Oregon
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| Country: | United States |
Oregon is a state in the Pacific Northwest region of the United States. Its varied landscapes, especially its eastern rangelands, provide important habitat for many grasshopper species. Grasshopper populations here can fluctuate widely, with occasional outbreaks that impact forage and agriculture.
State ecology
Oregon's diverse landscapes—from arid sagebrush steppe in the east to rain-drenched evergreen forests in the west—support a wide range of grasshopper species, particularly in its rangelands and mixed-grass prairies.[1] Eastern and central Oregon, characterized by dry summers and open grasslands, provide ideal habitats for many pest-prone species such as migratory grasshopper (Melanoplus sanguinipes) and clear-winged grasshopper (Camnula pellucida). These regions experience periodic grasshopper outbreaks that can threaten forage availability for livestock and native herbivores.
Grasshopper populations in Oregon are influenced by seasonal climate patterns, vegetation dynamics, and land use. Native grasses like bluebunch wheatgrass and Idaho fescue serve as key food sources, while land management practices such as grazing intensity, prescribed burning, and drought conditions can impact species composition and outbreak potential.
Outbreaks often follow droughts because warm, dry springs boost egg hatching and nymph survival while reducing natural predators and disease. These conditions speed up development and allow populations to surge. Outbreaks reduce forage and plant cover, harming livestock and wildlife, and can lead to erosion. When vegetation is scarce, grasshoppers may invade crops, causing further damage.[2]
Species gallery
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Species of management concern
Oregon's rangelands are home to several grasshopper species considered significant agricultural pests due to their potential to cause substantial damage to forage and crops during outbreak years. Notable pest species include the white-whiskered grasshopper (Ageneotettix deorum), the big-headed grasshopper (Aulocara elliotti), and C. pellucida, which thrive in open grassland habitats. Several species in the Melanoplus genus are particularly problematic, including the two-striped grasshopper (M. bivittatus), the red-legged grasshopper (Melanoplus femurrubrum), the striped sand grasshopper (Melanoplus foedus), the packard grasshopper (Melanoplus packardii), and M. sanguinipes—the latter often being the most destructive due to its high mobility and broad diet. Additionally, the valley grasshopper (Oedaleonotus enigma) may contribute to localized damage.[3]
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Grasshopper management
The Oregon Department of Agriculture (ODA) and USDA's Animal and Plant Health Inspection Service (APHIS) monitor rangeland grasshopper populations, especially during outbreak years. The USDA can treat infested lands when grasshopper populations reach damaging levels, with ODA assisting on federal lands in Oregon. Both agencies support private landowners by providing population updates and treatment guidance. Early identification of pest species is key, as control is most effective during the first three instars using approved growth regulators.
The ODA monitors grasshopper populations across 18 eastern counties to anticipate potential outbreaks. Nymph surveys are conducted at randomly selected sites in May and June to detect early signs of population growth. Adult surveys begin in early July and continue through August, using both random and fixed (sentinel) sites. The 237 sentinel sites provide long-term data on grasshopper densities and species composition, helping track trends and forecast future outbreaks.[3]
Estimating grasshopper densities helps determine if treatment costs are justified. In Oregon, treatment is typically cost-effective at 14 grasshoppers per square yard, where a 10-acre field may host over 600,000 grasshoppers consuming a quarter ton of alfalfa daily. At 8 grasshoppers per square yard on rangeland, the damage can equal the forage needs of a cow for an entire season.[3]
Integrated pest management (IPM) strategies are employed, including habitat monitoring, biological control, and, when necessary, targeted application of reduced agent-area treatments (RAATs) to minimize pesticide use while controlling outbreaks.
