If you own acreage in Northwest Montana, you’ve likely seen grasshoppers. In normal years, they’re a management nuisance. But during outbreak years (which happen frequently across the western United States), grasshoppers can devastate pastures, gardens, trees, and ornamental landscaping in a matter of days.
Understanding how grasshoppers behave and why rapid control is critical can help you protect your property investment before damage occurs.
The Scale of the Problem
Grasshoppers are among the most destructive herbivores in grassland ecosystems. A single grasshopper eats its body weight in vegetation daily and wastes six times more plant matter in the process. When populations explode across millions of acres simultaneously, the economic impact is staggering: annual losses to U.S. rangelands average around 25%, exceeding damage from from all other rangeland insects combined.
While large-scale agricultural losses grab headlines, rural homeowners face serious threats, too. During heavy infestations, grasshoppers attack virtually any plant, including high-value investments like mature trees, ornamental shrubs, flowers, and turfgrass. For property owners who’ve invested significantly in landscaping or are establishing orchards and gardens, an outbreak can wipe out years of work.
Why Grasshoppers Are So Hard to Control
The primary challenge with grasshoppers is their mobility. Once they mature and develop wings (typically by mid to late summer), they can fly miles in search of food. This means individual property owners treating only their own land often see only temporary relief as new waves of grasshoppers continually migrate in from surrounding areas.
For effective control, area-wide management is generally required. Coordination with neighbors or professional applicators treating larger swatch of land yields far better results than isolated efforts.
The Critical Window: Timing is Everything
The best opportunity to control grasshoppers occurs from mid-May through early July, when they’re still wingless nymphs. During this stage, they remain relatively concentrated near their hatching areas: often fence rows, roadsides, and field edges where vegetation first emerges.
Nymphs are vulnerable and less mobile, making treatment far more effective and less expensive. Once they develop wings and begin dispersing, control becomes a “hit-and-run” scenario that’s both difficult and costly. By that point, you’re chasing a moving target that can simply fly away from treated areas and return days later.
Treatment Options: What Works and What Doesn’t
Chemical Control
For property owners facing immediate threats to valuable landscaping or pastures, chemical insecticides remain the most effective option. Modern approaches emphasize responsible use:
Reduced Agent and Area Treatments (RAATs)
This strategy involves applying reduced rates of insecticide in alternating treated and untreated strips rather than blanket coverage. As grasshoppers move from untreated refuge areas into treated zones, they consume treated vegetation and are killed. RAATs reduce insecticide used by 65-70% compared to conventional broadcast applications while maintaining comparable efficacy.
Targeted Bait Applications
For smaller areas like pastures, fence rows, or around residential properties, carbaryl bait (bran mixed with insecticide) offers a more targeted approach than spraying. This method concentrates control where grasshoppers are feeding while minimizing broader environmental impact.
Insect Growth Regulators (IGRs)
Products like diflubenzuron interfere with the grasshopper molting process rather than acting as neurotoxins. These are extremely non-toxic to mammals, birds, and fish (birds can even eat affected grasshoppers without harm). IGRs are the product of choice in many federal and private grasshopper control programs.
When applied by licensed professionals during the nymph stage chemical treatments can produce rapid control (often within the first two days), preventing major damage to crops and landscaping.
Biological Control: Limited Applications
Biological control agents like Paranosema locustae offer an environmentally safter alternative with minimal effects on human health and non-target species. However, their characteristics that make the safer also limit effectiveness when rapid protection is needed.
The Timing Problem
Biological agents are slow-acting. Grasshoppers infected with P. locustae don’t show disease symptoms for several weeks, with peak mortality occurring 40-60 days after application. By that time, significant damage to your property may have already occurred.
Efficacy Limitations
While biological controls work well for homeowners managing small garden populations, field data shows they often fail against large-scale outbreaks from both efficacy and economic standpoints.
Environmental Constraints
Some biological agents, like entomopathogenic fungi, require high humidity to function effectively (conditions rarely found int he semi-arid climates where grasshopper outbreaks are most common). This environmental mismatch further limits their practical use.
For these reasons, biological controls are better suited for long-term population management in low-density situations rather than protecting property during active infestations.
What Montana Property Owners should Do
- Scout early and often: Beginning in May, walk your property edges, fence lines, and areas where vegetation emerges first. Look for concentrations of wingless nymphs.
- Act during the nymph stage: If you see significant population of young grasshoppers, that’s your window. Waiting until adults are flying dramatically reduces your control options.
- Consider area-wide coordination: Talk to neighbors about their observations and control plans. Coordinated treatment across multiple properties is far more effective than isolated efforts.
- Work with licensed applicators: Professional pest management applicators have access to more effective products, application methods like RAATs, and the expertise to time treatments appropriately. For properties with significant landscaping investments, professional application often proves more cost-effective than repeated DIY attempts.
- Plan for next season: If you experienced an outbreak this year, discuss preventive monitoring and early intervention strategies with a land management professional before next spring.
The Bottom Line
Grasshoppers are a recurring challenge for Montana property owners, but they don’t have to mean devastating losses. The key is understanding their lifecycle, recognizing the critical treatment window, and choosing control methods appropriate to the scale and urgency of the threat you’re facing.
For rural residential properties where years of landscaping investment or productive pastureland are at stake, rapid and effective control during the nymph stage (typically through professionally applied chemical treatments using reduced-impact methods) offers the most reliable protection.
Sources and Further Reading
Dakhel, W.H., Jaronski, S.T., & Schell, S. (2020): Control of Pest Grasshoppers in North America. Insects, 11 (9), 566. A comprehensive review of grasshopper control methods in North America, covering chemical, biological, and integrated management strategies.
Evens, E., & Hodgson, E. (2008): Grasshoppers (Condensed version). Utah State University Exension, Plant Health. Practical extension guide covering grasshopper identification, lifecyle, damage assessment, and control options for western landowners.
Hemken, D. (2024): Word’s Best Practice Locust and Grasshopper Management: Accurate Forecasting and Early Intervention Treatments Using Reduced Chemical Pesticide. Agronomy, 14, 2369. Recent research on optimizing grasshopper management through improved forecasting and reduced-pesticide intervention strategies.
Lockwood, J.A., & Schell, S.P. (1997): Decreasing Economic and Environmental Costs Through Reduced Area and Agent Insecticide Treatments (RAATs) for the Control of Rangeland Grasshoppers: Empirical Results and Their Implications for Pest Management. Journal of Orthoptera Research, 6, 19-32. Foundational research establishing the effectiveness and environmental benefits of RAATs methodology.
Stotts, D. (2008): The Future is Now for Rangeland Grasshopper Scouting. Oklahoma State University, New and Media. Article discussing advances in early detection and monitoring techniques for rangeland grasshopper populations.
Zhang, L., & Lecoq, M. (2021): Nosema locustae (Protozoa, Microsporidia), a biological agent for locust and grasshopper control. Agronomy, 11, 711. Detailed examination of the most widely used biological control agent for grasshoppers, including efficacy data and application guidelines.
These resources provide technical and scientific backing for grasshopper management recommendations. For Montana-specific questions or property assessments, contact Wildgrove Land & Forest Management, LLC.
