Big-headed grasshopper (Aulocara elliotti)
| Aulocara elliotti | |
|---|---|
 | |
| Other common names | |
| Bigheaded grasshopper, Largeheaded grasshopper | |
| Taxonomic classification | |
| Suborder: | Caelifera |
| Family: | Acrididae |
| Subfamily: | Gomphocerinae |
| Tribe: | Aulocarini |
| Genus: | Aulocara |
| Scientific name | |
| Aulocara elliotti (Thomas, 1870) | |
| Geography | |
| Native countries: | |
| Pest status | |
| Known pest | |
Bigheaded grasshopper (Aulocara elliotti) is a slant-faced species found primarily in dry grasslands and sagebrush habitats. Known for its large, blocky head and strong jumping legs, it is considered a serious rangeland pest in the United States due to its potential to compete with livestock for forage.
Taxonomy
For full nomenclature and taxonomic details of this taxon, see Orthoptera Species File No subspecies recorded for this taxon.
Identification
The big-headed grasshopper is a species of slant-faced grasshopper in the family Acrididae. Slant-faced grasshoppers are recognized by their angled facial profile and typically slender, streamlined bodies with forward-tipped, pointed heads. Most slant-faced grasshoppers in North America belong to the subfamily Gomphocerinae, commonly known as “stridulating slant-faced grasshoppers” or “tooth-legged grasshoppers,” named for the row of pegs on the inner hind legs of males used to produce sound by rubbing against the wing edges.[1] A smaller group with similar facial structure, the Acridinae, or “silent slant-faced grasshoppers”, lacks these pegs and does not produce sound. These silent forms are found in some parts of the United States but are absent from western Canadian grasslands.
The big-headed grasshopper belongs to Gomphocerinae. Members of this subfamily can be readily distinguished from other grasshopper groups: they lack the prosternal spine found in Melanoplinae and the large, colorful, lobed hind wings typical of Oedipodinae.[1] They also differ behaviorally and morphologically from Acridinae.
A few specialized anatomical terms are useful for identifying grasshoppers in this subfamily. Grasshoppers have four wings, with the leathery, protective front pair known as the tegmina. Just behind the head lies the pronotum, a saddle-shaped structure forming the upper part (notum) of the prothorax, the front segment of the thorax. Along the center of the pronotum runs the median carina, a raised ridge, which may be intersected by sulci. At the tip of the head, a central dent called the fastigium may be seen, flanked by lateral foveolae, shallow pits bordered by small ridges. These features, often visible with a hand lens, are key to distinguishing between closely related species within the subfamily.[1]
The big-headed grasshopper comes in shades of gray or brown, medium sized, with a noticeably large head. It has a faint white X on its back, and its hind legs have blue lower parts. The sides of its body often have a dark patch. Its front wings are brown or gray with dark spots, and the top part of the back legs has two light black bands. The wings are long enough to go past the end of the body.
It can be distinguished from the similar, but slightly smaller, white-whiskered grasshopper (Ageneotettix deorum) by its blue hind tibiae and triangular lateral foveolae (in A. deorum, these are rectangular).[1] The median carina is intersected by a single sulcus. This species often draws attention due to its frequent stridulation, courtship displays, and aggressive interactions—both with other A. elliotti males and with different grasshopper species.[1]
Identification details
The big-headed grasshopper is most commonly found in grayish-brown colors with dark markings and a distinctive light "X" on the pronotum.[2][3] Adults are small to medium-sized and have large heads with slightly slanted faces and spotted forewings. On the hind femur, there are two black bars on the upper part of the medial area, extending onto the upper marginal and inner medial area, with the knee appearing black. The hind tibia typically displays a medium blue hue.[4]
Nymphs have several distinct features. Their heads are characterized by triangular depressions on the sides, while the antennae are thin and flattened, and the face slopes moderately. Nymphs also have the light "X" marking on the pronotum. The hind leg has two dark bars mark the upper section, with several dark spots present on the lower part, while the hind tibia has a blue hue with three dark rings. [2]
Featured resources
All identification resources
| Title | Author(s) | Year | Geographic purview | URL |
|---|---|---|---|---|
| Common Grasshoppers of Montana Cropland and Rangeland | Montana State University | View URL | ||
| Insect answers | Daniel Suomi, Gary Thomasson and Dave Keim | 1990 | View URL | |
| Crickets and grasshoppers in Utah | Utah State University | 1931 | View URL | |
| Grasshoppers (Acrididae) of Colorado | Colorado State University,John Capinera,TS Sechrist | 1982 | ||
| A Manual of the Grasshoppers of New Mexico | New Mexico Cooperative Extension Service,D.B. Richman, D.C. Lightfoot, C.A. Sutherland and DJ. Ferguson | 1993 | View URL | |