Featured resources
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Outbreaks
Oregon is home to 101 documented grasshopper species, but only a few have reached outbreak levels and caused significant damage to rangelands or crops over the past 50 years. Grasshopper outbreaks have fluctuated over the decades, with different species dominating at different times. In the 1980s, widespread outbreaks were primarily driven by five spur-throated grasshoppers in the Melanoplus genus—M. sanguinipes, M. femurrubrum, M. bivittatus, M. packardii, and M. foedus—a group that includes over 30 species in the state. The 1990s and early 2000s saw more localized outbreaks, mostly involving C. pellucida. From 2020 to 2022, outbreaks again intensified and became more widespread, involving C. pellucida, the A. elliotti, the O. enigma, and various Melanoplus species. Notably, in the summer of 2021, Oregon faced its worst outbreak in 50 years, with over 10 million acres of rangeland across 18 counties impacted by economically damaging infestations.[3][4]
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 | |
| 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 and Mormon Cricket Outbreak Media | 2022 | Photos, Outbreaks, Grasshoppers, Mormon crickets | English | Oregon Department of Agriculture | |
| Grasshopper and Mormon Cricket Outbreaks in Oregon Frequently Asked Questions | 2022 | Outbreaks, Grasshoppers, Population dynamics, Management, Set | English | Oregon Department of Agriculture | |
| 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 watch | 2022 | Grasshoppers | English | ||
| Grasshoppers and Mormon cricket, control and suppression of rangeland pests | 2024 | View | Survey, Agriculture, Growth, Monitoring | English | Oregon Department of Agriculture |
| 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 wreak havoc | 2023 | Ecology, Agriculture, Outbreaks, Economics, Crop health, Emergency response | English | Christine Souza | |
| Hopper helper | View | Survey, Life cycle, Species identification, Integrated pest management | English | Wendal Cushing | |
| Klamath Basin braces for a potential grasshopper outbreak | 2026 | View | Media article, Grasshoppers, Outbreaks, Rangeland management | English | |
| 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 | ||
| Oregon grasshopper and Mormon cricket survey summaries | Map, county map distribution, Distribution, Infestations, Survey, Monitoring, Mormon crickets, Economics, Data analysis, Series | English | Oregon Department of Agriculture | ||
| 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 in Oregon | 2024 | View | Species identification | English | Oregon Department of Agriculture, Thomas Valente, J. Buck Dunlap |
| Pest Grasshoppers of the West | 2005 | View | Management, Species identification | English | University of Wyoming |
| Protect your pastures from Mormon grasshoppers and crickets | View | Pesticide management | Spanish | ||
| 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 | |
| UC Integrated Pest Management for Home Gardeners and Landscape Professionals | 2013 | View | Life cycle, Pesticide management, Management | English | University of California Statewide Integrated Pest Management Program |
| 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 | |
| Watch out for grasshoppers! | 2016 | View | Weather, Management, Culture, Chemical control, Biological control, Photos, Life cycle | English | Amy J. Dreves, Nicole Anderson, Clare Sullivan |
References
- ↑ U.S. Geological Survey (USGS) (2025) Ecoregions of Oregon. U.S. Department of the Interior. https://dmap-prod-oms-edc.s3.us-east-1.amazonaws.com/ORD/Ecoregions/or/or_front.pdf
- ↑ Oregon Department of Agriculture (2024) Grasshoppers and crickets survey and treatment. Oregon Department of Agriculture. https://www.oregon.gov/oda/ippm/survey-treatment/Pages/grasshoppers-crickets.aspx
- ↑ 3.0 3.1 3.2 3.3 Valente T (2024) Pest grasshoppers in Oregon: A field guide to nymphs and adults. Oregon Department of Agriculture. Text and keys by Valente T; images by Dunlap JB, Valley S, Shahan T, Valente T; layout by Dunlap JB. https://hopperwiki.org/images/b/ba/Pest_grasshoppers_in_Oregon.pdf
- ↑ Oregon Department of Agriculture (2024) Grasshopper and Mormon Cricket outbreaks in Oregon: Frequently asked questions. Insect Pest Prevention & Management Program, Oregon Department of Agriculture, 635 Capitol St NE, Salem, OR 97301-2532. https://www.oregon.gov/oda/ippm/survey-treatment/Pages/grasshoppers-crickets.aspx