Montana

Montana
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Country:	United States

Rangeland portal / Montana

Montana is a vast and ecologically diverse state in the northern United States, featuring everything from the Rocky Mountains and forested wilderness in the west to expansive plains and prairie in the east. Its ecosystems support a wide range of wildlife, and its rivers contribute to important watersheds like the Missouri and Yellowstone. Grasshoppers are a recurring concern in Montana’s rangelands, where outbreaks can damage forage and crops, especially during dry, warm summers.

State ecology

Montana is ecologically rich, spanning rugged mountain ranges, dense coniferous forests, high-elevation meadows, and expansive prairie grasslands. The western part of the state is dominated by the Northern Rockies, home to alpine ecosystems and diverse wildlife. In contrast, eastern Montana features rolling plains and sagebrush steppe, providing critical habitat for grassland birds, pronghorn, and native pollinators. The state's rivers and wetlands support migratory birds and key fish species such as trout. Grasshoppers are a recurring issue in Montana’s eastern rangelands, where outbreaks can reduce forage availability and affect agricultural productivity.

Grasshopper populations are typically high in the summer, particularly in Montana’s eastern prairie regions where they frequently damage both rangeland and cropland. Their numbers tend to spike in years with warm, dry spring weather. These conditions promote faster grasshopper development and reduce the spread of natural fungal diseases that would otherwise help keep their populations in check.

There is a remarkable phenomenon in the Beartooth Wilderness where large numbers of grasshoppers or locusts have been preserved in ice for several hundred to possibly thousands of years. Grasshopper Glacier is retreating due to warming temperatures and many of these insects are melting out and disintegrating. This process has provided researchers with the opportunity to identify at least one extinct locust species, the Rocky Mountain locust (Melanoplus spretus). The insects are thought to have been frozen during swarming events when they were caught in sudden blizzards. Similar occurrences have been documented in other grasshopper-containing glaciers across the Rocky Mountains. A female striped grasshopper (Amphitornus coloradus) was taken from Grasshopper Glacier at 9,680 feet.

Species gallery

• Highlighted species for Montana
• 
  Obscure grasshopper (Opeia obscura)
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  Packard grasshopper (Melanoplus packardii)
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  Barren land grasshopper (Trimerotropis pistrinaria)
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  Speckled rangeland grasshopper (Arphia conspersa)
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  Broad-banded grasshopper (Trimerotropis latifasciata)
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  Red-legged grasshopper (Melanoplus femurrubrum)
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  Mormon cricket (Anabrus simplex)
• 
  Kiowa grasshopper (Trachyrhachys kiowa)
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  White-whiskered grasshopper (Ageneotettix deorum)
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  Plains lubber grasshopper (Brachystola magna)
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  White cross grasshopper (Aulocara femoratum)
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  Yellowish spur-throat grasshopper (Melanoplus flavidus)
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  Fontana grasshopper (Trimerotropis fontana)
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  Two-striped mermiria grasshopper (Mermiria bivittata)
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  Yuba Lake Jerusalem cricket (Ammopelmatus yubalake)
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  Spring field cricket (Gryllus veletis)

Species of management concern

Grasshoppers have long been an economic concern in Montana. While the state is home to around 70 grasshopper species, only about thirteen are considered economically significant pests. Notable species include the migratory grasshopper (Melanoplus sanguinipes), the clear-winged grasshopper (Camnula pellucida), the two-striped grasshoppers (Melanoplus bivittatus), and the white-whiskered grasshopper (Ageneotettix deorum). These species are commonly found in habitats like stubble fields, roadside ditches, and overgrown pastures, where dry, exposed soil is interspersed with grasses and forbs. Such environments offer ideal conditions for grasshoppers to regulate their body temperature and lay eggs.

Most species overwinter as eggs buried in the top inch of soil. However, some, such as the Speckled rangeland grasshopper (Arphia conspersa), survive the winter as adults but are not considered harmful to agriculture. Grasshoppers begin emerging as nymphs from May through early July, making this a key time for scouting. Since Montana’s pest species overwinter as eggs, the appearance of winged grasshoppers in spring generally indicates non-pest species.

