Pest Control · August 2025 · 5 min read
Grasshopper outbreaks can strip pastures of forage in days during hot, dry summers. Early monitoring and well-timed treatments targeting nymphs before they reach adulthood provide the most effective and economical control.
Begin scouting field margins and roadsides in late spring when grasshopper nymphs first hatch. Walk a transect through the field and count the number of grasshoppers flushed per square yard. Focus on south-facing slopes and areas with bare ground, where eggs are most commonly deposited and nymphs concentrate in early instars.
Treatment is generally warranted when counts exceed 8–10 nymphs per square yard on rangeland or 15–20 per square yard in field margins that threaten adjacent crops. Treating nymphs in the third and fourth instar provides the best control timing — they are large enough to consume bait but have not yet developed wings. Waiting until adults are flying makes control much more difficult and expensive.
The Reduced Agent and Area Treatment (RAAT) approach applies insecticide to alternating swaths, reducing chemical use by 50% while maintaining 85–90% control as grasshoppers move into treated strips. Diflubenzuron bait and carbaryl bait are common options for pastures. For organic operations, Nosema locustae biological bait provides slower but cumulative population reduction over multiple seasons.
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