "Community-wide Grasshopper Control" (2018). All Current Publications. Paper 884.