The potential for grasshopper damage increases as summer progresses. Adult grasshoppers are more likely to move into yards and gardens to find new food sources in July and August when adjacent agricultural crops or grasslands mature or are harvested.
Grasshoppers often damage yard and garden plants by defoliation. Grasshoppers show a preference for flowers and some garden vegetables, such as lettuce, beans and sweet corn. However, when populations are high they will feed on nearly all garden vegetables, as well as trees and shrubs. Small trees and shrubs are the most seriously affected, as defoliation of larger trees will have little impact unless it continues for more than oneyear.
Grasshopper management can be effective if the area to be protected is relatively small and isolated. Protecting a garden from grasshoppers moving out of a large area of adjacent grassland or cropland may be impossible.
Chemical control often is the most effective practice to eliminate heavy infestations of grasshoppers. The best time to control grasshoppers is when they are one-half to three-fourths of an inch long. At this stage, grasshoppers are concentrated in their hatching areas, and can be controlled more effectively than when dispersed later in the summer.
Weedy, untilled areas, such as vacant lots, ditches and poor pastures with mixed grass and broadleaf plants serve as the preferred egg laying and early season feeding areas for grasshoppers. Dense grass growth or regular tillage of these areas will reduce grasshopper numbers. If grasshoppers have removed much of the foliage in these areas, when possible, control them before they can move to lawns or garden plots.
In areas where grasshopper populations are expected to be extreme, consider not planting a garden for a year or plant early maturing vegetables or varieties that are less attractive to grasshoppers, such as tomatoes or squash.
Leaving border areas around gardens and yards unmown also will delay grasshopper movement. Attractive plants, such as zinnias, also can be planted around the edge of the garden to attract and hold grasshoppers. These areas can be sprayed to reduce populations.
Row covers and screens also can help protect more valuable plants. Grasshoppers can eat through most fabric screens, causing damage to storm door and window screening. These screens should be replaced with aluminum screening.
SOURCES: Gary Hein, Ph.D., and John Campbell, Ph.D., UNL Extension Entomologists; and Ron Seymour, Ph.D., UNL Extension Educator