View U.S. Grasshopper Forecast Hazard Maps

Grasshopper management

In 1949, Montana saw its first large-scale grasshopper control efforts using airplanes and newly developed insecticides on rangelands. However, the effectiveness of these operations varied, and the high costs and logistical challenges quickly revealed a gap between the technology’s potential and its practical application. It became clear that a deeper understanding of the biology and behavior of the numerous grasshopper species was necessary. In response, a long-term research program focused on rangeland grasshoppers was initiated that same spring.

Today, the USDA Animal and Plant Health Inspection Service (APHIS) collaborates with landowners to implement control measures, including the application of chemical treatments on rangelands. These efforts are coordinated when outbreaks reach significant levels and are subject to available funding.

Montana State University Extension and the USDA Agricultural Research Service have also hosted workshops to educate producers on grasshopper biology, outbreak predictions, and management strategies.

Grasshopper control can be achieved through biological, chemical, cultural, and mechanical methods, each effective at different times of the year. Biological options include natural enemies like fungi (Nosema locustae), which can be applied in gardens using Nolo Bait. Chemical controls such as Dimilin, Asana XL, and Warrior II are commonly used, with Dimilin being effective early in the season and less harmful to beneficial insects. Cultural practices like early planting, crop and grazing rotations help reduce habitat suitability. Mechanical methods, such as spring or fall tillage, can destroy overwintering eggs, though tillage may reduce soil moisture and lacks a defined cost-benefit threshold.

Featured resource

• 
  Montana.gov grasshopper field guides

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Outbreaks

​Montana has experienced significant grasshopper outbreaks historically and in recent years, particularly affecting rangelands and agricultural areas. These outbreaks have been exacerbated by environmental conditions such as drought and favorable breeding habitats.

According to the twenty-sixth report of the State Entomologist, significant damage to grasslands occurred during the late 1870s and early 1880s, reappeared between 1900 and 1904, and was noted again—though to a lesser extent—in the early 1920s. Additional severe outbreaks were reported from 1934 to 1938 and again from 1947 to 1950. Beyond these major events, varying degrees of grasshopper-related damage have been observed in different parts of the state on an almost yearly basis.

In 2021, eastern Montana and western North Dakota faced the second-largest grasshopper outbreak in the past 35 years. Surveys conducted by APHIS indicated that over 20 million acres in the western U.S. were predicted to exceed the economic threshold for grasshopper infestations, with Montana being one of the most affected states.

The 2022 Hazard Map for Montana predicted higher-than-normal grasshopper numbers, particularly in areas with habitats such as stubble fields, ditches, and weedy pastures.

In 2023, the USDA's grasshopper survey pointed to another challenging year for Montana, with continued infestations expected.