| Grasshopper investigations on Montana rangelands | Montana State University,Norman L. Anderson and John C. Wright | 1952 | View URL | |
| Differentiation, ecology, and distribution of immature slant-faced grasshoppers (Acridinae) in Kansas | Kansas State University,Merlyn A. Brusven | 1967 | View URL | |
| Orthoptera of Northern Great Plains | North Dakota State University | 2007 | ||
| Hopper helper | Wendal Cushing | View URL | ||
| The grasshoppers of Nebraska | Animal and Plant Health Inspection Service,Mathew L. Brust, Wyatt Hoback and Robert J. Wright | 2009 | View URL | |
| Common Wyoming pest grasshoppers | University of Wyoming,Scott Schell and Alexandre Latchininsky,B.A. Shambaugh | View URL | ||
| Field guide to grasshoppers of economic importance in Nevada | University of Nevada | View URL | ||
| Pest grasshoppers in Oregon | Oregon Department of Agriculture,Thomas Valente and J. Buck Dunlap | 2024 | View URL | |
| Montana.gov Orthoptera Field Guides | View URL | |||
| Field Guide to Common Western Grasshoppers | United States Department of Agriculture,Robert E. Pfadt | 2002 | ||
| Grasshoppers of the Western United States | United States Department of Agriculture | View URL | ||
| ARS grasshopper species fact sheets | Agricultural Research Services and United States Department of Agriculture | 1994 | ||
| Pest Grasshoppers of the West | University of Wyoming | 2005 | View URL | |
| The Grasshoppers of the Western U.S. Lucid mobile app | APHIS PPQ Science & Technology Insect Management and Molecular Diagnostics Laboratory (Phoenix Station), United States Department of Agriculture and Center for Plant Health Science and Technology of the USDA | 2016 | ||
| Rangeland Grasshopper Management | University of Wyoming,Jeffrey Lockwood and Scott Schell | 1993 |
Distribution
The big-headed grasshopper is widely distributed throughout the western grasslands of North America, from the central Great Plains to the Pacific Ocean. It occurs in Southern Canadian provinces to north-central Mexico.[4] It can be found in British Columbia, Alberta, Manitoba, Minnesota, Iowa, Kansas, Oklahoma, Texas, Western Nebraska, Western North Dakota, Arizona, New Mexico, Washington, Oregon, Los Angeles, and California.[5] Substancial populations develop in the desert, mixedgrass, shortgrass, and bunchgrass prairies.[2]
Biology and ecology
The big-headed grasshopper typically hatches during mid-spring, spanning a period of three to four weeks.[3] It matures into adulthood within 36 to 42 days after hatching. They deposit their eggs in firm, smooth foam egg pods positioned just beneath the soil surface, typically near the bases of grasses in open areas. It lays eggs in pod within the upper 2 cm of soil in late summer or early fall and hatch the following spring.[5] Females appear to prefer bare areas on the south side of grass clump in crested wheatgrass fields.[6]
Adult bigheaded grasshoppers use their fully developed wings to fly for escape, dispersal, and migration. When disturbed, they fly silently, low to the ground (4–12 inches), and short distances (2–7 feet), moving with, against, or across the wind. While specific studies are limited, observations show they can travel long distances, up to seven miles in Arizona, and sudden population increases have been noted in previously low-density areas. Evidence of mass migration includes large numbers preserved in ice on Montana’s Grasshopper Glacier, likely from swarms originating in nearby mixed-grass prairies where outbreaks are common.[2]
Photos of this species
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Habitat and Ecology
Aulocara elliotti is a grass feeder and feeds heavily on blue grama, western wheatgrass, needleandthread, threadleaf sedge, and needleleaf sedge when these plants are available.[2]It consumes large quantities of cheatgrass in the spring and switches to other foods as the cheatgrass dries. Crested wheatgrass fields tend to have more bare ground between bunches which A. elliotti prefers for oviposition sites. [7] It does not feed on forbs by choice and avoids sagebrush. [8] [9] [3] [10] The bigheaded grasshopper feeds by climbing a grass blade, turning head-down, and chewing at various points, often cutting the leaf, which then falls and creates "wasted" grass for rangeland livestock. It may keep feeding on the remaining part. It also eats ground litter, cut grass, seeds, bran, and dead grasshoppers, while crawling on bare soil. [2]
Land-Use change
Pest status
The big-headed grasshopper is one of the top dozen species monitored by USDA Animal and Plant Health Inspection Service (APHIS) because of its impact on rangelands. This species can reach adult densities exceeding 50 individuals per square yard.[3] Populations tend to increase gradually over several years before experiencing sudden tripling or quadrupling in a single year. High populations of A. elliotti have been documented to persist for over five years.[3] This species often clips more grass than it consumes and can become the dominant grasshopper species during outbreaks. Over an entire season, even just one big-headed grasshopper per square meter can lower grassland productivity in a mixed-grass prairie by 22 kg of dry matter per hectare, equivalent to an 8% reduction.[11]
