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Species Melanoplus spretus - Rocky Mountain Locust

Hopper ID - Melanoplus spretus - female Rocky Mountain Locust - Melanoplus spretus - male Rocky Mountain Locust - Melanoplus spretus - female
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Orthoptera (Grasshoppers, Crickets, Katydids)
Suborder Caelifera (Grasshoppers)
Family Acrididae (Short-horned Grasshoppers)
Subfamily Melanoplinae (Spur-throated Grasshoppers)
Tribe Melanoplini
Genus Melanoplus
Species spretus (Rocky Mountain Locust)
Other Common Names
Rocky Mountain grasshopper, hateful migratory locust, hateful grasshopper, Kansas grasshopper, criquet des montagnes rocheuses (French)
Synonyms and other taxonomic changes
Melanoplus spretus (Walsh) S.H. Scudder, 1878
Caloptenus spretus Walsh, 1866 (original combination). Described from Kansas
Explanation of Names
Species name spretus is Latin, meaning despised. Locust is from Latin, locus ustus, meaning "burnt place", alluding to denuded landscapes left by locusts (1).
Size
30-36 mm (head to tip of wings) (2)
body length 25 mm (male), 28 mm (female) (Scudder, 1898)
Identification
A long-winged and rather dull-patterned Melanoplus, notable for its fantastic swarms and damage to agriculture. It was one of the most abundant large insects in North America (and the world), but is now believed to be extinct. Historical illustrations can, perhaps, give some feeling for the living organism:
  

Apparently M. spretus was known mostly (or only?) as long-winged gregarious phase individuals, while these are only rarely seen in the similar M. sanguinipes, for instance. Definitive differentiation from other Melanoplus requires/required examination of genital structures of the male:
  
Range
Formerly resident in northern Rocky Mountain region of western North America, with episodic, and agriculturally devastating invasions southward and eastward into the Great Plains. Notable invasions occurred through the 1870's, but the species declined precipitously in the last decades of the 19th century. The last living specimens were seen in southern Canada in 1902 (collected by Norman Criddle near Wawanesa, Manitoba), and the species is now believed to be extinct (1). Historical maps show former breeding and irruptive ranges:
  
Life Cycle
Had a remarkable life cycle, with sedentary and migratory phases. One generation per year. Migratory swarms of immense size were documented in the upper Midwest in the 1870's. One 1875 swarm ("Albert's swarm") in Nebraska was documented with the aid of telegraphed reports and estimated to be 110 miles (180 km) wide by 1,800 miles (2,900 km) in length. This gives an area of 198,000 square miles (500,000 square km), larger than the state of Colorado. This swarm contained perhaps three trillion (3,000,000,000,000) individuals (1).
Remarks
Extinction (or not) and causes
There is still some debate as to whether the species is truly extinct. For one thing it is difficult to believe that it just vanished. Some cite control measures as being responsible, but this is unlikely to have exterminated all populations everywhere. A recent hypothesis is that agricultural activity and habitat alteration in the permanent habitation zone of the species disrupted oviposition sites in riparian habitats (Lockwood DeBrey, 1990; Lockwood, 2004). Certainly one cannot resist an analogy with the Passenger Pigeon, a swarming bird that seemed to breed successfully only in gigantic flocks, and whose population collapsed suddenly, perhaps due to persecution in its concentrated breeding areas. Other factors may have been important in the downfall of the locust, such as the demise of the American Bison and the American Beaver at roughly the same time. Suppression of prairie fires may also have had some effect on the species.
Relationship to other species of Melanoplus
The similarity to M. sanguinipes is very great, and it is likely that specimens would not be noticed and recognized outside of the context of their swarms, especially since the non-migratory phase may look more like the "average" M. sanguinipes. It has also been suggested that M. sanguinipes IS the non-migratory phase of M. spretus, and that the genitalia might be somewhat different in the two phases. However, no proof has been offered of this, and rearing experiments have indicated that migratory phase M. sanguinipes (which look similar to migratory M. spretus) have genitalia characteristic of M. sanguinipes and not like M. spretus. In addition, genetic/molecular studies of Melanoplus spretus specimens have supported the validity of the species. Indeed, the molecular studies suggest that the M. spretus may have been more closely related to Melanoplus bruneri than to M. sanguinipes (Chapcoa and Litzenbergerb, 2004). At any rate, absent proof that M. spretus still exists, it is generally presumed to be extinct.
Economic and ecological effects
There are a few other grasshopper species in North America that swarm on a local scale, and also some that have something similar to a migratory phase (produced under crowded conditions), but none of those has ever been recorded as producing massive migrations even remotely comparable to those of M. spretus. The extinction of this species left North America without a "locust" that swarms in devastating numbers, which has no doubt been a boon to agriculture. However its loss may have had detrimental effects on other species--the locust was an important food source for the (now extinct) Eskimo Curlew. The curlew declined in numbers as the locust died out, though the loss of the locust was likely one of several factors in the extinction of the curlew (Cornell University, All About Birds--Eskimo Curlew).
See Also
Melanoplus femurrubrum - Red-legged Grasshopper
Melanoplus sanguinipes - Migratory Grasshopper
Melanoplus bruneri - Bruner's Spur-throat Grasshopper
Print References
Chapcoa, W. and Litzenbergerb, W. (2004). A DNA investigation into the mysterious disappearance of the Rocky Mountain grasshopper, mega-pest of the 1800s. Molecular Phylogenetics and Evolution 30(3): 810-814 (link)
Helfer, How to Know the Grasshoppers, p. 218, fig. 346 (2)
Kellogg, American Insects, pp. 133, 136-139(3)
Lockwood, Jeffrey A. Locust: The Devastating Rise and Mysterious Disappearance of the Insect that Shaped the American Frontier. New York: Basic Books, 2004 (review here) (1)
Lockwood, J.A. and DeBrey, L.D. (1990). A solution for the sudden and unexplained extinction of the Rocky Mountain Grasshopper (Orthoptera: Acrididae), Environ. Entomol. 19, pp. 1194–1205 (abstract).
Scudder, Samuel Hubbard (1898). Revision of the orthopteran group Melanopli (Acridiidae), with special reference to North American forms. Proc. US National Museum 20: 1-421 (Biodiversity Heritage Libary)

Historical references:
Riley, C. V. The locust plague in the United States: being more particularly a treatise on the Rocky Mountain locust or so-called grasshopper, as it occurs east of the Rocky Mountains, with practical recommendations for its destruction. Chicago,Rand, McNally & Co.,1877 (BHL Link).
Riley, C.V., A.S. Packard, Jr., & C. Thomas. 1878. First annual report of the United States Entomological Commission. Government Printing Office, Washington, D.C. (includes illustrations of this, and similar, species) (BHL link)
C.V. Riley, A.S. Packard Jr. and C. Thomas, 1880, Second Annual Report of the United States Entomological Commission. Government Printing Office, Washington, D.C. (BHL Link)
Walsh. 1866. Practical Entomologist 2(1):1-2 (original description--BHL link)
Internet References
High Country News--details search for frozen Rocky Mountain Locusts in a western glacier
Colorado Historical Society: Bibliography on the Rocky Mountain Locust
Minnesota Historical Society: Grasshopper Plagues, 1873-1877
Works Cited
1.Locust: The Devastating Rise And Mysterious Disappearance Of The Insect That Shaped The American Frontier
Jeffrey A. Lockwood. 2004. Basic Books.
2.How to Know the Grasshoppers, Cockroaches, and Their Allies
Jacques R. Helfer. 1962. Wm. C. Brown Company.
3.American insects
Vernon L. Kellogg. 1905. H. Holt and Company.