Organizations

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Resources

Name	Year published	Resource link	Descriptive keyword	Language	Author
APHIS regulatory documents	2018		Early warning, Ecology, Public health, Social science, Culture, insecticide, Infestations, Environmental assessment, Rangeland management, Pesticides, Bundle, Environmental impact	English	Animal and Plant Health Inspection Service
ARS grasshopper species fact sheets	1994		Management, Species identification, Series	English	Agricultural Research Services, United States Department of Agriculture
CARMA		View	Prototype cropland, Advice, Rangeland management, Crop health, Grasshoppers, Infestations, Outbreaks	English	Scott Shell Extension Entomology, University of Wyoming
Common Grasshoppers of Montana Cropland and Rangeland		View	Species identification, Management, Biology, Life cycle, Integrated pest management	English	Montana State University
Court rejects federal pesticide-spraying program on millions of acres of western rangelands	2025		Ecology, Spraying, Chemical control, Infestations, Management, Governance, Conservation, Land use management, Habitat	English
Field Guide to Common Western Grasshoppers	2002		Species identification, Field guide	English	United States Department of Agriculture, Robert E. Pfadt
Grasshopper infestation continues after pesticide spray canceled	2023		Spraying, Ecology, Environmental science, Infestations, Emergency response, Chemical control, Grazing	English	Alaina Mencinger
Grasshopper Integrated Pest Management User Handbook	2000		Biological control, Chemical control, Monitoring, Modeling, Population dynamics, Rangeland management, Decision making, Bundle, Ecology, Pesticides, Biopesticide, Integrated pest management	English	Agricultural Research Services, United States Department of Agriculture
Grasshopper investigations on Montana rangelands	1952	View	case study, Species identification, Behavior, Ecology	English	Montana State University, Norman L. Anderson, John C. Wright
Grasshopper watch	2022		Grasshoppers	English
Grasshoppers Are Descending on the West in Swarms	2021		Grasshoppers	English
Grasshoppers of the Western United States		View	Management, Species identification, Key	English	United States Department of Agriculture
Grasshoppers their habits and damage	1964	View	Grasshoppers, Outbreaks, Natural enemies, Ecology, Habitat, Quality illustrations, Species identification	English	United States Department of Agriculture
Grasshoppers, grasshoppers, they're everywhere		View	Grasshoppers, Infestations, Biology, Ecology, insecticide	English	Montana State University, Ruth O'Neill, Kevin Wanner
Hopper helper		View	Survey, Life cycle, Species identification, Integrated pest management	English	Wendal Cushing
Las Vegas resident shares experience as swarms of grasshoppers return to valley	2024		Outbreaks	English
Mega Disasters: Super Swarms of Locusts	2021		General locust education, Video	English
Montana.gov Orthoptera Field Guides		View	Species identification, Management, Biology, Distribution, Map, Rangeland management, Information hub, Website	English
Mormon cricket 'sludge' blankets northern Nevada roads causing crashes	2024		Media article, Outbreaks	English
Overview of the APHIS Rangeland Grasshopper and Mormon Cricket Suppression Program	2022		Management, Chemical control, Grasshoppers, Governance, Video	English	APHIS PPQ Science & Technology Insect Management and Molecular Diagnostics Laboratory (Phoenix Station), United States Department of Agriculture
Overview of the APHIS Rangeland Grasshopper and Moron Cricket Suppression Program	2022		Video, Grasshoppers, Management, Educational video	English	United States Department of Agriculture, APHIS Plant Protection and Quarantine
Pest Grasshoppers of the West	2005	View	Management, Species identification	English	University of Wyoming
Protecting U.S. rangeland from grasshoppers and Mormon crickets	2021	View	Outbreaks, Infestations, Mormon crickets, Rangeland management, insecticide	English	United States Department of Agriculture
Rangeland Grasshopper and Mormon Cricket suppression program	2019	View	Public health, Governance, Culture, Grasshoppers, Economics, Environmental assessment, Life cycle, Biology	English	United States Department of Agriculture
Rangeland Grasshopper Management	1993		Management, Species identification, Control	English	University of Wyoming, Jeffrey Lockwood, Scott Schell
The Grasshoppers of the Western U.S. Lucid mobile app	2016		Management, Species identification	English	APHIS PPQ Science & Technology Insect Management and Molecular Diagnostics Laboratory (Phoenix Station), United States Department of Agriculture, Center for Plant Health Science and Technology of the USDA
The vegetation of rangeland sites associated with some grasshopper studies in Montana	1973	View	Map, Agriculture, Ecology, Grazing, Behavior, Habitat, Data analysis, Geographical differences, Nutritional ecology	English	Montana State University, Norman L. Anderson
USDA APHIS grasshopper forecasting and survey map collection	1930s		Control, Management, Rangeland management, Map, APHIS archive 2024, Grasshoppers, Outbreaks, Forecasting, Historical document, Survey, Uncurated archive, Collection, Historical maps	English	APHIS Plant Protection and Quarantine, United States Department of Agriculture
USDA APHIS historical meeting report collection			APHIS archive 2024, Historical document, Annual report, Uncurated archive, Collection	English	United States Department of Agriculture, Animal and Plant Health Inspection Service
USDA APHIS-PPQ-Science & Technology Phoenix Lab Rangeland Unit project summary	2021		Summary, Set, Project, Project report	English, Spanish, French	APHIS PPQ Science & Technology Insect Management and Molecular Diagnostics Laboratory (Phoenix Station), Animal and Plant Health Inspection Service, United States Department of Agriculture

Rangeland portal / Montana