Particularly abundant in Canada in 2002.[1]
Management
Surveys by APHIS and its partners conducted in late summer or early autumn aim to locate big-headed grasshopper egg-laying sites. Another survey in late spring is scheduled to align with grasshopper hatching, helping to identify areas with high nymph concentrations for targeted treatment.[11]
The main strategy for managing big-headed grasshopper infestations on rangelands involves the use of insecticides applied via all-terrain vehicle (ATV)-mounted or aerial sprayers. Recommended insecticides include diflubenzuron, malathion, chlorantraniliprole, various pyrethroids, and carbaryl. Carbaryl can also be used in bait form, as the big-headed grasshopper readily consumes bait. Applications are made either through full-area coverage or using a method known as Reduced Agent and Area Treatments (RAATs). RAATs are an integrated pest management (IPM) technique where insecticide rates are lowered from standard levels, and treated swaths are alternated with untreated ones, reducing total coverage to 50% or less. This method combines direct chemical control (killing grasshoppers in treated areas and as they migrate from untreated zones) with conservation biological control, allowing natural enemies in untreated areas to help suppress the population. This IPM strategy can cut both insecticide use and treatment costs by more than half. Control efforts typically achieve around 80% effectiveness, which is adequate to suppress big-headed grasshopper populations. The insect growth regulator diflubenzuron has shown particular success in RAAT applications due to its long-lasting residual toxicity, which persists for about three weeks.[11][12][13] Pesticide control application rates for this species are available based on 2019 information in.[11]
Outbreaks
Outbreak media coverage
| Title | Author(s) | Year | Geographic purview | URL |
|---|---|---|---|---|
| Grasshopper and Mormon Cricket Outbreak Media | Oregon Department of Agriculture | 2022 |
Associated organizations
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Resources
| Title | Author(s) | Year | Geographic purview | URL |
|---|---|---|---|---|
| Common Grasshoppers of Montana Cropland and Rangeland | Montana State University | View URL | ||
| USDA grasshopper ecology and economics presentation | United States Department of Agriculture | N/A | View URL | |
| Insect answers | Daniel Suomi, Gary Thomasson and Dave Keim | 1990 | View URL | |
| Grasshopper and Mormon Cricket Outbreaks in Oregon Frequently Asked Questions | Oregon Department of Agriculture | 2022 | ||
| Crickets and grasshoppers in Utah | Utah State University | 1931 | View URL | |
| Grasshoppers (Acrididae) of Colorado | Colorado State University,John Capinera,TS Sechrist | 1982 | ||
| A Manual of the Grasshoppers of New Mexico | New Mexico Cooperative Extension Service,D.B. Richman, D.C. Lightfoot, C.A. Sutherland and DJ. Ferguson | 1993 | View URL | |
| Grasshopper investigations on Montana rangelands | Montana State University,Norman L. Anderson and John C. Wright | 1952 | View URL | |
| Differentiation, ecology, and distribution of immature slant-faced grasshoppers (Acridinae) in Kansas | Kansas State University,Merlyn A. Brusven | 1967 | View URL | |
| Orthoptera of Northern Great Plains | North Dakota State University | 2007 | ||
| Hopper helper | Wendal Cushing | View URL | ||
| The grasshoppers of Nebraska | Animal and Plant Health Inspection Service,Mathew L. Brust, Wyatt Hoback and Robert J. Wright | 2009 | View URL | |
| Common Wyoming pest grasshoppers | University of Wyoming,Scott Schell and Alexandre Latchininsky,B.A. Shambaugh | View URL | ||
| Field guide to grasshoppers of economic importance in Nevada | University of Nevada | View URL | ||
| Pest grasshoppers in Oregon | Oregon Department of Agriculture,Thomas Valente and J. Buck Dunlap | 2024 | View URL | |
| Montana.gov Orthoptera Field Guides | View URL | |||
| Field Guide to Common Western Grasshoppers | United States Department of Agriculture,Robert E. Pfadt | 2002 | ||
| Grasshoppers of the Western United States | United States Department of Agriculture | View URL | ||
| ARS grasshopper species fact sheets | Agricultural Research Services and United States Department of Agriculture | 1994 | ||
| Pest Grasshoppers of the West | University of Wyoming | 2005 | View URL | |
| The Grasshoppers of the Western U.S. Lucid mobile app | APHIS PPQ Science & Technology Insect Management and Molecular Diagnostics Laboratory (Phoenix Station), United States Department of Agriculture and Center for Plant Health Science and Technology of the USDA | 2016 | ||
| Rangeland Grasshopper Management | University of Wyoming,Jeffrey Lockwood and Scott Schell | 1993 |
Specimen contributors for this species
Bionomia links specimen records in GBIF to the people who collected and identified them. Each list shows the top 20 for this species. Read more…
Identified by
People who determined the taxonomic identity of specimens of this species.
