Grasshoppers

Grasshoppers have large hind legs adapted for jumping, short antennae relative to their body (distinguishing them from crickets and katydids), and chewing mouthparts. Colour and size vary widely among species, from a couple of centimetres to several centimetres long.

Damage appears as ragged, irregular feeding along leaf margins and, at higher densities, complete stripping of foliage and feeding on seed heads and stems.

Most pest grasshopper species overwinter as eggs laid in soil, particularly in undisturbed field margins, rangeland, and roadsides. Nymphs hatch in spring and develop through several instars before becoming winged adults, with warm, dry conditions generally favouring egg survival and faster development.

Feeding reduces photosynthetic leaf area and can damage seed heads directly, with the greatest impact typically occurring when large numbers move from drying field margins or rangeland into adjacent crops as vegetation there declines.

Host crops include wheat, maize, and sorghum, along with many rangeland grasses and other field crops, particularly at field edges.

Counting nymphs and adults in field margins and rangeland during spring, and monitoring conditions known to favour outbreaks, such as warm, dry weather following egg-laying seasons, help anticipate movement into crops and inform timely field-edge scouting.

Grasshopper management typically targets field margins and early nymphal stages before large populations move into the crop itself.

• Monitor field margins and rangeland for nymphs early in the season
• Conserve birds, predatory insects, and entomopathogenic natural enemies
• Manage vegetation at field edges to reduce egg-laying and early nymphal habitat where appropriate
• Coordinate monitoring and any response at a landscape scale, since populations move between rangeland and cropland