Colorado

Colorado
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Rangeland portal / Colorado

Grasshoppers are a common and ecologically significant group of insects in Colorado, with over 100 species found across the state’s diverse landscapes. They thrive in grasslands, rangelands, and agricultural areas, playing a crucial role in the food web. While they contribute to ecosystem health by aiding in nutrient cycling and plant growth regulation, some species can become significant agricultural pests.

State ecology

Colorado's diverse geography, including the Rocky Mountains, plains, and plateaus, shapes its grasshopper populations. Droughts and varying terrain contribute to population fluctuations. Grasshoppers thrive in the semi-arid climate of the plains and foothills. Higher elevations support species adapted to cooler temperatures. Grasshoppers typically lay their eggs in undisturbed areas during late summer and early fall. Most species pass the winter as eggs. The eggs hatch the following spring, and nymphs develop into adults about five to six weeks later. However, a few Colorado species hatch in late summer and overwinter as nymphs, and winged adults emerge early the next summer. This early appearance can sometimes cause unnecessary concern about grasshopper activity. While some of these early-season species impact rangelands, they do not pose a threat to field crops.

In Colorado, species likely to overwinter as nymphs include the speckled rangeland grasshopper (Arphia conspersa), the mormon cricket (Anabrus simplex), Arphia sulphurea, Chortophaga viridifasciata, Cibolacris parviceps, the velvet-striped grasshopper (Eritettix simplex), the coral-winged grasshopper (Pardalophora apiculata), Pediodectes haldemanii, brown-spotted range grasshopper (Psoloessa delicatula), the Texas spotted range grasshopper (Psoloessa texana), Trachyrhachys coronata, the red-shanked grasshopper (Xanthippus corallipes), and the Montana band-winged grasshopper (Xanthippus montanus). Additionally, some high-altitude grasshopper species may also overwinter as nymphs. The red-shanked grasshopper is unique in that it spends its first winter as an egg and a second winter as a nymph. In rare cases, adults may even survive through the winter.

Species of locust and grasshoppers in Colorado represented in the HopperWiki

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Species of management concern

Colorado is home to 133 distinct grasshopper species. However, only about twelve are considered major pests in rangelands, with just five causing the most damage. Most detrimental to field crops are differential, red-legged, two-striped, and migratory grasshoppers. The migratory grasshopper (Melanoplus sanguinipes), and possibly many other species, can increase in population by up to 82 times within a single generation.

The differential grasshopper (Melanoplus differentialis) is often one of the first to move into gardens and is among the largest in its genus. M. sanguinipes is considered the most damaging to croplands due to its early hatching and ability to migrate long distances. The two-striped grasshopper (Melanoplus bivittatus) is a common garden pest, typically migrating from undisturbed areas such as roadsides and empty lots. It hatches in late spring, slightly later than many other species. The red-legged grasshopper (Melanoplus femurrubrum) is widely distributed and feeds on a variety of garden plants, preferring moist environments and hatching later in the season. Lastly, the clear-winged grasshopper (Camnula pellucida) has been a primary species in recent outbreaks, particularly in the West Slope and Steamboat Springs areas. It hatches early and feeds exclusively on grasses.

View U.S. Grasshopper Forecast Hazard Maps

Grasshopper management

Grasshoppers have been a significant economic concern in the western United States since the 1800s, when settlers began farming and ranching. In 1864, settlers in northeastern Colorado faced severe hardships when grasshoppers destroyed their crops. In 1873, many homesteaders in Fort Collins, Colorado, abandoned their land due to economic struggles and grasshopper infestations (Tresner 1981 within Capinera and Sechrist 1999). As Colorado's urban areas expand into foothills, prairies, and farmland, concerns about grasshoppers have grown. Grasshoppers typically begin causing damage to field crops and gardens by developing in weedy areas along roadsides, fence lines, irrigation ditches, and other non-crop locations. As their food sources are depleted or dry out, they migrate in search of more plants, often targeting irrigated crops or recently sprouted winter wheat.

Large-scale grasshopper management efforts have shifted focus from crop protection to rangeland protection. This change is largely because farmers have access to various insecticides that effectively control grasshopper populations and are financially motivated to do so. Additionally, other agricultural practices, such as insecticide use for other crop pests, tillage, ditch burning, and weed control, help keep grasshopper numbers low. In contrast, while ranchers also have access to effective insecticides, the lower productivity of rangeland compared to cropland makes costly control measures less economically viable.

The Colorado Department of Agriculture, with support from the USDA, conducts grasshopper adult surveys in late summer and early fall. These surveys help estimate grasshopper populations for the following summer. An adult count of eight or more per square yard is considered a possible threat. The potential for grasshopper damage varies widely, often depending on their host plant preferences. For instance, the Turnbull’s grasshopper (Aeoloplides turnbulli), one of Colorado’s most common grasshoppers, primarily feeds on Russian thistle and belvedere summer cypress. In areas where grass production is a priority, such species may be more beneficial than harmful.

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  Grasshoppers (Acrididae) of Colorado

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Outbreaks

Significant grasshopper outbreaks occurred in 1936–1938, 1957–1958, and 1980–1982, roughly every 22 years. Smaller outbreaks emerged midway between these major events. Notably, severe droughts in the western United States also follow a 22-year cycle, with less intense droughts occurring approximately every 11 years. Grasshopper populations seem to thrive under the favorable conditions created by high temperatures and low rainfall.

The last major outbreak was in the late 1970s and early 1980s.

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
Field guide to some of the common grasshoppers of the Front Range of Colorado		View	Agriculture, Behavior, Grasshoppers, Distribution, Species identification, Morphology, Photos, Biology, Overview	English	University of Colorado
Grasshopper control in gardens and small acreages	2013	View	Agriculture, Infestations, Grasshoppers, Biological control, Life cycle, Species identification	English	Colorado State University, W.S. Cranshaw, R. Hammon
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 (Acrididae) of Colorado	1982		Biology, Species identification, Ecology, Behavior, Physiology, Management	English	Colorado State University, John Capinera, TS Sechrist
Grasshoppers Are Descending on the West in Swarms	2021		Grasshoppers	English
Grasshoppers in field crops	2014	View	insecticide, Infestations, Chemical control, Spraying, Agriculture, Crop health, Grazing	English	Colorado State University, F.B. Peairs
Grasshoppers of Colorado presentation	N/A	View	Locusts, Life cycle, Grasshoppers, Control, Map, Outbreaks, Situation bulletin, Rainfall, Bait	English	University of Colorado
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
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
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 / Colorado