- Tyler Grant — 12 specimens identified
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Johnson DL (n.d.) Slant-faced grasshoppers of the Canadian Prairies and Northern Great Plains. Environmental Health, Agriculture and Agri‑Food Canada Research Centre, Lethbridge, AB & University of Lethbridge, Lethbridge, AB, Canada. https://hopperwiki.org/images/5/5b/Slant-faced_grasshoppers_of_the_Canadian_Prairies_and_Northern_Great_Plains.pdf
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Pfadt RE (1994) Bigheaded Grasshopper Aulocara elliotti (Thomas). Wyoming Agricultural Experiment Station Bulletin 912. Species Fact Sheet. https://www.ars.usda.gov/ARSUserFiles/30320505/grasshopper/Extras/PDFs/Species%20Fact%20Sheets/Bighead.pdf
- ↑ 3.0 3.1 3.2 3.3 3.4 Schell SP, Latchininsky AV, Shambaugh BA (2005) Rangeland Grasshopper Management. 2nd Edition B-1161. Laramie, WY: University of Wyoming Cooperative Extension Service and Department of Renewable Resources. 76 p.
- ↑ 4.0 4.1 Capinera JL, Scott RD, Walker TJ (2005) Field guide to grasshoppers, katydids, and crickets of the United States. Cornell University Press, Ithaca, New York, 280 pp.
- ↑ 5.0 5.1 Pfadt RE (1949) Food-plants, distribution, and abundance of the big-headed grasshopper, Aulocara elliotti (Thos.). Journal of Kansas Entomological Society 22: 69-74.
- ↑ Fisher JR (1992) Location of Egg Pods of Aulocara elliotti (Orthoptera: Acrididae) in a Field of Crested Wheatgrass in Montana. Journal of the Kansas Entomological Society 65: 416–420.
- ↑ Kemp WP and Sanchez NE (1987) Differences in post-diapause thermal requirements for eggs of two rangeland grasshoppers. The Canadian Entomologist 119: 653-661.
- ↑ Mulkern GB, Toczek DR, Brusven MA (1964) Biology and ecology of North Dakota grasshoppers. II. Food habits and preferences of grasshoppers associated with the sandhill prairie. North Dakota Agricultural Experimental Station Research. Report 11.
- ↑ Pfadt RE, Lockwood JA, Foppe TM (1988) Diets of three common grasshoppers (Orthoptera: Acrididae) inhabiting desert grassland. The Canadian Entomologist. 120: 415-424.
- ↑ Fielding DJ and Brusven MA (1992) Food and Habitat Preferences of Melanoplus sanguinipes and Aulocara elliotti (Orthoptera: Acrididae) on Disturbed Rangeland in Southern Idaho. Journal of Economic Entomology, 85(3), 783–788. https://doi.org/10.1093/jee/85.3.783
- ↑ 11.0 11.1 11.2 11.3 Latchininsky A (2019) Bigheaded grasshopper Aulocara elliotti (Thomas, 1870) (Acrididae). In: Lecoq M, Zhang L (Eds) Encyclopedia of pest Orthoptera of the world. China Agricultural University Press, Beijing, China, pp. 21–24.
- ↑ Latchininsky AV, Schell SP (2007) Aerial RAATs brochure. ATV-RAATs brochure. UW CES Bulletin MP-95, Laramie, WY, USA.https://hopperwiki.org/index.php/UWYO_information_on_reduced_agent_and_area_treatments_(RAATs)
- ↑ Lockwood JA, Schell SP (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.