Big-headed grasshopper (Aulocara elliotti)

From HopperWiki
Jump to navigation Jump to search

Big-headed grasshopper (Aulocara elliotti)
Big-headed grasshopper
Distribution
Washington, Oregon, California, Idaho, Nevada, Arizona, Utah, Montana, Wyoming, Colorado, New Mexico, North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas, Minnesota, Iowa, British Columbia, Alberta, Saskatchewan, Manitoba
Taxonomy
Family:Acrididae
Subfamily:Gomphocerinae
Genus:Aulocara
Additional resources
Full taxonomy at OSF

Bigheaded grasshopper (Aulocara elliotti) is a common and economically important species in western United States rangelands, often found in large numbers alongside the Migratory Grasshopper (Melanoplus sanguinipes). [1] It has been reported as a rangeland pest over a long period of time [2] and is among the most damaging species. [3]

Nomenclature

Aulocara elliotti (Thomas, 1870). For full nomenclature, see this taxon's page on Orthoptera Species File


Identification

The big-headed grasshopper is most commonly found in grayish-brown colors with dark markings and a distinctive light "X" on the pronotum.[4] [5] Adults are medium-sized and have relatively 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.

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.[4] Nymphs also have the light "X" marking on the pronotum. Moving to the hind leg, 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.

Identification [5] [4]
Stage Color Wings Body length
Nymph gray and tan with dark markings 5 - 6 mm (First instar)
Female adult grayish-brown colors with dark markings spotted forewings 20 - 25 mm
Male adult grayish-brown colors with dark markings spotted forewings 17 - 20 mm

Identification resources

Name Year published Resource link Descriptive keyword Language Geographic purview Author Year published
Field Guide to Common Western Grasshoppers 2002 View URL Species identification English United States of America United States Department of Agriculture 2002
Grasshoppers of the Western United States View URL Management, Species identification English United States of America United States Department of Agriculture
Montana.gov grasshopper field guides View URL Species identification, Management, Biology English United States of America
Orthoptera Species File View URL Species identification, Biology English Africa, Americas, Asia, Europe, Oceania Orthoptera Species File Online
Pest Grasshoppers of the West 2005 View URL Management, Species identification English United States of America 2005
Rangeland Grasshopper Management View URL Management, Species identification English United States of America University of Wyoming
The Grasshoppers of the Western U.S. Lucid mobile app 2016 View URL Management, Species identification English United States of America 2016
USDA ARS grasshopper species fact sheets View URL Management, Species identification English United States of America Agricultural Research Services, United States Department of Agriculture



Distribution

The big-headed grasshopper is predominantly found throughout the western grasslands of North America, from Southern Canada to central Mexico. 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.[6] Substancial populations develop in the desert, mixedgrass, shortgrass, and bunchgrass prairies.[4]

Biology

The big-headed grasshopper typically hatches during mid-spring, spanning a period of three to four weeks.[5] It generally 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.[6] Females appear to prefer bare areas on the south side of grass clump in crested wheatgrass fields.[1]

Life cycle parameters
Phase Developmental time
Eggs
Hopper
Adult
Laying-fledging
Adult maturation
Total


Habitat and Ecology

Aulocara elliotti is a grass feeder and prefers crested and western wheatgrass and blue grama. This species does not feed on forbs by choice and avoids sagebrush. [7] [8] [5] [9] 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. [10]

This species can reach adult densities exceeding 50 individuals per square yard.[5] Populations tend to increase gradually over several years before experiencing sudden tripling or quadrupling in a single year. Frequently dominating outbreaks, high populations of A. elliotti have been documented to persist for over five years.[5]

Land-Use Change

Pest status

Outbreak media coverage

Querying the database found no results.


Associated organizations

Querying the database found no results.


Resources

Name Year published Resource link Descriptive keyword Language Geographic purview Author Year published
Sustainable use and conservation of microbial and invertebrate biological control agents and microbial biostimulants 2023 View URL Management, Biological control, Biopesticide English Africa, Americas, Asia, Europe, Oceania Centre for Agriculture and Bioscience International 2023



References

  1. 1.0 1.1 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.
  2. Cooley RA (1904) Grasshoppers. Montana Agricultural Experimental Station Bulletin. 51:232-242.
  3. Mulkern GB, Pruess KP, Knutson H, Hagen AF, Campbell JB, Lambley JD (1969) Food habits and preferences of grassland grasshoppers of the north central Great Plains. North Dakota Agricultural Experimental Station Bulletin No. 481. 32 p
  4. 4.0 4.1 4.2 4.3 Pfadt RE (2002) Field Guide to Common Western Grasshoppers, 3rd edition. Laramie, WY: Wyoming Agricultural Experiment Station, Bulletin 912, modified by S. Schell and S. Schell for electronic publication. Accessed 9 May 2024. http://www.uwyo.edu/entomology/grasshoppers/field-guide/index.html#fieldguidetoc
  5. 5.0 5.1 5.2 5.3 5.4 5.5 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.
  6. 6.0 6.1 Pfadt RE (1949) Food-plants, distribution, and abundance of the big-headed grasshopper, Aulocara elliotti (Thos.). Journal of Kansas Entomological Society 22: 69-74.
  7. 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.
  8. Pfadt RE, Lockwood JA, Foppe TM (1988) Diets of three common grasshoppers (Orthoptera: Acrididae) inhabiting desert grassland. The Canadian Entomologist. 120: 415-424.
  9. 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
  10. Kemp WP and Sanchez NE (1987) Differences in post-diapause thermal requirements for eggs of two rangeland grasshoppers. The Canadian Entomologist 119: 653-661.