Best Practices for Controlling Red-Shanked Grasshoppers

Red-shanked grasshoppers (Melanoplus femurrubrum) are a common pest known for their voracious appetite and ability to cause significant damage to crops, gardens, and natural vegetation. These insects are particularly destructive in agricultural areas where their feeding can lead to reduced yields and economic loss. Effective control of red-shanked grasshoppers requires an integrated approach combining cultural, biological, mechanical, and chemical methods.

In this article, we will explore best practices for controlling red-shanked grasshoppers, focusing on sustainable and efficient strategies to minimize their impact.

Understanding Red-Shanked Grasshoppers

Before diving into control methods, it is essential to understand the biology and behavior of red-shanked grasshoppers:

• Identification: They are medium-sized grasshoppers characterized by bright red hind legs (the “red shanks”), yellowish to greenish bodies with variable markings.
• Life Cycle: Eggs are laid in soil during late summer and hatch in spring. Nymphs go through multiple instars before becoming adults by mid-summer.
• Feeding Habits: They feed on a wide variety of plants, especially grasses and crops like alfalfa, wheat, corn, and vegetables.
• Population Dynamics: Their populations can explode rapidly under favorable weather conditions, especially warm and dry periods.

Understanding these factors helps tailor control strategies effectively.

Cultural Control Methods

Cultural controls involve modifying the environment or agricultural practices to reduce grasshopper survival and reproduction.

Crop Rotation

Rotating crops disrupts the habitat preferred by grasshoppers. Since red-shanked grasshoppers favor certain grasses and legumes, alternating with crops they find less palatable can reduce their food supply and discourage population build-up.

Early Planting

Early planting can help crops establish before peak grasshopper hatching occurs, allowing plants to outgrow or better withstand initial feeding damage. This timing also helps disrupt the synchronization between grasshopper nymph emergence and vulnerable crop stages.

Habitat Management

• Vegetation Control: Reducing weeds and tall grasses in field margins decreases breeding sites and shelter for nymphs.
• Tillage: Plowing fields in late summer or early fall can expose eggs to predators and harsh weather, lowering hatching success.
• Maintaining Healthy Soil: Vigorous crops are more resilient to feeding damage.

Use of Trap Crops

Planting trap crops that attract grasshoppers away from the main crop can concentrate pests in manageable areas where targeted control can be applied.

Mechanical Control Methods

Mechanical methods physically remove or kill grasshoppers.

Hand Picking

In smaller gardens or low infestation areas, hand picking adult grasshoppers can reduce numbers. While labor-intensive, this method is pesticide-free and environmentally safe.

Barriers and Traps

• Physical Barriers: Installing row covers or insect netting prevents grasshoppers from reaching crops.
• Sticky Traps: Yellow sticky traps attract many insects but have limited effectiveness as a sole control for grasshoppers.
• Vacuum Devices: Some farmers use commercial vacuum devices to suck up large numbers of nymphs in small areas.

Soil Disturbance

Regularly disturbing soil where eggs are laid destroys egg pods or exposes them to predators.

Biological Control Methods

Biological controls employ natural enemies and pathogens to manage pest populations sustainably.

Natural Predators

Several animals feed on red-shanked grasshoppers:

• Birds such as starlings, sparrows, crows
• Small mammals like mice
• Predatory insects including spiders, beetles, wasps
  Encouraging these predators by creating habitats or avoiding broad-spectrum insecticides benefits pest control.

Pathogens

• Entomopathogenic Fungi: Fungal pathogens like Metarhizium anisopliae specifically infect grasshoppers causing disease outbreaks that reduce populations.
• Nosema locustae: A microsporidian parasite used commercially as a biocontrol agent targets grasshopper digestive systems leading to mortality. Applied as bait formulations, it acts slowly but reduces populations over time without harming non-target species.

Biological Pesticides

Products based on Bacillus thuringiensis (Bt) have limited efficacy against mature grasshoppers but may impact young nymphs when properly applied.

Chemical Control Methods

Chemical pesticides provide rapid knockdown but should be used judiciously within an integrated pest management (IPM) approach due to environmental concerns.

Insecticide Options

Several classes of insecticides are effective against red-shanked grasshoppers:

• Organophosphates (e.g., malathion)
• Carbamates
• Pyrethroids
  These chemicals can be applied via ground sprays or aerial applications depending on infestation size.

Application Timing

Targeting early nymph stages is more effective since adults are more mobile and harder to control. Monitoring populations through sweep nets helps determine proper timing.

Safety Precautions

Always follow label instructions carefully to minimize risks to beneficial insects such as pollinators and natural predators. Avoid spraying during bloom periods or windy conditions that cause drift.

Integrated Pest Management (IPM) Approach

The best strategy incorporates multiple control methods tailored to local conditions:

1. Monitoring & Identification
   Regular scouting allows detection of early infestations before they reach damaging levels.
2. Threshold-Based Action
   Taking action only when populations exceed economic thresholds reduces unnecessary pesticide use.
3. Combining Controls
   Using cultural methods first followed by biological controls creates a hostile environment for grasshoppers.
4. Selective Pesticide Use
   When necessary, choose targeted insecticides that minimize environmental harm.
5. Record Keeping & Evaluation
   Documenting pest levels and control outcomes improves future management decisions.

Environmental Considerations

Controlling red-shanked grasshoppers responsibly requires balancing pest suppression with conservation:

• Avoid widespread insecticide use that harms pollinators.
• Preserve natural predator habitats around fields.
• Use biopesticides whenever possible.
• Rotate pesticides with different modes of action to prevent resistance buildup.

Conclusion

Red-shanked grasshoppers pose a significant challenge for farmers, gardeners, and land managers due to their capacity for rapid population growth and crop damage. Employing best practices that integrate cultural adjustments, mechanical removal, biological agents, and judicious chemical treatments offers the most effective control strategy.

Monitoring populations closely and applying interventions at appropriate times ensures healthier crops while minimizing environmental impact. By adopting an integrated pest management approach focused on sustainability, producers can keep red-shanked grasshopper infestations under control year after year.